-Lua 5.3 Reference Manual
+Lua 5.4 Reference Manual
-Lua 5.3 Reference Manual
+Lua 5.4 Reference Manual
The reference manual is the official definition of the Lua language.
For a complete introduction to Lua programming, see the book
Programming in Lua.
-Copyright © 2015–2020 Lua.org, PUC-Rio. +Copyright © 2020 Lua.org, PUC-Rio. Freely available under the terms of the Lua license.
-Lua 5.3 Reference Manual
+Lua 5.4 Reference Manual
by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, Waldemar Celes
-Copyright © 2015–2020 Lua.org, PUC-Rio. +Copyright © 2020 Lua.org, PUC-Rio. Freely available under the terms of the Lua license.
- +
Lua is a powerful, efficient, lightweight, embeddable scripting language. It supports procedural programming, object-oriented programming, functional programming, data-driven programming, and data description.
Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting bytecode with a register-based virtual machine, and has automatic memory management with -incremental garbage collection, +a generational garbage collection, making it ideal for configuration, scripting, and rapid prototyping.
Lua is implemented as a library, written in clean C,
the common subset of Standard C and C++.
The Lua distribution includes a host program called lua,
which uses the Lua library to offer a complete,
standalone Lua interpreter,
for interactive or batch use.
Lua is intended to be used both as a powerful, lightweight,
embeddable scripting language for any program that needs one,
and as a powerful but lightweight and efficient stand-alone language.
As an extension language, Lua has no notion of a "main" program:
it works embedded in a host client,
called the embedding program or simply the host.
(Frequently, this host is the stand-alone lua program.)
The host program can invoke functions to execute a piece of Lua code,
can write and read Lua variables,
and can register C functions to be called by Lua code.
Through the use of C functions, Lua can be augmented to cope with
a wide range of different domains,
thus creating customized programming languages sharing a syntactical framework.
Lua is free software,
and is provided as usual with no guarantees,
as stated in its license.
The implementation described in this manual is available
at Lua's official web site, www.lua.org.
Like any other reference manual, this document is dry in places. For a discussion of the decisions behind the design of Lua, see the technical papers available at Lua's web site. For a detailed introduction to programming in Lua, see Roberto's book, Programming in Lua.
This section describes the basic concepts of the language. + +
-Lua is a dynamically typed language. +Lua is a dynamically typed language. This means that variables do not have types; only values do. There are no type definitions in the language. All values carry their own type.
-All values in Lua are first-class values. +All values in Lua are first-class values. This means that all values can be stored in variables, passed as arguments to other functions, and returned as results.
There are eight basic types in Lua:
nil, boolean, number,
string, function, userdata,
thread, and table.
The type nil has one single value, nil,
whose main property is to be different from any other value;
-it usually represents the absence of a useful value.
+it often represents the absence of a useful value.
The type boolean has two values, false and true.
Both nil and false make a condition false;
-any other value makes it true.
-The type number represents both
-integer numbers and real (floating-point) numbers.
-The type string represents immutable sequences of bytes.
-
-Lua is 8-bit clean:
-strings can contain any 8-bit value,
-including embedded zeros ('\0').
-Lua is also encoding-agnostic;
-it makes no assumptions about the contents of a string.
+they are collectively called false values.
+Any other value makes a condition true.
-The type number uses two internal representations,
-or two subtypes,
-one called integer and the other called float.
-Lua has explicit rules about when each representation is used,
-but it also converts between them automatically as needed (see §3.4.3).
-Therefore,
-the programmer may choose to mostly ignore the difference
-between integers and floats
-or to assume complete control over the representation of each number.
+The type number represents both
+integer numbers and real (floating-point) numbers,
+using two subtypes: integer and float.
Standard Lua uses 64-bit integers and double-precision (64-bit) floats,
but you can also compile Lua so that it
uses 32-bit integers and/or single-precision (32-bit) floats.
The option with 32 bits for both integers and floats
is particularly attractive
for small machines and embedded systems.
(See macro LUA_32BITS in file luaconf.h.)
+
+Unless stated otherwise, +any overflow when manipulating integer values wrap around, +according to the usual rules of two-complement arithmetic. +(In other words, +the actual result is the unique representable integer +that is equal modulo 2n to the mathematical result, +where n is the number of bits of the integer type.) + + +
+Lua has explicit rules about when each subtype is used, +but it also converts between them automatically as needed (see §3.4.3). +Therefore, +the programmer may choose to mostly ignore the difference +between integers and floats +or to assume complete control over the representation of each number. + + +
+The type string represents immutable sequences of bytes.
+
+Lua is 8-bit clean:
+strings can contain any 8-bit value,
+including embedded zeros ('\0').
+Lua is also encoding-agnostic;
+it makes no assumptions about the contents of a string.
+The length of any string in Lua must fit in a Lua integer.
+
+
Lua can call (and manipulate) functions written in Lua and functions written in C (see §3.4.10). Both are represented by the type function.
The type userdata is provided to allow arbitrary C data to be stored in Lua variables. A userdata value represents a block of raw memory. There are two kinds of userdata: full userdata, which is an object with a block of memory managed by Lua, and light userdata, which is simply a C pointer value. Userdata has no predefined operations in Lua, except assignment and identity test. By using metatables, the programmer can define operations for full userdata values (see §2.4). Userdata values cannot be created or modified in Lua, only through the C API. -This guarantees the integrity of data owned by the host program. +This guarantees the integrity of data owned by +the host program and C libraries.
The type thread represents independent threads of execution and it is used to implement coroutines (see §2.6). Lua threads are not related to operating-system threads. Lua supports coroutines on all systems, even those that do not support threads natively.
The type table implements associative arrays,
that is, arrays that can have as indices not only numbers,
but any Lua value except nil and NaN.
-(Not a Number is a special value used to represent
-undefined or unrepresentable numerical results, such as 0/0.)
+(Not a Number is a special floating-point value
+used by the IEEE 754 standard to represent
+undefined numerical results, such as 0/0.)
Tables can be heterogeneous;
that is, they can contain values of all types (except nil).
-Any key with value nil is not considered part of the table.
+Any key associated to the value nil is not considered part of the table.
Conversely, any key that is not part of a table has
an associated value nil.
Tables are the sole data-structuring mechanism in Lua;
they can be used to represent ordinary arrays, lists,
symbol tables, sets, records, graphs, trees, etc.
To represent records, Lua uses the field name as an index.
The language supports this representation by
providing a.name as syntactic sugar for a["name"].
There are several convenient ways to create tables in Lua
(see §3.4.9).
Like indices, the values of table fields can be of any type. In particular, because functions are first-class values, table fields can contain functions. Thus tables can also carry methods (see §3.4.11).
The indexing of tables follows
the definition of raw equality in the language.
The expressions a[i] and a[j]
denote the same table element
if and only if i and j are raw equal
(that is, equal without metamethods).
In particular, floats with integral values
are equal to their respective integers
(e.g., 1.0 == 1).
To avoid ambiguities,
-any float with integral value used as a key
-is converted to its respective integer.
+any float used as a key that is equal to an integer
+is converted to that integer.
For instance, if you write a[2.0] = true,
-the actual key inserted into the table will be the
-integer 2.
-(On the other hand,
-2 and "2" are different Lua values and therefore
-denote different table entries.)
+the actual key inserted into the table will be the integer 2.
Tables, functions, threads, and (full) userdata values are objects: variables do not actually contain these values, only references to them. Assignment, parameter passing, and function returns always manipulate references to such values; these operations do not imply any kind of copy.
The library function type returns a string describing the type
-of a given value (see §6.1).
+of a given value (see type).
-As will be discussed in §3.2 and §3.3.3,
+As we will discuss further in §3.2 and §3.3.3,
any reference to a free name
(that is, a name not bound to any declaration) var
is syntactically translated to _ENV.var.
Moreover, every chunk is compiled in the scope of
an external local variable named _ENV (see §3.3.2),
so _ENV itself is never a free name in a chunk.
Despite the existence of this external _ENV variable and
the translation of free names,
_ENV is a completely regular name.
In particular,
you can define new variables and parameters with that name.
Each reference to a free name uses the _ENV that is
visible at that point in the program,
following the usual visibility rules of Lua (see §3.5).
Any table used as the value of _ENV is called an environment.
Lua keeps a distinguished environment called the global environment.
-This value is kept at a special index in the C registry (see §4.5).
+This value is kept at a special index in the C registry (see §4.3).
In Lua, the global variable _G is initialized with this same value.
-(_G is never used internally.)
+(_G is never used internally,
+so changing its value will affect only your own code.)
When Lua loads a chunk,
-the default value for its _ENV upvalue
+the default value for its _ENV variable
is the global environment (see load).
Therefore, by default,
free names in Lua code refer to entries in the global environment
-(and, therefore, they are also called global variables).
+and, therefore, they are also called global variables.
Moreover, all standard libraries are loaded in the global environment
and some functions there operate on that environment.
You can use load (or loadfile)
to load a chunk with a different environment.
(In C, you have to load the chunk and then change the value
-of its first upvalue.)
+of its first upvalue; see lua_setupvalue.)
+Several operations in Lua can raise an error. +An error interrupts the normal flow of the program, +which can continue by catching the error. + + +
+Lua code can explicitly raise an error by calling the
+error function.
+(This function never returns.)
+
+
+
+To catch errors in Lua,
+you can do a protected call,
+using pcall (or xpcall).
+The function pcall calls a given function in protected mode.
+Any error while running the function stops its execution,
+and control returns immediately to pcall,
+which returns a status code.
+
+
Because Lua is an embedded extension language,
-all Lua actions start from C code in the host program
-calling a function from the Lua library.
+Lua code starts running by a call
+from C code in the host program.
(When you use Lua standalone,
the lua application is the host program.)
-Whenever an error occurs during
+Usually, this call is protected;
+so, when an otherwise unprotected error occurs during
the compilation or execution of a Lua chunk,
control returns to the host,
-which can take appropriate measures
-(such as printing an error message).
-
-
-
-Lua code can explicitly generate an error by calling the
-error function.
-If you need to catch errors in Lua,
-you can use pcall or xpcall
-to call a given function in protected mode.
+which can take appropriate measures,
+such as printing an error message.
Whenever there is an error, -an error object (also called an error message) +an error object is propagated with information about the error. Lua itself only generates errors whose error object is a string, but programs may generate errors with any value as the error object. It is up to the Lua program or its host to handle such error objects. +For historical reasons, +an error object is often called an error message, +even though it does not have to be a string.
-When you use xpcall or lua_pcall,
+When you use xpcall (or lua_pcall, in C)
you may give a message handler
to be called in case of errors.
This function is called with the original error object
and returns a new error object.
It is called before the error unwinds the stack,
so that it can gather more information about the error,
for instance by inspecting the stack and creating a stack traceback.
This message handler is still protected by the protected call;
so, an error inside the message handler
will call the message handler again.
If this loop goes on for too long,
Lua breaks it and returns an appropriate message.
-(The message handler is called only for regular runtime errors.
+The message handler is called only for regular runtime errors.
It is not called for memory-allocation errors
-nor for errors while running finalizers.)
+nor for errors while running finalizers or other message handlers.
+
+
+
+Lua also offers a system of warnings (see warn).
+Unlike errors, warnings do not interfere
+in any way with program execution.
+They typically only generate a message to the user,
+although this behavior can be adapted from C (see lua_setwarnf).
Every value in Lua can have a metatable.
This metatable is an ordinary Lua table
that defines the behavior of the original value
-under certain special operations.
+under certain events.
You can change several aspects of the behavior
-of operations over a value by setting specific fields in its metatable.
+of a value by setting specific fields in its metatable.
For instance, when a non-numeric value is the operand of an addition,
Lua checks for a function in the field "__add" of the value's metatable.
If it finds one,
Lua calls this function to perform the addition.
The key for each event in a metatable is a string
with the event name prefixed by two underscores;
-the corresponding values are called metamethods.
-In the previous example, the key is "__add"
+the corresponding value is called a metavalue.
+For most events, the metavalue must be a function,
+which is then called a metamethod.
+In the previous example, the key is the string "__add"
and the metamethod is the function that performs the addition.
Unless stated otherwise,
-metamethods should be function values.
+a metamethod may in fact be any callable value,
+which is either a function or a value with a __call metamethod.
You can query the metatable of any value
using the getmetatable function.
Lua queries metamethods in metatables using a raw access (see rawget).
-So, to retrieve the metamethod for event ev in object o,
-Lua does the equivalent to the following code:
-
- rawget(getmetatable(o) or {}, "__ev")
-
You can replace the metatable of tables
using the setmetatable function.
-You cannot change the metatable of other types from Lua code
-(except by using the debug library (§6.10));
-you should use the C API for that.
+You cannot change the metatable of other types from Lua code,
+except by using the debug library (§6.10).
-Tables and full userdata have individual metatables -(although multiple tables and userdata can share their metatables). +Tables and full userdata have individual metatables, +although multiple tables and userdata can share their metatables. Values of all other types share one single metatable per type; that is, there is one single metatable for all numbers, one for all strings, etc. By default, a value has no metatable, but the string library sets a metatable for the string type (see §6.4).
-A metatable controls how an object behaves in -arithmetic operations, bitwise operations, -order comparisons, concatenation, length operation, calls, and indexing. -A metatable also can define a function to be called -when a userdata or a table is garbage collected (§2.5). - - -
-For the unary operators (negation, length, and bitwise NOT), -the metamethod is computed and called with a dummy second operand, -equal to the first one. -This extra operand is only to simplify Lua's internals -(by making these operators behave like a binary operation) -and may be removed in future versions. -(For most uses this extra operand is irrelevant.) - - -
-A detailed list of events controlled by metatables is given next. -Each operation is identified by its corresponding key. +A detailed list of operations controlled by metatables is given next. +Each event is identified by its corresponding key. +By convention, all metatable keys used by Lua are composed by +two underscores followed by lowercase Latin letters.
__add:
the addition (+) operation.
-If any operand for an addition is not a number
-(nor a string coercible to a number),
+If any operand for an addition is not a number,
Lua will try to call a metamethod.
-First, Lua will check the first operand (even if it is valid).
-If that operand does not define a metamethod for __add,
+It starts by checking the first operand (even if it is a number);
+if that operand does not define a metamethod for __add,
then Lua will check the second operand.
If Lua can find a metamethod,
it calls the metamethod with the two operands as arguments,
and the result of the call
(adjusted to one value)
is the result of the operation.
-Otherwise,
-it raises an error.
+Otherwise, if no metamethod is found,
+Lua raises an error.
__sub:
the subtraction (-) operation.
Behavior similar to the addition operation.
__mul:
the multiplication (*) operation.
Behavior similar to the addition operation.
__div:
the division (/) operation.
Behavior similar to the addition operation.
__mod:
the modulo (%) operation.
Behavior similar to the addition operation.
__pow:
the exponentiation (^) operation.
Behavior similar to the addition operation.
__unm:
the negation (unary -) operation.
Behavior similar to the addition operation.
__idiv:
the floor division (//) operation.
Behavior similar to the addition operation.
__band:
the bitwise AND (&) operation.
Behavior similar to the addition operation,
except that Lua will try a metamethod
if any operand is neither an integer
-nor a value coercible to an integer (see §3.4.3).
+nor a float coercible to an integer (see §3.4.3).
__bor:
the bitwise OR (|) operation.
Behavior similar to the bitwise AND operation.
__bxor:
the bitwise exclusive OR (binary ~) operation.
Behavior similar to the bitwise AND operation.
__bnot:
the bitwise NOT (unary ~) operation.
Behavior similar to the bitwise AND operation.
__shl:
the bitwise left shift (<<) operation.
Behavior similar to the bitwise AND operation.
__shr:
the bitwise right shift (>>) operation.
Behavior similar to the bitwise AND operation.
__concat:
the concatenation (..) operation.
Behavior similar to the addition operation,
except that Lua will try a metamethod
if any operand is neither a string nor a number
(which is always coercible to a string).
__len:
the length (#) operation.
If the object is not a string,
Lua will try its metamethod.
If there is a metamethod,
Lua calls it with the object as argument,
and the result of the call
(always adjusted to one value)
is the result of the operation.
If there is no metamethod but the object is a table,
then Lua uses the table length operation (see §3.4.7).
Otherwise, Lua raises an error.
__eq:
the equal (==) operation.
Behavior similar to the addition operation,
except that Lua will try a metamethod only when the values
being compared are either both tables or both full userdata
and they are not primitively equal.
The result of the call is always converted to a boolean.
__lt:
the less than (<) operation.
Behavior similar to the addition operation,
except that Lua will try a metamethod only when the values
being compared are neither both numbers nor both strings.
-The result of the call is always converted to a boolean.
+Moreover, the result of the call is always converted to a boolean.
__le:
the less equal (<=) operation.
-Unlike other operations,
-the less-equal operation can use two different events.
-First, Lua looks for the __le metamethod in both operands,
-like in the less than operation.
-If it cannot find such a metamethod,
-then it will try the __lt metamethod,
-assuming that a <= b is equivalent to not (b < a).
-As with the other comparison operators,
-the result is always a boolean.
-(This use of the __lt event can be removed in future versions;
-it is also slower than a real __le metamethod.)
+Behavior similar to the less than operation.
__index:
The indexing access operation table[key].
This event happens when table is not a table or
when key is not present in table.
-The metamethod is looked up in table.
+The metavalue is looked up in the metatable of table.
-Despite the name,
-the metamethod for this event can be either a function or a table.
+The metavalue for this event can be either a function, a table,
+or any value with an __index metavalue.
If it is a function,
it is called with table and key as arguments,
and the result of the call
(adjusted to one value)
is the result of the operation.
-If it is a table,
-the final result is the result of indexing this table with key.
-(This indexing is regular, not raw,
-and therefore can trigger another metamethod.)
+Otherwise,
+the final result is the result of indexing this metavalue with key.
+This indexing is regular, not raw,
+and therefore can trigger another __index metavalue.
__newindex:
The indexing assignment table[key] = value.
Like the index event,
this event happens when table is not a table or
when key is not present in table.
-The metamethod is looked up in table.
+The metavalue is looked up in the metatable of table.
Like with indexing,
-the metamethod for this event can be either a function or a table.
+the metavalue for this event can be either a function, a table,
+or any value with an __newindex metavalue.
If it is a function,
it is called with table, key, and value as arguments.
-If it is a table,
-Lua does an indexing assignment to this table with the same key and value.
-(This assignment is regular, not raw,
-and therefore can trigger another metamethod.)
+Otherwise,
+Lua repeats the indexing assignment over this metavalue
+with the same key and value.
+This assignment is regular, not raw,
+and therefore can trigger another __newindex metavalue.
-Whenever there is a __newindex metamethod,
+Whenever a __newindex metavalue is invoked,
Lua does not perform the primitive assignment.
-(If necessary,
+If needed,
the metamethod itself can call rawset
-to do the assignment.)
+to do the assignment.
__call:
The call operation func(args).
This event happens when Lua tries to call a non-function value
(that is, func is not a function).
The metamethod is looked up in func.
If present,
the metamethod is called with func as its first argument,
followed by the arguments of the original call (args).
All results of the call
-are the result of the operation.
-(This is the only metamethod that allows multiple results.)
+are the results of the operation.
+This is the only metamethod that allows multiple results.
-It is a good practice to add all needed metamethods to a table
-before setting it as a metatable of some object.
-In particular, the __gc metamethod works only when this order
-is followed (see §2.5.1).
+In addition to the previous list,
+the interpreter also respects the following keys in metatables:
+__gc (see §2.5.3),
+__close (see §3.3.8),
+__mode (see §2.5.4),
+and __name.
+(The entry __name,
+when it contains a string,
+may be used by tostring and in error messages.)
+
+
+
+For the unary operators (negation, length, and bitwise NOT), +the metamethod is computed and called with a dummy second operand, +equal to the first one. +This extra operand is only to simplify Lua's internals +(by making these operators behave like a binary operation) +and may be removed in future versions. +For most uses this extra operand is irrelevant.
Because metatables are regular tables,
they can contain arbitrary fields,
not only the event names defined above.
Some functions in the standard library
(e.g., tostring)
use other fields in metatables for their own purposes.
+
+It is a good practice to add all needed metamethods to a table
+before setting it as a metatable of some object.
+In particular, the __gc metamethod works only when this order
+is followed (see §2.5.3).
+It is also a good practice to set the metatable of an object
+right after its creation.
+
+
Lua performs automatic memory management. This means that you do not have to worry about allocating memory for new objects or freeing it when the objects are no longer needed. Lua manages memory automatically by running -a garbage collector to collect all dead objects -(that is, objects that are no longer accessible from Lua). +a garbage collector to collect all dead objects. All memory used by Lua is subject to automatic management: strings, tables, userdata, functions, threads, internal structures, etc.
-Lua implements an incremental mark-and-sweep collector. -It uses two numbers to control its garbage-collection cycles: -the garbage-collector pause and -the garbage-collector step multiplier. -Both use percentage points as units -(e.g., a value of 100 means an internal value of 1). +An object is considered dead +as soon as the collector can be sure the object +will not be accessed again in the normal execution of the program. +("Normal execution" here excludes finalizers, +which can resurrect dead objects (see §2.5.3), +and excludes also operations using the debug library.) +Note that the time when the collector can be sure that an object +is dead may not coincide with the programmer's expectations. +The only guarantees are that Lua will not collect an object +that may still be accessed in the normal execution of the program, +and it will eventually collect an object +that is inaccessible from Lua. +(Here, +inaccessible from Lua means that neither a variable nor +another live object refer to the object.) +Because Lua has no knowledge about C code, +it never collects objects accessible through the registry (see §4.3), +which includes the global environment (see §2.2). + + +
+The garbage collector (GC) in Lua can work in two modes: +incremental and generational. + + +
+The default GC mode with the default parameters +are adequate for most uses. +However, programs that waste a large proportion of their time +allocating and freeing memory can benefit from other settings. +Keep in mind that the GC behavior is non-portable +both across platforms and across different Lua releases; +therefore, optimal settings are also non-portable. + + +
+You can change the GC mode and parameters by calling
+lua_gc in C
+or collectgarbage in Lua.
+You can also use these functions to control
+the collector directly (e.g., to stop and restart it).
+
+
+
+
+
+
+In incremental mode, +each GC cycle performs a mark-and-sweep collection in small steps +interleaved with the program's execution. +In this mode, +the collector uses three numbers to control its garbage-collection cycles: +the garbage-collector pause, +the garbage-collector step multiplier, +and the garbage-collector step size.
The garbage-collector pause controls how long the collector waits before starting a new cycle. +The collector starts a new cycle when the use of memory +hits n% of the use after the previous collection. Larger values make the collector less aggressive. -Values smaller than 100 mean the collector will not wait to +Values equal to or less than 100 mean the collector will not wait to start a new cycle. A value of 200 means that the collector waits for the total memory in use to double before starting a new cycle. +The default value is 200; the maximum value is 1000.
The garbage-collector step multiplier -controls the relative speed of the collector relative to -memory allocation. +controls the speed of the collector relative to +memory allocation, +that is, +how many elements it marks or sweeps for each +kilobyte of memory allocated. Larger values make the collector more aggressive but also increase the size of each incremental step. -You should not use values smaller than 100, +You should not use values less than 100, because they make the collector too slow and can result in the collector never finishing a cycle. -The default is 200, -which means that the collector runs at "twice" -the speed of memory allocation. +The default value is 100; the maximum value is 1000.
-If you set the step multiplier to a very large number -(larger than 10% of the maximum number of -bytes that the program may use), -the collector behaves like a stop-the-world collector. -If you then set the pause to 200, -the collector behaves as in old Lua versions, -doing a complete collection every time Lua doubles its -memory usage. +The garbage-collector step size controls the +size of each incremental step, +specifically how many bytes the interpreter allocates +before performing a step. +This parameter is logarithmic: +A value of n means the interpreter will allocate 2n +bytes between steps and perform equivalent work during the step. +A large value (e.g., 60) makes the collector a stop-the-world +(non-incremental) collector. +The default value is 13, +which means steps of approximately 8 Kbytes. + + + +
-You can change these numbers by calling lua_gc in C
-or collectgarbage in Lua.
-You can also use these functions to control
-the collector directly (e.g., stop and restart it).
+In generational mode,
+the collector does frequent minor collections,
+which traverses only objects recently created.
+If after a minor collection the use of memory is still above a limit,
+the collector does a stop-the-world major collection,
+which traverses all objects.
+The generational mode uses two parameters:
+the minor multiplier and the the major multiplier.
+
+The minor multiplier controls the frequency of minor collections. +For a minor multiplier x, +a new minor collection will be done when memory +grows x% larger than the memory in use after the previous major +collection. +For instance, for a multiplier of 20, +the collector will do a minor collection when the use of memory +gets 20% larger than the use after the previous major collection. +The default value is 20; the maximum value is 200. -
+The major multiplier controls the frequency of major collections. +For a major multiplier x, +a new major collection will be done when memory +grows x% larger than the memory in use after the previous major +collection. +For instance, for a multiplier of 100, +the collector will do a major collection when the use of memory +gets larger than twice the use after the previous collection. +The default value is 100; the maximum value is 1000. + + + + + +
You can set garbage-collector metamethods for tables and, using the C API, for full userdata (see §2.4). -These metamethods are also called finalizers. +These metamethods, called finalizers, +are called when the garbage collector detects that the +corresponding table or userdata is dead. Finalizers allow you to coordinate Lua's garbage collection -with external resource management -(such as closing files, network or database connections, -or freeing your own memory). +with external resource management such as closing files, +network or database connections, +or freeing your own memory.
For an object (table or userdata) to be finalized when collected,
you must mark it for finalization.
You mark an object for finalization when you set its metatable
and the metatable has a field indexed by the string "__gc".
Note that if you set a metatable without a __gc field
and later create that field in the metatable,
the object will not be marked for finalization.
-When a marked object becomes garbage,
+When a marked object becomes dead,
it is not collected immediately by the garbage collector.
Instead, Lua puts it in a list.
After the collection,
Lua goes through that list.
For each object in the list,
it checks the object's __gc metamethod:
-If it is a function,
-Lua calls it with the object as its single argument;
-if the metamethod is not a function,
-Lua simply ignores it.
+If it is present,
+Lua calls it with the object as its single argument.
At the end of each garbage-collection cycle, -the finalizers for objects are called in +the finalizers are called in the reverse order that the objects were marked for finalization, among those collected in that cycle; that is, the first finalizer to be called is the one associated with the object marked last in the program. The execution of each finalizer may occur at any point during the execution of the regular code.
Because the object being collected must still be used by the finalizer, that object (and other objects accessible only through it) must be resurrected by Lua. Usually, this resurrection is transient, and the object memory is freed in the next garbage-collection cycle. However, if the finalizer stores the object in some global place (e.g., a global variable), then the resurrection is permanent. Moreover, if the finalizer marks a finalizing object for finalization again, its finalizer will be called again in the next cycle where the -object is unreachable. +object is dead. In any case, the object memory is freed only in a GC cycle where -the object is unreachable and not marked for finalization. +the object is dead and not marked for finalization.
When you close a state (see lua_close),
Lua calls the finalizers of all objects marked for finalization,
following the reverse order that they were marked.
If any finalizer marks objects for collection during that phase,
these marks have no effect.
+
+Finalizers cannot yield. +Except for that, they can do anything, +such as raise errors, create new objects, +or even run the garbage collector. +However, because they can run in unpredictable times, +it is good practice to restrict each finalizer +to the minimum necessary to properly release +its associated resource. + + +
+Any error while running a finalizer generates a warning; +the error is not propagated. + -
A weak table is a table whose elements are weak references. A weak reference is ignored by the garbage collector. In other words, if the only references to an object are weak references, then the garbage collector will collect that object.
A weak table can have weak keys, weak values, or both.
A table with weak values allows the collection of its values,
but prevents the collection of its keys.
A table with both weak keys and weak values allows the collection of
both keys and values.
In any case, if either the key or the value is collected,
the whole pair is removed from the table.
The weakness of a table is controlled by the
__mode field of its metatable.
-If the __mode field is a string containing the character 'k',
-the keys in the table are weak.
-If __mode contains 'v',
-the values in the table are weak.
+This metavalue, if present, must be one of the following strings:
+"k", for a table with weak keys;
+"v", for a table with weak values;
+or "kv", for a table with both weak keys and values.
A table with weak keys and strong values is also called an ephemeron table. In an ephemeron table, a value is considered reachable only if its key is reachable. In particular, if the only reference to a key comes through its value, the pair is removed.
Any change in the weakness of a table may take effect only at the next collect cycle. In particular, if you change the weakness to a stronger mode, Lua may still collect some items from that table before the change takes effect.
Only objects that have an explicit construction are removed from weak tables. Values, such as numbers and light C functions, are not subject to garbage collection, and therefore are not removed from weak tables (unless their associated values are collected). Although strings are subject to garbage collection, -they do not have an explicit construction, -and therefore are not removed from weak tables. +they do not have an explicit construction and +their equality is by value; +they behave more like values than like objects. +Therefore, they are not removed from weak tables.
Resurrected objects (that is, objects being finalized and objects accessible only through objects being finalized) have a special behavior in weak tables. They are removed from weak values before running their finalizers, but are removed from weak keys only in the next collection after running their finalizers, when such objects are actually freed. This behavior allows the finalizer to access properties associated with the object through weak tables.
If a weak table is among the resurrected objects in a collection cycle, it may not be properly cleared until the next cycle.
Lua supports coroutines, also called collaborative multithreading. A coroutine in Lua represents an independent thread of execution. Unlike threads in multithread systems, however, a coroutine only suspends its execution by explicitly calling a yield function.
You create a coroutine by calling coroutine.create.
Its sole argument is a function
that is the main function of the coroutine.
The create function only creates a new coroutine and
returns a handle to it (an object of type thread);
it does not start the coroutine.
You execute a coroutine by calling coroutine.resume.
When you first call coroutine.resume,
passing as its first argument
a thread returned by coroutine.create,
the coroutine starts its execution by
calling its main function.
Extra arguments passed to coroutine.resume are passed
as arguments to that function.
After the coroutine starts running,
it runs until it terminates or yields.
A coroutine can terminate its execution in two ways:
normally, when its main function returns
(explicitly or implicitly, after the last instruction);
and abnormally, if there is an unprotected error.
In case of normal termination,
coroutine.resume returns true,
plus any values returned by the coroutine main function.
In case of errors, coroutine.resume returns false
-plus an error object.
+plus the error object.
+In this case, the coroutine does not unwind its stack,
+so that it is possible to inspect it after the error
+with the debug API.
A coroutine yields by calling coroutine.yield.
When a coroutine yields,
the corresponding coroutine.resume returns immediately,
even if the yield happens inside nested function calls
(that is, not in the main function,
but in a function directly or indirectly called by the main function).
In the case of a yield, coroutine.resume also returns true,
plus any values passed to coroutine.yield.
The next time you resume the same coroutine,
it continues its execution from the point where it yielded,
with the call to coroutine.yield returning any extra
arguments passed to coroutine.resume.
Like coroutine.create,
the coroutine.wrap function also creates a coroutine,
but instead of returning the coroutine itself,
it returns a function that, when called, resumes the coroutine.
Any arguments passed to this function
go as extra arguments to coroutine.resume.
coroutine.wrap returns all the values returned by coroutine.resume,
except the first one (the boolean error code).
Unlike coroutine.resume,
-coroutine.wrap does not catch errors;
-any error is propagated to the caller.
+the function created by coroutine.wrap
+propagates any error to the caller.
+In this case,
+the function also closes the coroutine (see coroutine.close).
As an example of how coroutines work, consider the following code:
function foo (a)
print("foo", a)
return coroutine.yield(2*a)
end
co = coroutine.create(function (a,b)
print("co-body", a, b)
local r = foo(a+1)
print("co-body", r)
local r, s = coroutine.yield(a+b, a-b)
print("co-body", r, s)
return b, "end"
end)
print("main", coroutine.resume(co, 1, 10))
print("main", coroutine.resume(co, "r"))
print("main", coroutine.resume(co, "x", "y"))
print("main", coroutine.resume(co, "x", "y"))
When you run it, it produces the following output:
co-body 1 10
foo 2
main true 4
co-body r
main true 11 -9
co-body x y
main true 10 end
main false cannot resume dead coroutine
You can also create and manipulate coroutines through the C API:
see functions lua_newthread, lua_resume,
and lua_yield.
This section describes the lexis, the syntax, and the semantics of Lua. In other words, this section describes which tokens are valid, how they can be combined, and what their combinations mean.
Language constructs will be explained using the usual extended BNF notation, in which {a} means 0 or more a's, and [a] means an optional a. Non-terminals are shown like non-terminal, keywords are shown like kword, and other terminal symbols are shown like ‘=’. The complete syntax of Lua can be found in §9 at the end of this manual. + +
Lua is a free-form language. -It ignores spaces (including new lines) and comments -between lexical elements (tokens), -except as delimiters between names and keywords. +It ignores spaces and comments between lexical elements (tokens), +except as delimiters between two tokens. +In source code, +Lua recognizes as spaces the standard ASCII whitespace +characters space, form feed, newline, +carriage return, horizontal tab, and vertical tab.
Names (also called identifiers) -in Lua can be any string of letters, -digits, and underscores, +in Lua can be any string of Latin letters, +Arabic-Indic digits, and underscores, not beginning with a digit and not being a reserved word. Identifiers are used to name variables, table fields, and labels.
The following keywords are reserved and cannot be used as names:
and break do else elseif end
false for function goto if in
local nil not or repeat return
then true until while
Lua is a case-sensitive language:
and is a reserved word, but And and AND
are two different, valid names.
As a convention,
programs should avoid creating
names that start with an underscore followed by
one or more uppercase letters (such as _VERSION).
The following strings denote other tokens:
+ - * / % ^ #
& ~ | << >> //
== ~= <= >= < > =
( ) { } [ ] ::
; : , . .. ...
A short literal string
can be delimited by matching single or double quotes,
and can contain the following C-like escape sequences:
'\a' (bell),
'\b' (backspace),
'\f' (form feed),
'\n' (newline),
'\r' (carriage return),
'\t' (horizontal tab),
'\v' (vertical tab),
'\\' (backslash),
'\"' (quotation mark [double quote]),
and '\'' (apostrophe [single quote]).
A backslash followed by a line break
results in a newline in the string.
The escape sequence '\z' skips the following span
-of white-space characters,
+of whitespace characters,
including line breaks;
it is particularly useful to break and indent a long literal string
into multiple lines without adding the newlines and spaces
into the string contents.
A short literal string cannot contain unescaped line breaks
nor escapes not forming a valid escape sequence.
-We can specify any byte in a short literal string by its numeric value
-(including embedded zeros).
+We can specify any byte in a short literal string,
+including embedded zeros,
+by its numeric value.
This can be done
with the escape sequence \xXX,
where XX is a sequence of exactly two hexadecimal digits,
or with the escape sequence \ddd,
where ddd is a sequence of up to three decimal digits.
(Note that if a decimal escape sequence is to be followed by a digit,
it must be expressed using exactly three digits.)
The UTF-8 encoding of a Unicode character
can be inserted in a literal string with
the escape sequence \u{XXX}
-(note the mandatory enclosing brackets),
+(with mandatory enclosing braces),
where XXX is a sequence of one or more hexadecimal digits
representing the character code point.
+This code point can be any value less than 231.
+(Lua uses the original UTF-8 specification here,
+which is not restricted to valid Unicode code points.)
Literal strings can also be defined using a long format
enclosed by long brackets.
We define an opening long bracket of level n as an opening
square bracket followed by n equal signs followed by another
opening square bracket.
So, an opening long bracket of level 0 is written as [[,
an opening long bracket of level 1 is written as [=[,
and so on.
A closing long bracket is defined similarly;
for instance,
a closing long bracket of level 4 is written as ]====].
A long literal starts with an opening long bracket of any level and
ends at the first closing long bracket of the same level.
It can contain any text except a closing bracket of the same level.
Literals in this bracketed form can run for several lines,
do not interpret any escape sequences,
and ignore long brackets of any other level.
Any kind of end-of-line sequence
(carriage return, newline, carriage return followed by newline,
or newline followed by carriage return)
is converted to a simple newline.
+When the opening long bracket is immediately followed by a newline,
+the newline is not included in the string.
-For convenience,
-when the opening long bracket is immediately followed by a newline,
-the newline is not included in the string.
As an example, in a system using ASCII
(in which 'a' is coded as 97,
newline is coded as 10, and '1' is coded as 49),
the five literal strings below denote the same string:
a = 'alo\n123"'
a = "alo\n123\""
a = '\97lo\10\04923"'
a = [[alo
123"]]
a = [==[
alo
123"]==]
Any byte in a literal string not explicitly affected by the previous rules represents itself. However, Lua opens files for parsing in text mode, -and the system file functions may have problems with +and the system's file functions may have problems with some control characters. So, it is safer to represent -non-text data as a quoted literal with +binary data as a quoted literal with explicit escape sequences for the non-text characters.
A numeric constant (or numeral)
can be written with an optional fractional part
and an optional decimal exponent,
marked by a letter 'e' or 'E'.
Lua also accepts hexadecimal constants,
which start with 0x or 0X.
Hexadecimal constants also accept an optional fractional part
plus an optional binary exponent,
marked by a letter 'p' or 'P'.
+
+
+
A numeric constant with a radix point or an exponent denotes a float; otherwise, -if its value fits in an integer, -it denotes an integer. +if its value fits in an integer or it is a hexadecimal constant, +it denotes an integer; +otherwise (that is, a decimal integer numeral that overflows), +it denotes a float. +Hexadecimal numerals with neither a radix point nor an exponent +always denote an integer value; +if the value overflows, it wraps around +to fit into a valid integer. + + +
Examples of valid integer constants are
3 345 0xff 0xBEBADA
Examples of valid float constants are
3.0 3.1416 314.16e-2 0.31416E1 34e1
0x0.1E 0xA23p-4 0X1.921FB54442D18P+1
A comment starts with a double hyphen (--)
anywhere outside a string.
If the text immediately after -- is not an opening long bracket,
the comment is a short comment,
which runs until the end of the line.
Otherwise, it is a long comment,
which runs until the corresponding closing long bracket.
-Long comments are frequently used to disable code temporarily.
Variables are places that store values. There are three kinds of variables in Lua: global variables, local variables, and table fields.
A single name can denote a global variable or a local variable (or a function's formal parameter, which is a particular kind of local variable):
var ::= Name
-Name denotes identifiers, as defined in §3.1. +Name denotes identifiers (see §3.1).
Any variable name is assumed to be global unless explicitly declared as a local (see §3.3.7). Local variables are lexically scoped: local variables can be freely accessed by functions defined inside their scope (see §3.5).
Before the first assignment to a variable, its value is nil.
Square brackets are used to index a table:
var ::= prefixexp ‘[’ exp ‘]’
The meaning of accesses to table fields can be changed via metatables (see §2.4).
The syntax var.Name is just syntactic sugar for
var["Name"]:
var ::= prefixexp ‘.’ Name
An access to a global variable x
is equivalent to _ENV.x.
Due to the way that chunks are compiled,
-_ENV is never a global name (see §2.2).
+the variable _ENV itself is never global (see §2.2).
Lua supports an almost conventional set of statements, -similar to those in Pascal or C. +similar to those in other conventional languages. This set includes -assignments, control structures, function calls, +blocks, assignments, control structures, function calls, and variable declarations. + +
A block is a list of statements, which are executed sequentially:
block ::= {stat}
Lua has empty statements that allow you to separate statements with semicolons, start a block with a semicolon or write two semicolons in sequence:
stat ::= ‘;’
-Function calls and assignments +Both function calls and assignments can start with an open parenthesis. This possibility leads to an ambiguity in Lua's grammar. Consider the following fragment:
a = b + c
(print or io.write)('done')
-The grammar could see it in two ways: +The grammar could see this fragment in two ways:
a = b + c(print or io.write)('done')
a = b + c; (print or io.write)('done')
The current parser always sees such constructions in the first way, interpreting the open parenthesis as the start of the arguments to a call. To avoid this ambiguity, it is a good practice to always precede with a semicolon statements that start with a parenthesis:
;(print or io.write)('done')
A block can be explicitly delimited to produce a single statement:
stat ::= do block end
Explicit blocks are useful to control the scope of variable declarations. Explicit blocks are also sometimes used to add a return statement in the middle of another block (see §3.3.4).
The unit of compilation of Lua is called a chunk. Syntactically, a chunk is simply a block:
chunk ::= block
Lua handles a chunk as the body of an anonymous function
with a variable number of arguments
(see §3.4.11).
As such, chunks can define local variables,
receive arguments, and return values.
Moreover, such anonymous function is compiled as in the
scope of an external local variable called _ENV (see §2.2).
-The resulting function always has _ENV as its only upvalue,
+The resulting function always has _ENV as its only external variable,
even if it does not use that variable.
A chunk can be stored in a file or in a string inside the host program. To execute a chunk, Lua first loads it, precompiling the chunk's code into instructions for a virtual machine, and then Lua executes the compiled code with an interpreter for the virtual machine.
Chunks can also be precompiled into binary form;
-see program luac and function string.dump for details.
+see the program luac and the function string.dump for details.
Programs in source and compiled forms are interchangeable;
Lua automatically detects the file type and acts accordingly (see load).
Lua allows multiple assignments. Therefore, the syntax for assignment defines a list of variables on the left side and a list of expressions on the right side. The elements in both lists are separated by commas:
stat ::= varlist ‘=’ explist
varlist ::= var {‘,’ var}
explist ::= exp {‘,’ exp}
Expressions are discussed in §3.4.
Before the assignment, the list of values is adjusted to the length of the list of variables. If there are more values than needed, the excess values are thrown away. If there are fewer values than needed, -the list is extended with as many nil's as needed. +the list is extended with nil's. If the list of expressions ends with a function call, then all values returned by that call enter the list of values, before the adjustment (except when the call is enclosed in parentheses; see §3.4).
The assignment statement first evaluates all its expressions and only then the assignments are performed. Thus the code
i = 3
i, a[i] = i+1, 20
sets a[3] to 20, without affecting a[4]
because the i in a[i] is evaluated (to 3)
before it is assigned 4.
Similarly, the line
x, y = y, x
exchanges the values of x and y,
and
x, y, z = y, z, x
cyclically permutes the values of x, y, and z.
An assignment to a global name x = val
is equivalent to the assignment
_ENV.x = val (see §2.2).
The meaning of assignments to table fields and global variables (which are actually table fields, too) can be changed via metatables (see §2.4).
The control structures if, while, and repeat have the usual meaning and familiar syntax:
stat ::= while exp do block end
stat ::= repeat block until exp
stat ::= if exp then block {elseif exp then block} [else block] end
Lua also has a for statement, in two flavors (see §3.3.5).
The condition expression of a control structure can return any value. -Both false and nil are considered false. -All values different from nil and false are considered true -(in particular, the number 0 and the empty string are also true). +Both false and nil test false. +All values different from nil and false test true. +In particular, the number 0 and the empty string also test true.
In the repeat–until loop, the inner block does not end at the until keyword, but only after the condition. So, the condition can refer to local variables declared inside the loop block.
The goto statement transfers the program control to a label. For syntactical reasons, labels in Lua are considered statements too:
stat ::= goto Name stat ::= label label ::= ‘::’ Name ‘::’
A label is visible in the entire block where it is defined, -except -inside nested blocks where a label with the same name is defined and -inside nested functions. +except inside nested functions. A goto may jump to any visible label as long as it does not enter into the scope of a local variable. +A label should not be declared +where a label with the same name is visible, +even if this other label has been declared in an enclosing block.
Labels and empty statements are called void statements, as they perform no actions.
The break statement terminates the execution of a while, repeat, or for loop, skipping to the next statement after the loop:
stat ::= break
A break ends the innermost enclosing loop.
The return statement is used to return values from a function or a chunk -(which is an anonymous function). +(which is handled as an anonymous function). Functions can return more than one value, so the syntax for the return statement is
stat ::= return [explist] [‘;’]
The return statement can only be written
as the last statement of a block.
-If it is really necessary to return in the middle of a block,
+If it is necessary to return in the middle of a block,
then an explicit inner block can be used,
as in the idiom do return end,
because now return is the last statement in its (inner) block.
The for statement has two forms: one numerical and one generic. + +
The numerical for loop repeats a block of code while a -control variable runs through an arithmetic progression. +control variable goes through an arithmetic progression. It has the following syntax:
stat ::= for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end
-The block is repeated for name starting at the value of -the first exp, until it passes the second exp by steps of the -third exp. -More precisely, a for statement like +The given identifier (Name) defines the control variable, +which is a new variable local to the loop body (block). -
- for v = e1, e2, e3 do block end -
-is equivalent to the code: -
- do - local var, limit, step = tonumber(e1), tonumber(e2), tonumber(e3) - if not (var and limit and step) then error() end - var = var - step - while true do - var = var + step - if (step >= 0 and var > limit) or (step < 0 and var < limit) then - break - end - local v = var - block - end - end -+
+The loop starts by evaluating once the three control expressions. +Their values are called respectively +the initial value, the limit, and the step. +If the step is absent, it defaults to 1. +
-Note the following: +If both the initial value and the step are integers, +the loop is done with integers; +note that the limit may not be an integer. +Otherwise, the three values are converted to +floats and the loop is done with floats. +Beware of floating-point accuracy in this case. -
+After that initialization, +the loop body is repeated with the value of the control variable +going through an arithmetic progression, +starting at the initial value, +with a common difference given by the step. +A negative step makes a decreasing sequence; +a step equal to zero raises an error. +The loop continues while the value is less than +or equal to the limit +(greater than or equal to for a negative step). +If the initial value is already greater than the limit +(or less than, if the step is negative), +the body is not executed. -
var, limit, and step are invisible variables.
-The names shown here are for explanatory purposes only.
-+For integer loops, +the control variable never wraps around; +instead, the loop ends in case of an overflow. -
v is local to the loop body.
++You should not change the value of the control variable +during the loop. If you need its value after the loop, assign it to another variable before exiting the loop. -
The generic for statement works over functions, called iterators. On each iteration, the iterator function is called to produce a new value, stopping when this new value is nil. The generic for loop has the following syntax:
stat ::= for namelist in explist do block end
namelist ::= Name {‘,’ Name}
A for statement like
- for var_1, ···, var_n in explist do block end + for var_1, ···, var_n in explist do body end
-is equivalent to the code: +works as follows. -
- do - local f, s, var = explist - while true do - local var_1, ···, var_n = f(s, var) - if var_1 == nil then break end - var = var_1 - block - end - end -
-Note the following: -
+The names var_i declare loop variables local to the loop body. +The first of these variables is the control variable. -
explist is evaluated only once.
-Its results are an iterator function,
+
++The loop starts by evaluating explist +to produce four values: +an iterator function, a state, -and an initial value for the first iterator variable. -
f, s, and var are invisible variables.
-The names are here for explanatory purposes only.
-+Then, at each iteration, +Lua calls the iterator function with two arguments: +the state and the control variable. +The results from this call are then assigned to the loop variables, +following the rules of multiple assignments (see §3.3.3). +If the control variable becomes nil, +the loop terminates. +Otherwise, the body is executed and the loop goes +to the next iteration. + + +
+The closing value behaves like a +to-be-closed variable (see §3.3.8), +which can be used to release resources when the loop ends. +Otherwise, it does not interfere with the loop. + + +
+You should not change the value of the control variable +during the loop. + -
var_i are local to the loop;
-you cannot use their values after the for ends.
-If you need these values,
-then assign them to other variables before breaking or exiting the loop.
-To allow possible side-effects, function calls can be executed as statements:
stat ::= functioncall
In this case, all returned values are thrown away. Function calls are explained in §3.4.10.
Local variables can be declared anywhere inside a block. -The declaration can include an initial assignment: +The declaration can include an initialization:
- stat ::= local namelist [‘=’ explist]
+ stat ::= local attnamelist [‘=’ explist]
+ attnamelist ::= Name attrib {‘,’ Name attrib}
If present, an initial assignment has the same semantics of a multiple assignment (see §3.3.3). Otherwise, all variables are initialized with nil. +
+Each variable name may be postfixed by an attribute +(a name between angle brackets): + +
+ attrib ::= [‘<’ Name ‘>’] +
+There are two possible attributes:
+const, which declares a constant variable,
+that is, a variable that cannot be assigned to
+after its initialization;
+and close, which declares a to-be-closed variable (see §3.3.8).
+A list of variables can contain at most one to-be-closed variable.
+
+
A chunk is also a block (see §3.3.2), and so local variables can be declared in a chunk outside any explicit block.
The visibility rules for local variables are explained in §3.5. +
+A to-be-closed variable behaves like a constant local variable, +except that its value is closed whenever the variable +goes out of scope, including normal block termination, +exiting its block by break/goto/return, +or exiting by an error. + + +
+Here, to close a value means
+to call its __close metamethod.
+When calling the metamethod,
+the value itself is passed as the first argument
+and the error object that caused the exit (if any)
+is passed as a second argument;
+if there was no error, the second argument is nil.
+
+
+
+The value assigned to a to-be-closed variable
+must have a __close metamethod
+or be a false value.
+(nil and false are ignored as to-be-closed values.)
+
+
+
+If several to-be-closed variables go out of scope at the same event, +they are closed in the reverse order that they were declared. + + +
+If there is any error while running a closing method, +that error is handled like an error in the regular code +where the variable was defined. +However, Lua may call the method one more time. + + +
+After an error, +the other pending closing methods will still be called. +Errors in these methods +interrupt the respective method and generate a warning, +but are otherwise ignored; +the error reported is only the original one. + + +
+If a coroutine yields and is never resumed again,
+some variables may never go out of scope,
+and therefore they will never be closed.
+(These variables are the ones created inside the coroutine
+and in scope at the point where the coroutine yielded.)
+Similarly, if a coroutine ends with an error,
+it does not unwind its stack,
+so it does not close any variable.
+In both cases,
+you can either use finalizers
+or call coroutine.close to close the variables.
+However, if the coroutine was created
+through coroutine.wrap,
+then its corresponding function will close the coroutine
+in case of errors.
+
+
+
+
+
The basic expressions in Lua are the following:
exp ::= prefixexp exp ::= nil | false | true exp ::= Numeral exp ::= LiteralString exp ::= functiondef exp ::= tableconstructor exp ::= ‘...’ exp ::= exp binop exp exp ::= unop exp prefixexp ::= var | functioncall | ‘(’ exp ‘)’
Numerals and literal strings are explained in §3.1;
variables are explained in §3.2;
function definitions are explained in §3.4.11;
function calls are explained in §3.4.10;
table constructors are explained in §3.4.9.
Vararg expressions,
denoted by three dots ('...'), can only be used when
directly inside a vararg function;
they are explained in §3.4.11.
Binary operators comprise arithmetic operators (see §3.4.1), bitwise operators (see §3.4.2), relational operators (see §3.4.4), logical operators (see §3.4.5), and the concatenation operator (see §3.4.6). Unary operators comprise the unary minus (see §3.4.1), the unary bitwise NOT (see §3.4.2), the unary logical not (see §3.4.5), and the unary length operator (see §3.4.7).
Both function calls and vararg expressions can result in multiple values. If a function call is used as a statement (see §3.3.6), then its return list is adjusted to zero elements, thus discarding all returned values. If an expression is used as the last (or the only) element of a list of expressions, then no adjustment is made (unless the expression is enclosed in parentheses). In all other contexts, Lua adjusts the result list to one element, either discarding all values except the first one or adding a single nil if there are no values.
Here are some examples:
f() -- adjusted to 0 results
g(f(), x) -- f() is adjusted to 1 result
g(x, f()) -- g gets x plus all results from f()
a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil)
a,b = ... -- a gets the first vararg argument, b gets
-- the second (both a and b can get nil if there
-- is no corresponding vararg argument)
a,b,c = x, f() -- f() is adjusted to 2 results
a,b,c = f() -- f() is adjusted to 3 results
return f() -- returns all results from f()
return ... -- returns all received vararg arguments
return x,y,f() -- returns x, y, and all results from f()
{f()} -- creates a list with all results from f()
{...} -- creates a list with all vararg arguments
{f(), nil} -- f() is adjusted to 1 result
Any expression enclosed in parentheses always results in only one value.
Thus,
(f(x,y,z)) is always a single value,
even if f returns several values.
(The value of (f(x,y,z)) is the first value returned by f
or nil if f does not return any values.)
+
+
Lua supports the following arithmetic operators:
+: addition-: subtraction*: multiplication/: float division//: floor division%: modulo^: exponentiation-: unary minusWith the exception of exponentiation and float division, the arithmetic operators work as follows: If both operands are integers, the operation is performed over integers and the result is an integer. -Otherwise, if both operands are numbers -or strings that can be converted to -numbers (see §3.4.3), +Otherwise, if both operands are numbers, then they are converted to floats, -the operation is performed following the usual rules +the operation is performed following the machine's rules for floating-point arithmetic (usually the IEEE 754 standard), and the result is a float. +(The string library coerces strings to numbers in +arithmetic operations; see §3.4.3 for details.)
Exponentiation and float division (/)
always convert their operands to floats
and the result is always a float.
Exponentiation uses the ISO C function pow,
so that it works for non-integer exponents too.
Floor division (//) is a division
that rounds the quotient towards minus infinity,
-that is, the floor of the division of its operands.
+resulting in the floor of the division of its operands.
Modulo is defined as the remainder of a division that rounds the quotient towards minus infinity (floor division).
In case of overflows in integer arithmetic, -all operations wrap around, -according to the usual rules of two-complement arithmetic. -(In other words, -they return the unique representable integer -that is equal modulo 264 to the mathematical result.) +all operations wrap around.
Lua supports the following bitwise operators:
&: bitwise AND|: bitwise OR~: bitwise exclusive OR>>: right shift<<: left shift~: unary bitwise NOTAll bitwise operations convert its operands to integers (see §3.4.3), operate on all bits of those integers, and result in an integer.
Both right and left shifts fill the vacant bits with zeros. Negative displacements shift to the other direction; displacements with absolute values equal to or higher than the number of bits in an integer result in zero (as all bits are shifted out).
Lua provides some automatic conversions between some types and representations at run time. Bitwise operators always convert float operands to integers. Exponentiation and float division always convert integer operands to floats. All other arithmetic operations applied to mixed numbers -(integers and floats) convert the integer operand to a float; -this is called the usual rule. +(integers and floats) convert the integer operand to a float. The C API also converts both integers to floats and floats to integers, as needed. Moreover, string concatenation accepts numbers as arguments, besides strings. -
-Lua also converts strings to numbers, -whenever a number is expected. - -
In a conversion from integer to float, if the integer value has an exact representation as a float, that is the result. Otherwise, the conversion gets the nearest higher or the nearest lower representable value. This kind of conversion never fails.
The conversion from float to integer checks whether the float has an exact representation as an integer (that is, the float has an integral value and it is in the range of integer representation). If it does, that representation is the result. Otherwise, the conversion fails.
-The conversion from strings to numbers goes as follows: -First, the string is converted to an integer or a float, -following its syntax and the rules of the Lua lexer. -(The string may have also leading and trailing spaces and a sign.) -Then, the resulting number (float or integer) -is converted to the type (float or integer) required by the context -(e.g., the operation that forced the conversion). +Several places in Lua coerce strings to numbers when necessary. +In particular, +the string library sets metamethods that try to coerce +strings to numbers in all arithmetic operations. +If the conversion fails, +the library calls the metamethod of the other operand +(if present) or it raises an error. +Note that bitwise operators do not do this coercion.
+Nonetheless, it is always a good practice not to rely on these
+implicit coercions, as they are not always applied;
+in particular, "1"==1 is false and "1"<1 raises an error
+(see §3.4.4).
+These coercions exist mainly for compatibility and may be removed
+in future versions of the language.
+
+
+
+A string is converted to an integer or a float +following its syntax and the rules of the Lua lexer. +The string may have also leading and trailing whitespaces and a sign. All conversions from strings to numbers accept both a dot and the current locale mark as the radix character. (The Lua lexer, however, accepts only a dot.) +If the string is not a valid numeral, +the conversion fails. +If necessary, the result of this first step is then converted +to a specific number subtype following the previous rules +for conversions between floats and integers.
The conversion from numbers to strings uses a
non-specified human-readable format.
-For complete control over how numbers are converted to strings,
-use the format function from the string library
-(see string.format).
+To convert numbers to strings in any specific way,
+use the function string.format.
Lua supports the following relational operators:
==: equality~=: inequality<: less than>: greater than<=: less or equal>=: greater or equalThese operators always result in false or true.
Equality (==) first compares the type of its operands.
If the types are different, then the result is false.
Otherwise, the values of the operands are compared.
-Strings are compared in the obvious way.
+Strings are equal if they have the same byte content.
Numbers are equal if they denote the same mathematical value.
Tables, userdata, and threads are compared by reference: two objects are considered equal only if they are the same object. Every time you create a new object -(a table, userdata, or thread), +(a table, a userdata, or a thread), this new object is different from any previously existing object. -A closure is always equal to itself. -Closures with any detectable difference +A function is always equal to itself. +Functions with any detectable difference (different behavior, different definition) are always different. -Closures created at different times but with no detectable differences +Functions created at different times but with no detectable differences may be classified as equal or not (depending on internal caching details).
You can change the way that Lua compares tables and userdata
-by using the "eq" metamethod (see §2.4).
+by using the __eq metamethod (see §2.4).
Equality comparisons do not convert strings to numbers
or vice versa.
Thus, "0"==0 evaluates to false,
and t[0] and t["0"] denote different
entries in a table.
The operator ~= is exactly the negation of equality (==).
The order operators work as follows.
If both arguments are numbers,
-then they are compared according to their mathematical values
-(regardless of their subtypes).
+then they are compared according to their mathematical values,
+regardless of their subtypes.
Otherwise, if both arguments are strings,
then their values are compared according to the current locale.
-Otherwise, Lua tries to call the "lt" or the "le"
+Otherwise, Lua tries to call the __lt or the __le
metamethod (see §2.4).
A comparison a > b is translated to b < a
and a >= b is translated to b <= a.
Following the IEEE 754 standard, -NaN is considered neither smaller than, -nor equal to, nor greater than any value (including itself). +the special value NaN is considered neither less than, +nor equal to, nor greater than any value, including itself.
The logical operators in Lua are and, or, and not. Like the control structures (see §3.3.4), all logical operators consider both false and nil as false and anything else as true.
The negation operator not always returns false or true. The conjunction operator and returns its first argument if this value is false or nil; otherwise, and returns its second argument. The disjunction operator or returns its first argument if this value is different from nil and false; otherwise, or returns its second argument. Both and and or use short-circuit evaluation; that is, the second operand is evaluated only if necessary. Here are some examples:
10 or 20 --> 10
10 or error() --> 10
nil or "a" --> "a"
nil and 10 --> nil
false and error() --> false
false and nil --> false
false or nil --> nil
10 and 20 --> 20
-
-(In this manual,
---> indicates the result of the preceding expression.)
-
+
The string concatenation operator in Lua is
denoted by two dots ('..').
-If both operands are strings or numbers, then they are converted to
-strings according to the rules described in §3.4.3.
+If both operands are strings or numbers,
+then the numbers are converted to strings
+in a non-specified format (see §3.4.3).
Otherwise, the __concat metamethod is called (see §2.4).
The length operator is denoted by the unary prefix operator #.
-The length of a string is its number of bytes -(that is, the usual meaning of string length when each -character is one byte). +The length of a string is its number of bytes. +(That is the usual meaning of string length when each +character is one byte.)
The length operator applied on a table
returns a border in that table.
A border in a table t is any natural number
that satisfies the following condition:
(border == 0 or t[border] ~= nil) and t[border + 1] == nil
In words, -a border is any (natural) index in a table -where a non-nil value is followed by a nil value -(or zero, when index 1 is nil). +a border is any (natural) index present in the table +that is followed by an absent index +(or zero, when index 1 is absent).
A table with exactly one border is called a sequence.
For instance, the table {10, 20, 30, 40, 50} is a sequence,
as it has only one border (5).
The table {10, 20, 30, nil, 50} has two borders (3 and 5),
and therefore it is not a sequence.
+(The nil at index 4 is called a hole.)
The table {nil, 20, 30, nil, nil, 60, nil}
-has three borders (0, 3, and 6),
+has three borders (0, 3, and 6) and three holes
+(at indices 1, 4, and 5),
so it is not a sequence, too.
The table {} is a sequence with border 0.
Note that non-natural keys do not interfere
with whether a table is a sequence.
When t is a sequence,
#t returns its only border,
which corresponds to the intuitive notion of the length of the sequence.
When t is not a sequence,
#t can return any of its borders.
(The exact one depends on details of
the internal representation of the table,
which in turn can depend on how the table was populated and
the memory addresses of its non-numeric keys.)
The computation of the length of a table has a guaranteed worst time of O(log n), where n is the largest natural key in the table.
A program can modify the behavior of the length operator for
any value but strings through the __len metamethod (see §2.4).
Operator precedence in Lua follows the table below, from lower to higher priority:
or
and
< > <= >= ~= ==
|
~
&
<< >>
..
+ -
* / // %
unary operators (not # - ~)
^
As usual,
you can use parentheses to change the precedences of an expression.
The concatenation ('..') and exponentiation ('^')
operators are right associative.
All other binary operators are left associative.
Table constructors are expressions that create tables. Every time a constructor is evaluated, a new table is created. A constructor can be used to create an empty table or to create a table and initialize some of its fields. The general syntax for constructors is
tableconstructor ::= ‘{’ [fieldlist] ‘}’
fieldlist ::= field {fieldsep field} [fieldsep]
field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
fieldsep ::= ‘,’ | ‘;’
Each field of the form [exp1] = exp2 adds to the new table an entry
with key exp1 and value exp2.
A field of the form name = exp is equivalent to
["name"] = exp.
-Finally, fields of the form exp are equivalent to
+Fields of the form exp are equivalent to
[i] = exp, where i are consecutive integers
-starting with 1.
-Fields in the other formats do not affect this counting.
+starting with 1;
+fields in the other formats do not affect this counting.
For example,
a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 }
is equivalent to
do
local t = {}
t[f(1)] = g
t[1] = "x" -- 1st exp
t[2] = "y" -- 2nd exp
t.x = 1 -- t["x"] = 1
t[3] = f(x) -- 3rd exp
t[30] = 23
t[4] = 45 -- 4th exp
a = t
end
The order of the assignments in a constructor is undefined. (This order would be relevant only when there are repeated keys.)
If the last field in the list has the form exp
and the expression is a function call or a vararg expression,
then all values returned by this expression enter the list consecutively
(see §3.4.10).
The field list can have an optional trailing separator, as a convenience for machine-generated code.
A function call in Lua has the following syntax:
functioncall ::= prefixexp args
In a function call,
first prefixexp and args are evaluated.
If the value of prefixexp has type function,
then this function is called
with the given arguments.
-Otherwise, the prefixexp "call" metamethod is called,
-having as first argument the value of prefixexp,
+Otherwise, if present,
+the prefixexp __call metamethod is called:
+its first argument is the value of prefixexp,
followed by the original call arguments
(see §2.4).
The form
functioncall ::= prefixexp ‘:’ Name args
-can be used to call "methods".
+can be used to emulate methods.
A call v:name(args)
is syntactic sugar for v.name(v,args),
except that v is evaluated only once.
Arguments have the following syntax:
args ::= ‘(’ [explist] ‘)’ args ::= tableconstructor args ::= LiteralString
All argument expressions are evaluated before the call.
A call of the form f{fields} is
syntactic sugar for f({fields});
that is, the argument list is a single new table.
A call of the form f'string'
(or f"string" or f[[string]])
is syntactic sugar for f('string');
that is, the argument list is a single literal string.
-A call of the form return functioncall is called
-a tail call.
+A call of the form return functioncall not in the
+scope of a to-be-closed variable is called a tail call.
Lua implements proper tail calls
(or proper tail recursion):
in a tail call,
the called function reuses the stack entry of the calling function.
Therefore, there is no limit on the number of nested tail calls that
a program can execute.
However, a tail call erases any debug information about the
calling function.
Note that a tail call only happens with a particular syntax,
-where the return has one single function call as argument;
-this syntax makes the calling function return exactly
-the returns of the called function.
+where the return has one single function call as argument,
+and it is outside the scope of any to-be-closed variable.
+This syntax makes the calling function return exactly
+the returns of the called function,
+without any intervening action.
So, none of the following examples are tail calls:
return (f(x)) -- results adjusted to 1
- return 2 * f(x)
+ return 2 * f(x) -- result multiplied by 2
return x, f(x) -- additional results
f(x); return -- results discarded
return x or f(x) -- results adjusted to 1
The syntax for function definition is
functiondef ::= function funcbody funcbody ::= ‘(’ [parlist] ‘)’ block end
The following syntactic sugar simplifies function definitions:
stat ::= function funcname funcbody
stat ::= local function Name funcbody
funcname ::= Name {‘.’ Name} [‘:’ Name]
The statement
function f () body end
translates to
f = function () body end
The statement
function t.a.b.c.f () body end
translates to
t.a.b.c.f = function () body end
The statement
local function f () body end
translates to
local f; f = function () body end
not to
local f = function () body end
(This only makes a difference when the body of the function
contains references to f.)
A function definition is an executable expression, whose value has type function. When Lua precompiles a chunk, -all its function bodies are precompiled too. +all its function bodies are precompiled too, +but they are not created yet. Then, whenever Lua executes the function definition, the function is instantiated (or closed). -This function instance (or closure) +This function instance, or closure, is the final value of the expression.
Parameters act as local variables that are initialized with the argument values:
parlist ::= namelist [‘,’ ‘...’] | ‘...’
-When a function is called,
-the list of arguments is adjusted to
-the length of the list of parameters,
+When a Lua function is called,
+it adjusts its list of arguments to
+the length of its list of parameters,
unless the function is a vararg function,
which is indicated by three dots ('...')
at the end of its parameter list.
A vararg function does not adjust its argument list;
instead, it collects all extra arguments and supplies them
to the function through a vararg expression,
which is also written as three dots.
The value of this expression is a list of all actual extra arguments,
similar to a function with multiple results.
If a vararg expression is used inside another expression
or in the middle of a list of expressions,
then its return list is adjusted to one element.
If the expression is used as the last element of a list of expressions,
then no adjustment is made
(unless that last expression is enclosed in parentheses).
As an example, consider the following definitions:
function f(a, b) end
function g(a, b, ...) end
function r() return 1,2,3 end
Then, we have the following mapping from arguments to parameters and to the vararg expression:
- CALL PARAMETERS
+ CALL PARAMETERS
f(3) a=3, b=nil
f(3, 4) a=3, b=4
f(3, 4, 5) a=3, b=4
f(r(), 10) a=1, b=10
f(r()) a=1, b=2
g(3) a=3, b=nil, ... --> (nothing)
g(3, 4) a=3, b=4, ... --> (nothing)
g(3, 4, 5, 8) a=3, b=4, ... --> 5 8
g(5, r()) a=5, b=1, ... --> 2 3
Results are returned using the return statement (see §3.3.4). If control reaches the end of a function without encountering a return statement, then the function returns with no results.
There is a system-dependent limit on the number of values that a function may return. -This limit is guaranteed to be larger than 1000. +This limit is guaranteed to be greater than 1000.
The colon syntax
-is used for defining methods,
-that is, functions that have an implicit extra parameter self.
+is used to emulate methods,
+adding an implicit extra parameter self to the function.
Thus, the statement
function t.a.b.c:f (params) body end
is syntactic sugar for
t.a.b.c.f = function (self, params) body end
Lua is a lexically scoped language. The scope of a local variable begins at the first statement after its declaration and lasts until the last non-void statement of the innermost block that includes the declaration. Consider the following example:
x = 10 -- global variable
do -- new block
local x = x -- new 'x', with value 10
print(x) --> 10
x = x+1
do -- another block
local x = x+1 -- another 'x'
print(x) --> 12
end
print(x) --> 11
end
print(x) --> 10 (the global one)
Notice that, in a declaration like local x = x,
the new x being declared is not in scope yet,
and so the second x refers to the outside variable.
Because of the lexical scoping rules, local variables can be freely accessed by functions defined inside their scope. -A local variable used by an inner function is called -an upvalue, or external local variable, +A local variable used by an inner function is called an upvalue +(or external local variable, or simply external variable) inside the inner function.
Notice that each execution of a local statement defines new local variables. Consider the following example:
a = {}
local x = 20
- for i=1,10 do
+ for i = 1, 10 do
local y = 0
- a[i] = function () y=y+1; return x+y end
+ a[i] = function () y = y + 1; return x + y end
end
The loop creates ten closures
(that is, ten instances of the anonymous function).
Each of these closures uses a different y variable,
while all of them share the same x.
This section describes the C API for Lua, that is,
the set of C functions available to the host program to communicate
with Lua.
All API functions and related types and constants
are declared in the header file lua.h.
Even when we use the term "function", any facility in the API may be provided as a macro instead. Except where stated otherwise, all such macros use each of their arguments exactly once (except for the first argument, which is always a Lua state), and so do not generate any hidden side-effects.
As in most C libraries,
-the Lua API functions do not check their arguments for validity or consistency.
+the Lua API functions do not check their arguments
+for validity or consistency.
However, you can change this behavior by compiling Lua
with the macro LUA_USE_APICHECK defined.
The Lua library is fully reentrant: it has no global variables. It keeps all information it needs in a dynamic structure, called the Lua state.
Each Lua state has one or more threads,
which correspond to independent, cooperative lines of execution.
The type lua_State (despite its name) refers to a thread.
(Indirectly, through the thread, it also refers to the
Lua state associated to the thread.)
A pointer to a thread must be passed as the first argument to
every function in the library, except to lua_newstate,
which creates a Lua state from scratch and returns a pointer
to the main thread in the new state.
+
+
Lua uses a virtual stack to pass values to and from C. Each element in this stack represents a Lua value (nil, number, string, etc.). Functions in the API can access this stack through the Lua state parameter that they receive.
Whenever Lua calls C, the called function gets a new stack,
which is independent of previous stacks and of stacks of
C functions that are still active.
This stack initially contains any arguments to the C function
and it is where the C function can store temporary
Lua values and must push its results
to be returned to the caller (see lua_CFunction).
For convenience, most query operations in the API do not follow a strict stack discipline. Instead, they can refer to any element in the stack by using an index: -A positive index represents an absolute stack position -(starting at 1); +A positive index represents an absolute stack position, +starting at 1 as the bottom of the stack; a negative index represents an offset relative to the top of the stack. More specifically, if the stack has n elements, then index 1 represents the first element (that is, the element that was pushed onto the stack first) and index n represents the last element; index -1 also represents the last element (that is, the element at the top) and index -n represents the first element. -
When you interact with the Lua API,
you are responsible for ensuring consistency.
In particular,
you are responsible for controlling stack overflow.
-You can use the function lua_checkstack
-to ensure that the stack has enough space for pushing new elements.
+When you call any API function,
+you must ensure the stack has enough room to accommodate the results.
+
+
+
+There is one exception to the above rule:
+When you call a Lua function
+without a fixed number of results (see lua_call),
+Lua ensures that the stack has enough space for all results.
+However, it does not ensure any extra space.
+So, before pushing anything on the stack after such a call
+you should use lua_checkstack.
Whenever Lua calls C,
it ensures that the stack has space for
-at least LUA_MINSTACK extra slots.
+at least LUA_MINSTACK extra elements;
+that is, you can safely push up to LUA_MINSTACK values into it.
LUA_MINSTACK is defined as 20,
so that usually you do not have to worry about stack space
unless your code has loops pushing elements onto the stack.
-
-
-
-When you call a Lua function
-without a fixed number of results (see lua_call),
-Lua ensures that the stack has enough space for all results,
-but it does not ensure any extra space.
-So, before pushing anything in the stack after such a call
-you should use lua_checkstack.
+Whenever necessary,
+you can use the function lua_checkstack
+to ensure that the stack has enough space for pushing new elements.
-
Any function in the API that receives stack indices works only with valid indices or acceptable indices.
A valid index is an index that refers to a
position that stores a modifiable Lua value.
It comprises stack indices between 1 and the stack top
(1 ≤ abs(index) ≤ top)
plus pseudo-indices,
which represent some positions that are accessible to C code
but that are not in the stack.
-Pseudo-indices are used to access the registry (see §4.5)
-and the upvalues of a C function (see §4.4).
+Pseudo-indices are used to access the registry (see §4.3)
+and the upvalues of a C function (see §4.2).
Functions that do not need a specific mutable position, but only a value (e.g., query functions), can be called with acceptable indices. An acceptable index can be any valid index, but it also can be any positive index after the stack top within the space allocated for the stack, that is, indices up to the stack size. (Note that 0 is never an acceptable index.) +Indices to upvalues (see §4.2) greater than the real number +of upvalues in the current C function are also acceptable (but invalid). Except when noted otherwise, functions in the API work with acceptable indices.
Acceptable indices serve to avoid extra tests against the stack top when querying the stack. For instance, a C function can query its third argument -without the need to first check whether there is a third argument, +without the need to check whether there is a third argument, that is, without the need to check whether 3 is a valid index.
For functions that can be called with acceptable indices,
any non-valid index is treated as if it
contains a value of a virtual type LUA_TNONE,
which behaves like a nil value.
-
+Several functions in the API return pointers (const char*)
+to Lua strings in the stack.
+(See lua_pushfstring, lua_pushlstring,
+lua_pushstring, and lua_tolstring.
+See also luaL_checklstring, luaL_checkstring,
+and luaL_tolstring in the auxiliary library.)
+
+
+
+In general, +Lua's garbage collection can free or move internal memory +and then invalidate pointers to internal strings. +To allow a safe use of these pointers, +The API guarantees that any pointer to a string in a stack index +is valid while the string value at that index is not removed from the stack. +(It can be moved to another index, though.) +When the index is a pseudo-index (referring to an upvalue), +the pointer is valid while the corresponding call is active and +the corresponding upvalue is not modified. + + +
+Some functions in the debug interface
+also return pointers to strings,
+namely lua_getlocal, lua_getupvalue,
+lua_setlocal, and lua_setupvalue.
+For these functions, the pointer is guaranteed to
+be valid while the caller function is active and
+the given closure (if one was given) is in the stack.
+
+
+
+Except for these guarantees, +the garbage collector is free to invalidate +any pointer to internal strings. + + + + + + + +
When a C function is created,
it is possible to associate some values with it,
thus creating a C closure
(see lua_pushcclosure);
these values are called upvalues and are
accessible to the function whenever it is called.
Whenever a C function is called,
its upvalues are located at specific pseudo-indices.
These pseudo-indices are produced by the macro
lua_upvalueindex.
The first upvalue associated with a function is at index
lua_upvalueindex(1), and so on.
Any access to lua_upvalueindex(n),
where n is greater than the number of upvalues of the
current function
(but not greater than 256,
which is one plus the maximum number of upvalues in a closure),
produces an acceptable but invalid index.
+
+A C closure can also change the values +of its corresponding upvalues. + + -
Lua provides a registry,
a predefined table that can be used by any C code to
store whatever Lua values it needs to store.
-The registry table is always located at pseudo-index
+The registry table is always accessible at pseudo-index
LUA_REGISTRYINDEX.
Any C library can store data into this table,
but it must take care to choose keys
that are different from those used
by other libraries, to avoid collisions.
Typically, you should use as key a string containing your library name,
or a light userdata with the address of a C object in your code,
or any Lua object created by your code.
As with variable names,
string keys starting with an underscore followed by
uppercase letters are reserved for Lua.
The integer keys in the registry are used
by the reference mechanism (see luaL_ref)
and by some predefined values.
-Therefore, integer keys must not be used for other purposes.
+Therefore, integer keys in the registry
+must not be used for other purposes.
When you create a new Lua state,
its registry comes with some predefined values.
These predefined values are indexed with integer keys
defined as constants in lua.h.
The following constants are defined:
LUA_RIDX_MAINTHREAD: At this index the registry has
the main thread of the state.
(The main thread is the one created together with the state.)
LUA_RIDX_GLOBALS: At this index the registry has
the global environment.
Internally, Lua uses the C longjmp facility to handle errors.
(Lua will use exceptions if you compile it as C++;
search for LUAI_THROW in the source code for details.)
-When Lua faces any error
-(such as a memory allocation error or a type error)
+When Lua faces any error,
+such as a memory allocation error or a type error,
it raises an error;
that is, it does a long jump.
A protected environment uses setjmp
to set a recovery point;
any error jumps to the most recent active recovery point.
-Inside a C function you can raise an error by calling lua_error.
+Inside a C function you can raise an error explicitly
+by calling lua_error.
Most functions in the API can raise an error, for instance due to a memory allocation error. The documentation for each function indicates whether it can raise errors.
If an error happens outside any protected environment,
Lua calls a panic function (see lua_atpanic)
and then calls abort,
thus exiting the host application.
Your panic function can avoid this exit by
never returning
(e.g., doing a long jump to your own recovery point outside Lua).
The panic function,
as its name implies,
is a mechanism of last resort.
Programs should avoid it.
As a general rule,
when a C function is called by Lua with a Lua state,
it can do whatever it wants on that Lua state,
as it should be already protected.
However,
when C code operates on other Lua states
-(e.g., a Lua argument to the function,
+(e.g., a Lua-state argument to the function,
a Lua state stored in the registry, or
the result of lua_newthread),
it should use them only in API calls that cannot raise errors.
The panic function runs as if it were a message handler (see §2.3); -in particular, the error object is at the top of the stack. +in particular, the error object is on the top of the stack. However, there is no guarantee about stack space. To push anything on the stack, -the panic function must first check the available space (see §4.2). +the panic function must first check the available space (see §4.1.1). + + + + + +
+Several functions that report errors in the API use the following +status codes to indicate different kinds of errors or other conditions: + +
LUA_OK (0): no errors.LUA_ERRRUN: a runtime error.LUA_ERRMEM:
+memory allocation error.
+For such errors, Lua does not call the message handler.
+LUA_ERRERR: error while running the message handler.LUA_ERRSYNTAX: syntax error during precompilation.LUA_YIELD: the thread (coroutine) yields.LUA_ERRFILE: a file-related error;
+e.g., it cannot open or read the file.
+These constants are defined in the header file lua.h.
-
Internally, Lua uses the C longjmp facility to yield a coroutine.
Therefore, if a C function foo calls an API function
and this API function yields
(directly or indirectly by calling another function that yields),
Lua cannot return to foo any more,
-because the longjmp removes its frame from the C stack.
+because the longjmp removes its frame from the C stack.
To avoid this kind of problem,
Lua raises an error whenever it tries to yield across an API call,
except for three functions:
lua_yieldk, lua_callk, and lua_pcallk.
All those functions receive a continuation function
(as a parameter named k) to continue execution after a yield.
We need to set some terminology to explain continuations.
We have a C function called from Lua which we will call
the original function.
This original function then calls one of those three functions in the C API,
which we will call the callee function,
that then yields the current thread.
-(This can happen when the callee function is lua_yieldk,
+This can happen when the callee function is lua_yieldk,
or when the callee function is either lua_callk or lua_pcallk
-and the function called by them yields.)
+and the function called by them yields.
Suppose the running thread yields while executing the callee function. After the thread resumes, it eventually will finish running the callee function. However, the callee function cannot return to the original function, -because its frame in the C stack was destroyed by the yield. +because its frame in the C stack was destroyed by the yield. Instead, Lua calls a continuation function, which was given as an argument to the callee function. As the name implies, the continuation function should continue the task of the original function.
As an illustration, consider the following function:
int original_function (lua_State *L) {
... /* code 1 */
status = lua_pcall(L, n, m, h); /* calls Lua */
... /* code 2 */
}
Now we want to allow
the Lua code being run by lua_pcall to yield.
First, we can rewrite our function like here:
int k (lua_State *L, int status, lua_KContext ctx) {
... /* code 2 */
}
int original_function (lua_State *L) {
... /* code 1 */
return k(L, lua_pcall(L, n, m, h), ctx);
}
In the above code,
the new function k is a
continuation function (with type lua_KFunction),
which should do all the work that the original function
was doing after calling lua_pcall.
Now, we must inform Lua that it must call k if the Lua code
being executed by lua_pcall gets interrupted in some way
(errors or yielding),
so we rewrite the code as here,
replacing lua_pcall by lua_pcallk:
int original_function (lua_State *L) {
... /* code 1 */
return k(L, lua_pcallk(L, n, m, h, ctx2, k), ctx1);
}
Note the external, explicit call to the continuation:
Lua will call the continuation only if needed, that is,
in case of errors or resuming after a yield.
If the called function returns normally without ever yielding,
lua_pcallk (and lua_callk) will also return normally.
(Of course, instead of calling the continuation in that case,
you can do the equivalent work directly inside the original function.)
Besides the Lua state,
the continuation function has two other parameters:
-the final status of the call plus the context value (ctx) that
+the final status of the call and the context value (ctx) that
was passed originally to lua_pcallk.
-(Lua does not use this context value;
+Lua does not use this context value;
it only passes this value from the original function to the
-continuation function.)
+continuation function.
For lua_pcallk,
the status is the same value that would be returned by lua_pcallk,
except that it is LUA_YIELD when being executed after a yield
(instead of LUA_OK).
For lua_yieldk and lua_callk,
the status is always LUA_YIELD when Lua calls the continuation.
(For these two functions,
Lua will not call the continuation in case of errors,
because they do not handle errors.)
Similarly, when using lua_callk,
you should call the continuation function
with LUA_OK as the status.
(For lua_yieldk, there is not much point in calling
directly the continuation function,
because lua_yieldk usually does not return.)
Lua treats the continuation function as if it were the original function.
The continuation function receives the same Lua stack
from the original function,
in the same state it would be if the callee function had returned.
(For instance,
after a lua_callk the function and its arguments are
removed from the stack and replaced by the results from the call.)
It also has the same upvalues.
Whatever it returns is handled by Lua as if it were the return
of the original function.
-
Here we list all functions and types from the C API in alphabetical order. Each function has an indicator like this: [-o, +p, x]
The first field, o,
is how many elements the function pops from the stack.
The second field, p,
is how many elements the function pushes onto the stack.
(Any function always pushes its results after popping its arguments.)
A field in the form x|y means the function can push (or pop)
x or y elements,
depending on the situation;
an interrogation mark '?' means that
we cannot know how many elements the function pops/pushes
-by looking only at its arguments
-(e.g., they may depend on what is on the stack).
+by looking only at its arguments.
+(For instance, they may depend on what is in the stack.)
The third field, x,
tells whether the function may raise errors:
'-' means the function never raises any error;
-'m' means the function may raise out-of-memory errors
-and errors running a __gc metamethod;
-'e' means the function may raise any errors
-(it can run arbitrary Lua code,
-either directly or through metamethods);
-'v' means the function may raise an error on purpose.
+'m' means the function may raise only out-of-memory errors;
+'v' means the function may raise the errors explained in the text;
+'e' means the function can run arbitrary Lua code,
+either directly or through metamethods,
+and therefore may raise any errors.
lua_absindex[-0, +0, –]
int lua_absindex (lua_State *L, int idx);
Converts the acceptable index idx
into an equivalent absolute index
-(that is, one that does not depend on the stack top).
+(that is, one that does not depend on the stack size).
lua_Alloctypedef void * (*lua_Alloc) (void *ud,
void *ptr,
size_t osize,
size_t nsize);
The type of the memory-allocation function used by Lua states.
The allocator function must provide a
functionality similar to realloc,
but not exactly the same.
Its arguments are
ud, an opaque pointer passed to lua_newstate;
ptr, a pointer to the block being allocated/reallocated/freed;
osize, the original size of the block or some code about what
is being allocated;
and nsize, the new size of the block.
When ptr is not NULL,
osize is the size of the block pointed by ptr,
that is, the size given when it was allocated or reallocated.
When ptr is NULL,
osize encodes the kind of object that Lua is allocating.
osize is any of
LUA_TSTRING, LUA_TTABLE, LUA_TFUNCTION,
LUA_TUSERDATA, or LUA_TTHREAD when (and only when)
Lua is creating a new object of that type.
When osize is some other value,
Lua is allocating memory for something else.
Lua assumes the following behavior from the allocator function:
When nsize is zero,
the allocator must behave like free
-and return NULL.
+and then return NULL.
When nsize is not zero,
the allocator must behave like realloc.
-The allocator returns NULL
+In particular, the allocator returns NULL
if and only if it cannot fulfill the request.
-Lua assumes that the allocator never fails when
-osize >= nsize.
Here is a simple implementation for the allocator function.
It is used in the auxiliary library by luaL_newstate.
static void *l_alloc (void *ud, void *ptr, size_t osize,
size_t nsize) {
(void)ud; (void)osize; /* not used */
if (nsize == 0) {
free(ptr);
return NULL;
}
else
return realloc(ptr, nsize);
}
Note that Standard C ensures
that free(NULL) has no effect and that
realloc(NULL,size) is equivalent to malloc(size).
-This code assumes that realloc does not fail when shrinking a block.
-(Although Standard C does not ensure this behavior,
-it seems to be a safe assumption.)
lua_arith[-(2|1), +1, e]
void lua_arith (lua_State *L, int op);
Performs an arithmetic or bitwise operation over the two values (or one, in the case of negations) at the top of the stack, -with the value at the top being the second operand, +with the value on the top being the second operand, pops these values, and pushes the result of the operation. The function follows the semantics of the corresponding Lua operator (that is, it may call metamethods).
The value of op must be one of the following constants:
LUA_OPADD: performs addition (+)LUA_OPSUB: performs subtraction (-)LUA_OPMUL: performs multiplication (*)LUA_OPDIV: performs float division (/)LUA_OPIDIV: performs floor division (//)LUA_OPMOD: performs modulo (%)LUA_OPPOW: performs exponentiation (^)LUA_OPUNM: performs mathematical negation (unary -)LUA_OPBNOT: performs bitwise NOT (~)LUA_OPBAND: performs bitwise AND (&)LUA_OPBOR: performs bitwise OR (|)LUA_OPBXOR: performs bitwise exclusive OR (~)LUA_OPSHL: performs left shift (<<)LUA_OPSHR: performs right shift (>>)lua_atpanic[-0, +0, –]
lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);
-Sets a new panic function and returns the old one (see §4.6). +Sets a new panic function and returns the old one (see §4.4).
lua_call[-(nargs+1), +nresults, e]
void lua_call (lua_State *L, int nargs, int nresults);
Calls a function.
+Like regular Lua calls,
+lua_call respects the __call metamethod.
+So, here the word "function"
+means any callable value.
-To call a function you must use the following protocol:
+To do a call you must use the following protocol:
first, the function to be called is pushed onto the stack;
-then, the arguments to the function are pushed
+then, the arguments to the call are pushed
in direct order;
that is, the first argument is pushed first.
Finally you call lua_call;
nargs is the number of arguments that you pushed onto the stack.
-All arguments and the function value are popped from the stack
-when the function is called.
-The function results are pushed onto the stack when the function returns.
+When the function returns,
+all arguments and the function value are popped
+and the call results are pushed onto the stack.
The number of results is adjusted to nresults,
unless nresults is LUA_MULTRET.
In this case, all results from the function are pushed;
Lua takes care that the returned values fit into the stack space,
but it does not ensure any extra space in the stack.
The function results are pushed onto the stack in direct order
(the first result is pushed first),
so that after the call the last result is on the top of the stack.
-Any error inside the called function is propagated upwards
+Any error while calling and running the function is propagated upwards
(with a longjmp).
The following example shows how the host program can do the equivalent to this Lua code:
a = f("how", t.x, 14)
Here it is in C:
lua_getglobal(L, "f"); /* function to be called */
lua_pushliteral(L, "how"); /* 1st argument */
lua_getglobal(L, "t"); /* table to be indexed */
lua_getfield(L, -1, "x"); /* push result of t.x (2nd arg) */
lua_remove(L, -2); /* remove 't' from the stack */
lua_pushinteger(L, 14); /* 3rd argument */
lua_call(L, 3, 1); /* call 'f' with 3 arguments and 1 result */
lua_setglobal(L, "a"); /* set global 'a' */
Note that the code above is balanced: at its end, the stack is back to its original configuration. This is considered good programming practice.
lua_callk[-(nargs + 1), +nresults, e]
void lua_callk (lua_State *L,
int nargs,
int nresults,
lua_KContext ctx,
lua_KFunction k);
This function behaves exactly like lua_call,
-but allows the called function to yield (see §4.7).
+but allows the called function to yield (see §4.5).
lua_CFunctiontypedef int (*lua_CFunction) (lua_State *L);
Type for C functions.
In order to communicate properly with Lua,
a C function must use the following protocol,
which defines the way parameters and results are passed:
a C function receives its arguments from Lua in its stack
in direct order (the first argument is pushed first).
So, when the function starts,
lua_gettop(L) returns the number of arguments received by the function.
The first argument (if any) is at index 1
and its last argument is at index lua_gettop(L).
To return values to Lua, a C function just pushes them onto the stack,
in direct order (the first result is pushed first),
-and returns the number of results.
+and returns in C the number of results.
Any other value in the stack below the results will be properly
discarded by Lua.
Like a Lua function, a C function called by Lua can also return
many results.
As an example, the following function receives a variable number of numeric arguments and returns their average and their sum:
static int foo (lua_State *L) {
int n = lua_gettop(L); /* number of arguments */
lua_Number sum = 0.0;
int i;
for (i = 1; i <= n; i++) {
if (!lua_isnumber(L, i)) {
lua_pushliteral(L, "incorrect argument");
lua_error(L);
}
sum += lua_tonumber(L, i);
}
lua_pushnumber(L, sum/n); /* first result */
lua_pushnumber(L, sum); /* second result */
return 2; /* number of results */
}
lua_checkstack[-0, +0, –]
int lua_checkstack (lua_State *L, int n);
-Ensures that the stack has space for at least n extra slots
-(that is, that you can safely push up to n values into it).
+Ensures that the stack has space for at least n extra elements,
+that is, that you can safely push up to n values into it.
It returns false if it cannot fulfill the request,
either because it would cause the stack
-to be larger than a fixed maximum size
+to be greater than a fixed maximum size
(typically at least several thousand elements) or
because it cannot allocate memory for the extra space.
This function never shrinks the stack;
-if the stack already has space for the extra slots,
+if the stack already has space for the extra elements,
it is left unchanged.
lua_close[-0, +0, –]
void lua_close (lua_State *L);
-Destroys all objects in the given Lua state -(calling the corresponding garbage-collection metamethods, if any) +Close all active to-be-closed variables in the main thread, +release all objects in the given Lua state +(calling the corresponding garbage-collection metamethods, if any), and frees all dynamic memory used by this state. -In several platforms, you may not need to call this function, + + +
+On several platforms, you may not need to call this function, because all resources are naturally released when the host program ends. On the other hand, long-running programs that create multiple states, such as daemons or web servers, will probably need to close states as soon as they are not needed.
lua_compare[-0, +0, e]
int lua_compare (lua_State *L, int index1, int index2, int op);
Compares two Lua values.
Returns 1 if the value at index index1 satisfies op
when compared with the value at index index2,
following the semantics of the corresponding Lua operator
(that is, it may call metamethods).
Otherwise returns 0.
Also returns 0 if any of the indices is not valid.
The value of op must be one of the following constants:
LUA_OPEQ: compares for equality (==)LUA_OPLT: compares for less than (<)LUA_OPLE: compares for less or equal (<=)lua_concat[-n, +1, e]
void lua_concat (lua_State *L, int n);
Concatenates the n values at the top of the stack,
-pops them, and leaves the result at the top.
+pops them, and leaves the result on the top.
If n is 1, the result is the single value on the stack
(that is, the function does nothing);
if n is 0, the result is the empty string.
Concatenation is performed following the usual semantics of Lua
(see §3.4.6).
lua_copy[-0, +0, –]
void lua_copy (lua_State *L, int fromidx, int toidx);
Copies the element at index fromidx
into the valid index toidx,
replacing the value at that position.
Values at other positions are not affected.
lua_createtable[-0, +1, m]
void lua_createtable (lua_State *L, int narr, int nrec);
Creates a new empty table and pushes it onto the stack.
Parameter narr is a hint for how many elements the table
will have as a sequence;
parameter nrec is a hint for how many other elements
the table will have.
Lua may use these hints to preallocate memory for the new table.
-This preallocation is useful for performance when you know in advance
+This preallocation may help performance when you know in advance
how many elements the table will have.
Otherwise you can use the function lua_newtable.
lua_dump[-0, +0, –]
int lua_dump (lua_State *L,
lua_Writer writer,
void *data,
int strip);
Dumps a function as a binary chunk.
Receives a Lua function on the top of the stack
and produces a binary chunk that,
if loaded again,
results in a function equivalent to the one dumped.
As it produces parts of the chunk,
lua_dump calls function writer (see lua_Writer)
with the given data
to write them.
If strip is true,
the binary representation may not include all debug information
about the function,
to save space.
The value returned is the error code returned by the last call to the writer; 0 means no errors.
This function does not pop the Lua function from the stack.
lua_error[-1, +0, v]
int lua_error (lua_State *L);
-Generates a Lua error,
-using the value at the top of the stack as the error object.
+Raises a Lua error,
+using the value on the top of the stack as the error object.
This function does a long jump,
and therefore never returns
(see luaL_error).
lua_gc-[-0, +0, m] -
int lua_gc (lua_State *L, int what, int data);+[-0, +0, –] +
int lua_gc (lua_State *L, int what, ...);
Controls the garbage collector.
This function performs several tasks,
-according to the value of the parameter what:
+according to the value of the parameter what.
+For options that need extra arguments,
+they are listed after the option.
LUA_GCSTOP:
-stops the garbage collector.
+LUA_GCCOLLECT:
+Performs a full garbage-collection cycle.
LUA_GCRESTART:
-restarts the garbage collector.
+LUA_GCSTOP:
+Stops the garbage collector.
LUA_GCCOLLECT:
-performs a full garbage-collection cycle.
+LUA_GCRESTART:
+Restarts the garbage collector.
LUA_GCCOUNT:
-returns the current amount of memory (in Kbytes) in use by Lua.
+Returns the current amount of memory (in Kbytes) in use by Lua.
LUA_GCCOUNTB:
-returns the remainder of dividing the current amount of bytes of
+Returns the remainder of dividing the current amount of bytes of
memory in use by Lua by 1024.
LUA_GCSTEP:
-performs an incremental step of garbage collection.
+LUA_GCSTEP (int stepsize):
+Performs an incremental step of garbage collection,
+corresponding to the allocation of stepsize Kbytes.
LUA_GCSETPAUSE:
-sets data as the new value
-for the pause of the collector (see §2.5)
-and returns the previous value of the pause.
+LUA_GCISRUNNING:
+Returns a boolean that tells whether the collector is running
+(i.e., not stopped).
LUA_GCSETSTEPMUL:
-sets data as the new value for the step multiplier of
-the collector (see §2.5)
-and returns the previous value of the step multiplier.
+LUA_GCINC (int pause, int stepmul, stepsize):
+Changes the collector to incremental mode
+with the given parameters (see §2.5.1).
+Returns the previous mode (LUA_GCGEN or LUA_GCINC).
LUA_GCISRUNNING:
-returns a boolean that tells whether the collector is running
-(i.e., not stopped).
+LUA_GCGEN (int minormul, int majormul):
+Changes the collector to generational mode
+with the given parameters (see §2.5.2).
+Returns the previous mode (LUA_GCGEN or LUA_GCINC).
+
For more details about these options,
see collectgarbage.
lua_getallocf[-0, +0, –]
lua_Alloc lua_getallocf (lua_State *L, void **ud);
Returns the memory-allocation function of a given state.
If ud is not NULL, Lua stores in *ud the
opaque pointer given when the memory-allocator function was set.
lua_getfield[-0, +1, e]
int lua_getfield (lua_State *L, int index, const char *k);
Pushes onto the stack the value t[k],
where t is the value at the given index.
As in Lua, this function may trigger a metamethod
for the "index" event (see §2.4).
Returns the type of the pushed value.
lua_getextraspace[-0, +0, –]
void *lua_getextraspace (lua_State *L);
Returns a pointer to a raw memory area associated with the given Lua state. The application can use this area for any purpose; Lua does not use it for anything.
Each new thread has this area initialized with a copy of the area of the main thread.
By default, this area has the size of a pointer to void,
but you can recompile Lua with a different size for this area.
(See LUA_EXTRASPACE in luaconf.h.)
lua_getglobal[-0, +1, e]
int lua_getglobal (lua_State *L, const char *name);
Pushes onto the stack the value of the global name.
Returns the type of that value.
lua_geti[-0, +1, e]
int lua_geti (lua_State *L, int index, lua_Integer i);
Pushes onto the stack the value t[i],
where t is the value at the given index.
As in Lua, this function may trigger a metamethod
for the "index" event (see §2.4).
Returns the type of the pushed value.
lua_getmetatable[-0, +(0|1), –]
int lua_getmetatable (lua_State *L, int index);
If the value at the given index has a metatable, the function pushes that metatable onto the stack and returns 1. Otherwise, the function returns 0 and pushes nothing on the stack.
lua_gettable[-1, +1, e]
int lua_gettable (lua_State *L, int index);
Pushes onto the stack the value t[k],
where t is the value at the given index
-and k is the value at the top of the stack.
+and k is the value on the top of the stack.
This function pops the key from the stack, pushing the resulting value in its place. As in Lua, this function may trigger a metamethod for the "index" event (see §2.4).
Returns the type of the pushed value.
lua_gettop[-0, +0, –]
int lua_gettop (lua_State *L);
Returns the index of the top element in the stack. Because indices start at 1, this result is equal to the number of elements in the stack; in particular, 0 means an empty stack. -
lua_getuservalue+
lua_getiuservalue[-0, +1, –] -
int lua_getuservalue (lua_State *L, int index);+
int lua_getiuservalue (lua_State *L, int index, int n);
-Pushes onto the stack the Lua value associated with the full userdata
-at the given index.
+Pushes onto the stack the n-th user value associated with the
+full userdata at the given index and
+returns the type of the pushed value.
-Returns the type of the pushed value.
+If the userdata does not have that value,
+pushes nil and returns LUA_TNONE.
lua_insert[-1, +1, –]
void lua_insert (lua_State *L, int index);
Moves the top element into the given valid index, shifting up the elements above this index to open space. This function cannot be called with a pseudo-index, because a pseudo-index is not an actual stack position.
lua_Integertypedef ... lua_Integer;
The type of integers in Lua.
By default this type is long long,
(usually a 64-bit two-complement integer),
but that can be changed to long or int
(usually a 32-bit two-complement integer).
(See LUA_INT_TYPE in luaconf.h.)
Lua also defines the constants
LUA_MININTEGER and LUA_MAXINTEGER,
with the minimum and the maximum values that fit in this type.
lua_isboolean[-0, +0, –]
int lua_isboolean (lua_State *L, int index);
Returns 1 if the value at the given index is a boolean, and 0 otherwise.
lua_iscfunction[-0, +0, –]
int lua_iscfunction (lua_State *L, int index);
Returns 1 if the value at the given index is a C function, and 0 otherwise.
lua_isfunction[-0, +0, –]
int lua_isfunction (lua_State *L, int index);
Returns 1 if the value at the given index is a function (either C or Lua), and 0 otherwise.
lua_isinteger[-0, +0, –]
int lua_isinteger (lua_State *L, int index);
Returns 1 if the value at the given index is an integer (that is, the value is a number and is represented as an integer), and 0 otherwise.
lua_islightuserdata[-0, +0, –]
int lua_islightuserdata (lua_State *L, int index);
Returns 1 if the value at the given index is a light userdata, and 0 otherwise.
lua_isnil[-0, +0, –]
int lua_isnil (lua_State *L, int index);
Returns 1 if the value at the given index is nil, and 0 otherwise.
lua_isnone[-0, +0, –]
int lua_isnone (lua_State *L, int index);
Returns 1 if the given index is not valid, and 0 otherwise.
lua_isnoneornil[-0, +0, –]
int lua_isnoneornil (lua_State *L, int index);
Returns 1 if the given index is not valid or if the value at this index is nil, and 0 otherwise.
lua_isnumber[-0, +0, –]
int lua_isnumber (lua_State *L, int index);
Returns 1 if the value at the given index is a number or a string convertible to a number, and 0 otherwise.
lua_isstring[-0, +0, –]
int lua_isstring (lua_State *L, int index);
Returns 1 if the value at the given index is a string or a number (which is always convertible to a string), and 0 otherwise.
lua_istable[-0, +0, –]
int lua_istable (lua_State *L, int index);
Returns 1 if the value at the given index is a table, and 0 otherwise.
lua_isthread[-0, +0, –]
int lua_isthread (lua_State *L, int index);
Returns 1 if the value at the given index is a thread, and 0 otherwise.
lua_isuserdata[-0, +0, –]
int lua_isuserdata (lua_State *L, int index);
Returns 1 if the value at the given index is a userdata (either full or light), and 0 otherwise.
lua_isyieldable[-0, +0, –]
int lua_isyieldable (lua_State *L);
Returns 1 if the given coroutine can yield, and 0 otherwise.
lua_KContexttypedef ... lua_KContext;
The type for continuation-function contexts.
It must be a numeric type.
This type is defined as intptr_t
when intptr_t is available,
so that it can store pointers too.
Otherwise, it is defined as ptrdiff_t.
lua_KFunctiontypedef int (*lua_KFunction) (lua_State *L, int status, lua_KContext ctx);
-Type for continuation functions (see §4.7). +Type for continuation functions (see §4.5).
lua_len[-0, +1, e]
void lua_len (lua_State *L, int index);
Returns the length of the value at the given index.
It is equivalent to the '#' operator in Lua (see §3.4.7) and
may trigger a metamethod for the "length" event (see §2.4).
The result is pushed on the stack.
lua_load[-0, +1, –]
int lua_load (lua_State *L,
lua_Reader reader,
void *data,
const char *chunkname,
const char *mode);
Loads a Lua chunk without running it.
If there are no errors,
lua_load pushes the compiled chunk as a Lua
function on top of the stack.
Otherwise, it pushes an error message.
-
-The return values of lua_load are:
-
-
LUA_OK: no errors;LUA_ERRSYNTAX:
-syntax error during precompilation;LUA_ERRMEM:
-memory allocation (out-of-memory) error;LUA_ERRGCMM:
-error while running a __gc metamethod.
-(This error has no relation with the chunk being loaded.
-It is generated by the garbage collector.)
-
The lua_load function uses a user-supplied reader function
to read the chunk (see lua_Reader).
The data argument is an opaque value passed to the reader function.
The chunkname argument gives a name to the chunk,
-which is used for error messages and in debug information (see §4.9).
+which is used for error messages and in debug information (see §4.7).
lua_load automatically detects whether the chunk is text or binary
and loads it accordingly (see program luac).
The string mode works as in function load,
with the addition that
a NULL value is equivalent to the string "bt".
lua_load uses the stack internally,
so the reader function must always leave the stack
unmodified when returning.
+
+lua_load can return
+LUA_OK, LUA_ERRSYNTAX, or LUA_ERRMEM.
+The function may also return other values corresponding to
+errors raised by the read function (see §4.4.1).
+
+
If the resulting function has upvalues,
its first upvalue is set to the value of the global environment
-stored at index LUA_RIDX_GLOBALS in the registry (see §4.5).
+stored at index LUA_RIDX_GLOBALS in the registry (see §4.3).
When loading main chunks,
this upvalue will be the _ENV variable (see §2.2).
Other upvalues are initialized with nil.
lua_newstate[-0, +0, –]
lua_State *lua_newstate (lua_Alloc f, void *ud);
-Creates a new thread running in a new, independent state.
-Returns NULL if it cannot create the thread or the state
+Creates a new independent state and returns its main thread.
+Returns NULL if it cannot create the state
(due to lack of memory).
The argument f is the allocator function;
-Lua does all memory allocation for this state
+Lua will do all memory allocation for this state
through this function (see lua_Alloc).
The second argument, ud, is an opaque pointer that Lua
passes to the allocator in every call.
lua_newtable[-0, +1, m]
void lua_newtable (lua_State *L);
Creates a new empty table and pushes it onto the stack.
It is equivalent to lua_createtable(L, 0, 0).
lua_newthread[-0, +1, m]
lua_State *lua_newthread (lua_State *L);
Creates a new thread, pushes it on the stack,
and returns a pointer to a lua_State that represents this new thread.
The new thread returned by this function shares with the original thread
its global environment,
but has an independent execution stack.
-There is no explicit function to close or to destroy a thread. Threads are subject to garbage collection, like any Lua object. -
lua_newuserdata+
lua_newuserdatauv[-0, +1, m] -
void *lua_newuserdata (lua_State *L, size_t size);+
void *lua_newuserdatauv (lua_State *L, size_t size, int nuvalue);
-This function allocates a new block of memory with the given size,
-pushes onto the stack a new full userdata with the block address,
-and returns this address.
-The host program can freely use this memory.
+This function creates and pushes on the stack a new full userdata,
+with nuvalue associated Lua values, called user values,
+plus an associated block of raw memory with size bytes.
+(The user values can be set and read with the functions
+lua_setiuservalue and lua_getiuservalue.)
+
+
+
+The function returns the address of the block of memory. +Lua ensures that this address is valid as long as +the corresponding userdata is alive (see §2.5). +Moreover, if the userdata is marked for finalization (see §2.5.3), +its address is valid at least until the call to its finalizer.
lua_next-[-1, +(2|0), e] +[-1, +(2|0), v]
int lua_next (lua_State *L, int index);
Pops a key from the stack,
-and pushes a key–value pair from the table at the given index
-(the "next" pair after the given key).
+and pushes a key–value pair from the table at the given index,
+the "next" pair after the given key.
If there are no more elements in the table,
-then lua_next returns 0 (and pushes nothing).
+then lua_next returns 0 and pushes nothing.
-A typical traversal looks like this: +A typical table traversal looks like this:
/* table is in the stack at index 't' */
lua_pushnil(L); /* first key */
while (lua_next(L, t) != 0) {
/* uses 'key' (at index -2) and 'value' (at index -1) */
printf("%s - %s\n",
lua_typename(L, lua_type(L, -2)),
lua_typename(L, lua_type(L, -1)));
/* removes 'value'; keeps 'key' for next iteration */
lua_pop(L, 1);
}
While traversing a table,
-do not call lua_tolstring directly on a key,
+avoid calling lua_tolstring directly on a key,
unless you know that the key is actually a string.
Recall that lua_tolstring may change
the value at the given index;
this confuses the next call to lua_next.
+This function may raise an error if the given key
+is neither nil nor present in the table.
See function next for the caveats of modifying
the table during its traversal.
lua_Numbertypedef ... lua_Number;
The type of floats in Lua.
By default this type is double,
but that can be changed to a single float or a long double.
(See LUA_FLOAT_TYPE in luaconf.h.)
lua_numbertointegerint lua_numbertointeger (lua_Number n, lua_Integer *p);
-Converts a Lua float to a Lua integer.
-This macro assumes that n has an integral value.
+Tries to convert a Lua float to a Lua integer;
+the float n must have an integral value.
If that value is within the range of Lua integers,
it is converted to an integer and assigned to *p.
The macro results in a boolean indicating whether the
conversion was successful.
(Note that this range test can be tricky to do
-correctly without this macro,
-due to roundings.)
+correctly without this macro, due to rounding.)
This macro may evaluate its arguments more than once.
lua_pcall[-(nargs + 1), +(nresults|1), –]
int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);
-Calls a function in protected mode. +Calls a function (or a callable object) in protected mode.
Both nargs and nresults have the same meaning as
in lua_call.
If there are no errors during the call,
lua_pcall behaves exactly like lua_call.
However, if there is any error,
lua_pcall catches it,
pushes a single value on the stack (the error object),
and returns an error code.
Like lua_call,
lua_pcall always removes the function
and its arguments from the stack.
If msgh is 0,
then the error object returned on the stack
is exactly the original error object.
Otherwise, msgh is the stack index of a
message handler.
(This index cannot be a pseudo-index.)
In case of runtime errors,
-this function will be called with the error object
+this handler will be called with the error object
and its return value will be the object
returned on the stack by lua_pcall.
Typically, the message handler is used to add more debug
information to the error object, such as a stack traceback.
Such information cannot be gathered after the return of lua_pcall,
since by then the stack has unwound.
-The lua_pcall function returns one of the following constants
-(defined in lua.h):
-
-
LUA_OK (0):
-success.LUA_ERRRUN:
-a runtime error.
-LUA_ERRMEM:
-memory allocation error.
-For such errors, Lua does not call the message handler.
-LUA_ERRERR:
-error while running the message handler.
-LUA_ERRGCMM:
-error while running a __gc metamethod.
-For such errors, Lua does not call the message handler
-(as this kind of error typically has no relation
-with the function being called).
-lua_pcall function returns one of the following status codes:
+LUA_OK, LUA_ERRRUN, LUA_ERRMEM, or LUA_ERRERR.
-lua_pcallk[-(nargs + 1), +(nresults|1), –]
int lua_pcallk (lua_State *L,
int nargs,
int nresults,
int msgh,
lua_KContext ctx,
lua_KFunction k);
This function behaves exactly like lua_pcall,
-but allows the called function to yield (see §4.7).
+except that it allows the called function to yield (see §4.5).
lua_pop-[-n, +0, –] +[-n, +0, e]
void lua_pop (lua_State *L, int n);
Pops n elements from the stack.
+
+This function can run arbitrary code when removing an index +marked as to-be-closed from the stack. + +
lua_pushboolean[-0, +1, –]
void lua_pushboolean (lua_State *L, int b);
Pushes a boolean value with value b onto the stack.
lua_pushcclosure[-n, +1, m]
void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);
Pushes a new C closure onto the stack.
+This function receives a pointer to a C function
+and pushes onto the stack a Lua value of type function that,
+when called, invokes the corresponding C function.
+The parameter n tells how many upvalues this function will have
+(see §4.2).
+
+
+
+Any function to be callable by Lua must
+follow the correct protocol to receive its parameters
+and return its results (see lua_CFunction).
When a C function is created,
it is possible to associate some values with it,
-thus creating a C closure (see §4.4);
-these values are then accessible to the function whenever it is called.
-To associate values with a C function,
-first these values must be pushed onto the stack
-(when there are multiple values, the first value is pushed first).
+the so called upvalues;
+these upvalues are then accessible to the function whenever it is called.
+This association is called a C closure (see §4.2).
+To create a C closure,
+first the initial values for its upvalues must be pushed onto the stack.
+(When there are multiple upvalues, the first value is pushed first.)
Then lua_pushcclosure
is called to create and push the C function onto the stack,
with the argument n telling how many values will be
associated with the function.
lua_pushcclosure also pops these values from the stack.
The maximum value for n is 255.
When n is zero,
this function creates a light C function,
which is just a pointer to the C function.
In that case, it never raises a memory error.
lua_pushcfunction[-0, +1, –]
void lua_pushcfunction (lua_State *L, lua_CFunction f);
Pushes a C function onto the stack.
-This function receives a pointer to a C function
-and pushes onto the stack a Lua value of type function that,
-when called, invokes the corresponding C function.
-
-
-
-Any function to be callable by Lua must
-follow the correct protocol to receive its parameters
-and return its results (see lua_CFunction).
+This function is equivalent to lua_pushcclosure with no upvalues.
lua_pushfstring-[-0, +1, e] +[-0, +1, v]
const char *lua_pushfstring (lua_State *L, const char *fmt, ...);
Pushes onto the stack a formatted string
-and returns a pointer to this string.
+and returns a pointer to this string (see §4.1.3).
It is similar to the ISO C function sprintf,
-but has some important differences:
-
-
%%' (inserts the character '%'),
'%s' (inserts a zero-terminated string, with no size restrictions),
'%f' (inserts a lua_Number),
'%I' (inserts a lua_Integer),
-'%p' (inserts a pointer as a hexadecimal numeral),
+'%p' (inserts a pointer),
'%d' (inserts an int),
'%c' (inserts an int as a one-byte character), and
'%U' (inserts a long int as a UTF-8 byte sequence).
--Unlike other push functions, -this function checks for the stack space it needs, -including the slot for its result. +This function may raise errors due to memory overflow +or an invalid conversion specifier.
lua_pushglobaltable[-0, +1, –]
void lua_pushglobaltable (lua_State *L);
Pushes the global environment onto the stack.
lua_pushinteger[-0, +1, –]
void lua_pushinteger (lua_State *L, lua_Integer n);
Pushes an integer with value n onto the stack.
lua_pushlightuserdata[-0, +1, –]
void lua_pushlightuserdata (lua_State *L, void *p);
Pushes a light userdata onto the stack.
Userdata represent C values in Lua.
A light userdata represents a pointer, a void*.
It is a value (like a number):
you do not create it, it has no individual metatable,
and it is not collected (as it was never created).
A light userdata is equal to "any"
light userdata with the same C address.
lua_pushliteral[-0, +1, m]
const char *lua_pushliteral (lua_State *L, const char *s);
This macro is equivalent to lua_pushstring,
but should be used only when s is a literal string.
+(Lua may optimize this case.)
lua_pushlstring[-0, +1, m]
const char *lua_pushlstring (lua_State *L, const char *s, size_t len);
Pushes the string pointed to by s with size len
onto the stack.
-Lua makes (or reuses) an internal copy of the given string,
+Lua will make or reuse an internal copy of the given string,
so the memory at s can be freed or reused immediately after
the function returns.
The string can contain any binary data,
including embedded zeros.
-Returns a pointer to the internal copy of the string. +Returns a pointer to the internal copy of the string (see §4.1.3).
lua_pushnil[-0, +1, –]
void lua_pushnil (lua_State *L);
Pushes a nil value onto the stack.
lua_pushnumber[-0, +1, –]
void lua_pushnumber (lua_State *L, lua_Number n);
Pushes a float with value n onto the stack.
lua_pushstring[-0, +1, m]
const char *lua_pushstring (lua_State *L, const char *s);
Pushes the zero-terminated string pointed to by s
onto the stack.
-Lua makes (or reuses) an internal copy of the given string,
+Lua will make or reuse an internal copy of the given string,
so the memory at s can be freed or reused immediately after
the function returns.
-Returns a pointer to the internal copy of the string. +Returns a pointer to the internal copy of the string (see §4.1.3).
If s is NULL, pushes nil and returns NULL.
lua_pushthread[-0, +1, –]
int lua_pushthread (lua_State *L);
Pushes the thread represented by L onto the stack.
Returns 1 if this thread is the main thread of its state.
lua_pushvalue[-0, +1, –]
void lua_pushvalue (lua_State *L, int index);
Pushes a copy of the element at the given index onto the stack.
lua_pushvfstring-[-0, +1, m] +[-0, +1, v]
const char *lua_pushvfstring (lua_State *L,
const char *fmt,
va_list argp);
Equivalent to lua_pushfstring, except that it receives a va_list
instead of a variable number of arguments.
lua_rawequal[-0, +0, –]
int lua_rawequal (lua_State *L, int index1, int index2);
Returns 1 if the two values in indices index1 and
index2 are primitively equal
-(that is, without calling the __eq metamethod).
+(that is, equal without calling the __eq metamethod).
Otherwise returns 0.
Also returns 0 if any of the indices are not valid.
lua_rawget[-1, +1, –]
int lua_rawget (lua_State *L, int index);
Similar to lua_gettable, but does a raw access
(i.e., without metamethods).
lua_rawgeti[-0, +1, –]
int lua_rawgeti (lua_State *L, int index, lua_Integer n);
Pushes onto the stack the value t[n],
where t is the table at the given index.
The access is raw,
-that is, it does not invoke the __index metamethod.
+that is, it does not use the __index metavalue.
Returns the type of the pushed value.
lua_rawgetp[-0, +1, –]
int lua_rawgetp (lua_State *L, int index, const void *p);
Pushes onto the stack the value t[k],
where t is the table at the given index and
k is the pointer p represented as a light userdata.
The access is raw;
-that is, it does not invoke the __index metamethod.
+that is, it does not use the __index metavalue.
Returns the type of the pushed value.
lua_rawlen[-0, +0, –] -
size_t lua_rawlen (lua_State *L, int index);+
lua_Unsigned lua_rawlen (lua_State *L, int index);
Returns the raw "length" of the value at the given index:
for strings, this is the string length;
for tables, this is the result of the length operator ('#')
with no metamethods;
for userdata, this is the size of the block of memory allocated
-for the userdata;
-for other values, it is 0.
+for the userdata.
+For other values, this call returns 0.
lua_rawset[-2, +0, m]
void lua_rawset (lua_State *L, int index);
Similar to lua_settable, but does a raw assignment
(i.e., without metamethods).
lua_rawseti[-1, +0, m]
void lua_rawseti (lua_State *L, int index, lua_Integer i);
Does the equivalent of t[i] = v,
where t is the table at the given index
-and v is the value at the top of the stack.
+and v is the value on the top of the stack.
This function pops the value from the stack.
The assignment is raw,
-that is, it does not invoke the __newindex metamethod.
+that is, it does not use the __newindex metavalue.
lua_rawsetp[-1, +0, m]
void lua_rawsetp (lua_State *L, int index, const void *p);
Does the equivalent of t[p] = v,
where t is the table at the given index,
p is encoded as a light userdata,
-and v is the value at the top of the stack.
+and v is the value on the top of the stack.
This function pops the value from the stack.
The assignment is raw,
-that is, it does not invoke __newindex metamethod.
+that is, it does not use the __newindex metavalue.
lua_Readertypedef const char * (*lua_Reader) (lua_State *L,
void *data,
size_t *size);
The reader function used by lua_load.
-Every time it needs another piece of the chunk,
-lua_load calls the reader,
+Every time lua_load needs another piece of the chunk,
+it calls the reader,
passing along its data parameter.
The reader must return a pointer to a block of memory
with a new piece of the chunk
and set size to the block size.
The block must exist until the reader function is called again.
To signal the end of the chunk,
the reader must return NULL or set size to zero.
The reader function may return pieces of any size greater than zero.
lua_register[-0, +0, e]
void lua_register (lua_State *L, const char *name, lua_CFunction f);
Sets the C function f as the new value of global name.
It is defined as a macro:
#define lua_register(L,n,f) \
(lua_pushcfunction(L, f), lua_setglobal(L, n))
lua_remove[-1, +0, –]
void lua_remove (lua_State *L, int index);
Removes the element at the given valid index, shifting down the elements above this index to fill the gap. This function cannot be called with a pseudo-index, because a pseudo-index is not an actual stack position.
lua_replace[-1, +0, –]
void lua_replace (lua_State *L, int index);
Moves the top element into the given valid index without shifting any element (therefore replacing the value at that given index), and then pops the top element. +
lua_resetthread+[-0, +?, –] +
int lua_resetthread (lua_State *L);+ +
+Resets a thread, cleaning its call stack and closing all pending
+to-be-closed variables.
+Returns a status code:
+LUA_OK for no errors in closing methods,
+or an error status otherwise.
+In case of error,
+leaves the error object on the top of the stack,
+
+
+
+
+
lua_resume[-?, +?, –] -
int lua_resume (lua_State *L, lua_State *from, int nargs);+
int lua_resume (lua_State *L, lua_State *from, int nargs, + int *nresults);
Starts and resumes a coroutine in the given thread L.
To start a coroutine,
-you push onto the thread stack the main function plus any arguments;
+you push the main function plus any arguments
+onto the empty stack of the thread.
then you call lua_resume,
with nargs being the number of arguments.
This call returns when the coroutine suspends or finishes its execution.
-When it returns, the stack contains all values passed to lua_yield,
-or all values returned by the body function.
+When it returns,
+*nresults is updated and
+the top of the stack contains
+the *nresults values passed to lua_yield
+or returned by the body function.
lua_resume returns
LUA_YIELD if the coroutine yields,
LUA_OK if the coroutine finishes its execution
without errors,
-or an error code in case of errors (see lua_pcall).
-
-
-
+or an error code in case of errors (see §4.4.1). In case of errors, -the stack is not unwound, -so you can use the debug API over it. -The error object is on the top of the stack. +the error object is on the top of the stack.
To resume a coroutine,
-you remove any results from the last lua_yield,
-put on its stack only the values to
-be passed as results from yield,
+you remove the *nresults yielded values from its stack,
+push the values to be passed as results from yield,
and then call lua_resume.
The parameter from represents the coroutine that is resuming L.
If there is no such coroutine,
this parameter can be NULL.
lua_rotate[-0, +0, –]
void lua_rotate (lua_State *L, int idx, int n);
Rotates the stack elements between the valid index idx
and the top of the stack.
The elements are rotated n positions in the direction of the top,
for a positive n,
or -n positions in the direction of the bottom,
for a negative n.
The absolute value of n must not be greater than the size
of the slice being rotated.
This function cannot be called with a pseudo-index,
because a pseudo-index is not an actual stack position.
lua_setallocf[-0, +0, –]
void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);
Changes the allocator function of a given state to f
with user data ud.
lua_setfield[-1, +0, e]
void lua_setfield (lua_State *L, int index, const char *k);
Does the equivalent to t[k] = v,
where t is the value at the given index
-and v is the value at the top of the stack.
+and v is the value on the top of the stack.
This function pops the value from the stack. As in Lua, this function may trigger a metamethod for the "newindex" event (see §2.4).
lua_setglobal[-1, +0, e]
void lua_setglobal (lua_State *L, const char *name);
Pops a value from the stack and
sets it as the new value of global name.
lua_seti[-1, +0, e]
void lua_seti (lua_State *L, int index, lua_Integer n);
Does the equivalent to t[n] = v,
where t is the value at the given index
-and v is the value at the top of the stack.
+and v is the value on the top of the stack.
This function pops the value from the stack. As in Lua, this function may trigger a metamethod for the "newindex" event (see §2.4). +
lua_setiuservalue+[-1, +0, –] +
int lua_setiuservalue (lua_State *L, int index, int n);+ +
+Pops a value from the stack and sets it as
+the new n-th user value associated to the
+full userdata at the given index.
+Returns 0 if the userdata does not have that value.
+
+
+
+
+
lua_setmetatable[-1, +0, –] -
void lua_setmetatable (lua_State *L, int index);+
int lua_setmetatable (lua_State *L, int index);+ +
+Pops a table or nil from the stack and +sets that value as the new metatable for the value at the given index. +(nil means no metatable.) +
-Pops a table from the stack and
-sets it as the new metatable for the value at the given index.
+(For historical reasons, this function returns an int,
+which now is always 1.)
lua_settable[-2, +0, e]
void lua_settable (lua_State *L, int index);
Does the equivalent to t[k] = v,
where t is the value at the given index,
-v is the value at the top of the stack,
+v is the value on the top of the stack,
and k is the value just below the top.
This function pops both the key and the value from the stack. As in Lua, this function may trigger a metamethod for the "newindex" event (see §2.4).
lua_settop-[-?, +?, –] +[-?, +?, e]
void lua_settop (lua_State *L, int index);
Accepts any index, or 0,
and sets the stack top to this index.
-If the new top is larger than the old one,
+If the new top is greater than the old one,
then the new elements are filled with nil.
If index is 0, then all stack elements are removed.
+
+This function can run arbitrary code when removing an index +marked as to-be-closed from the stack. -
lua_setuservalue-[-1, +0, –] -
void lua_setuservalue (lua_State *L, int index);+ + +
lua_setwarnf+[-0, +0, –] +
void lua_setwarnf (lua_State *L, lua_WarnFunction f, void *ud);
-Pops a value from the stack and sets it as
-the new value associated to the full userdata at the given index.
+Sets the warning function to be used by Lua to emit warnings
+(see lua_WarnFunction).
+The ud parameter sets the value ud passed to
+the warning function.
lua_Statetypedef struct lua_State lua_State;
An opaque structure that points to a thread and indirectly (through the thread) to the whole state of a Lua interpreter. The Lua library is fully reentrant: it has no global variables. All information about a state is accessible through this structure.
A pointer to this structure must be passed as the first argument to
every function in the library, except to lua_newstate,
which creates a Lua state from scratch.
lua_status[-0, +0, –]
int lua_status (lua_State *L);
Returns the status of the thread L.
-The status can be 0 (LUA_OK) for a normal thread,
+The status can be LUA_OK for a normal thread,
an error code if the thread finished the execution
of a lua_resume with an error,
-or LUA_YIELD if the thread is suspended.
+or LUA_YIELD if the thread is suspended.
-You can only call functions in threads with status LUA_OK.
+You can call functions only in threads with status LUA_OK.
You can resume threads with status LUA_OK
(to start a new coroutine) or LUA_YIELD
(to resume a coroutine).
lua_stringtonumber[-0, +1, –]
size_t lua_stringtonumber (lua_State *L, const char *s);
Converts the zero-terminated string s to a number,
pushes that number into the stack,
and returns the total size of the string,
that is, its length plus one.
The conversion can result in an integer or a float,
according to the lexical conventions of Lua (see §3.1).
-The string may have leading and trailing spaces and a sign.
+The string may have leading and trailing whitespaces and a sign.
If the string is not a valid numeral,
returns 0 and pushes nothing.
(Note that the result can be used as a boolean,
true if the conversion succeeds.)
lua_toboolean[-0, +0, –]
int lua_toboolean (lua_State *L, int index);
Converts the Lua value at the given index to a C boolean
value (0 or 1).
Like all tests in Lua,
lua_toboolean returns true for any Lua value
different from false and nil;
otherwise it returns false.
(If you want to accept only actual boolean values,
use lua_isboolean to test the value's type.)
lua_tocfunction[-0, +0, –]
lua_CFunction lua_tocfunction (lua_State *L, int index);
Converts a value at the given index to a C function.
That value must be a C function;
otherwise, returns NULL.
+
lua_toclose+[-0, +0, m] +
void lua_toclose (lua_State *L, int index);+ +
+Marks the given index in the stack as a
+to-be-closed "variable" (see §3.3.8).
+Like a to-be-closed variable in Lua,
+the value at that index in the stack will be closed
+when it goes out of scope.
+Here, in the context of a C function,
+to go out of scope means that the running function returns to Lua,
+there is an error,
+or the index is removed from the stack through
+lua_settop or lua_pop.
+An index marked as to-be-closed should not be removed from the stack
+by any other function in the API except lua_settop or lua_pop.
+
+
+
+This function should not be called for an index +that is equal to or below an active to-be-closed index. + + +
+In the case of an out-of-memory error, +the value in the given index is immediately closed, +as if it was already marked. + + +
+Note that, both in case of errors and of a regular return,
+by the time the __close metamethod runs,
+the C stack was already unwound,
+so that any automatic C variable declared in the calling function
+will be out of scope.
+
+
+
+
+
lua_tointeger[-0, +0, –]
lua_Integer lua_tointeger (lua_State *L, int index);
Equivalent to lua_tointegerx with isnum equal to NULL.
lua_tointegerx[-0, +0, –]
lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);
Converts the Lua value at the given index
to the signed integral type lua_Integer.
The Lua value must be an integer,
or a number or string convertible to an integer (see §3.4.3);
otherwise, lua_tointegerx returns 0.
If isnum is not NULL,
its referent is assigned a boolean value that
indicates whether the operation succeeded.
lua_tolstring[-0, +0, m]
const char *lua_tolstring (lua_State *L, int index, size_t *len);
Converts the Lua value at the given index to a C string.
If len is not NULL,
it sets *len with the string length.
The Lua value must be a string or a number;
otherwise, the function returns NULL.
If the value is a number,
then lua_tolstring also
changes the actual value in the stack to a string.
(This change confuses lua_next
when lua_tolstring is applied to keys during a table traversal.)
lua_tolstring returns a pointer
-to a string inside the Lua state.
+to a string inside the Lua state (see §4.1.3).
This string always has a zero ('\0')
after its last character (as in C),
but can contain other zeros in its body.
-
-Because Lua has garbage collection,
-there is no guarantee that the pointer returned by lua_tolstring
-will be valid after the corresponding Lua value is removed from the stack.
-
-
lua_tonumber[-0, +0, –]
lua_Number lua_tonumber (lua_State *L, int index);
Equivalent to lua_tonumberx with isnum equal to NULL.
lua_tonumberx[-0, +0, –]
lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);
Converts the Lua value at the given index
to the C type lua_Number (see lua_Number).
The Lua value must be a number or a string convertible to a number
(see §3.4.3);
otherwise, lua_tonumberx returns 0.
If isnum is not NULL,
its referent is assigned a boolean value that
indicates whether the operation succeeded.
lua_topointer[-0, +0, –]
const void *lua_topointer (lua_State *L, int index);
Converts the value at the given index to a generic
C pointer (void*).
-The value can be a userdata, a table, a thread, or a function;
+The value can be a userdata, a table, a thread, a string, or a function;
otherwise, lua_topointer returns NULL.
Different objects will give different pointers.
There is no way to convert the pointer back to its original value.
Typically this function is used only for hashing and debug information.
lua_tostring[-0, +0, m]
const char *lua_tostring (lua_State *L, int index);
Equivalent to lua_tolstring with len equal to NULL.
lua_tothread[-0, +0, –]
lua_State *lua_tothread (lua_State *L, int index);
Converts the value at the given index to a Lua thread
(represented as lua_State*).
This value must be a thread;
otherwise, the function returns NULL.
lua_touserdata[-0, +0, –]
void *lua_touserdata (lua_State *L, int index);
If the value at the given index is a full userdata,
-returns its block address.
+returns its memory-block address.
If the value is a light userdata,
-returns its pointer.
+returns its value (a pointer).
Otherwise, returns NULL.
lua_type[-0, +0, –]
int lua_type (lua_State *L, int index);
Returns the type of the value in the given valid index,
-or LUA_TNONE for a non-valid (but acceptable) index.
+or LUA_TNONE for a non-valid but acceptable index.
The types returned by lua_type are coded by the following constants
defined in lua.h:
-LUA_TNIL (0),
+LUA_TNIL,
LUA_TNUMBER,
LUA_TBOOLEAN,
LUA_TSTRING,
LUA_TTABLE,
LUA_TFUNCTION,
LUA_TUSERDATA,
LUA_TTHREAD,
and
LUA_TLIGHTUSERDATA.
lua_typename[-0, +0, –]
const char *lua_typename (lua_State *L, int tp);
Returns the name of the type encoded by the value tp,
which must be one the values returned by lua_type.
lua_Unsignedtypedef ... lua_Unsigned;
The unsigned version of lua_Integer.
lua_upvalueindex[-0, +0, –]
int lua_upvalueindex (int i);
Returns the pseudo-index that represents the i-th upvalue of
-the running function (see §4.4).
+the running function (see §4.2).
+i must be in the range [1,256].
lua_version[-0, +0, –] -
const lua_Number *lua_version (lua_State *L);+
lua_Number lua_version (lua_State *L);+ +
+Returns the version number of this core. + + + + + +
lua_WarnFunctiontypedef void (*lua_WarnFunction) (void *ud, const char *msg, int tocont);+ +
+The type of warning functions, called by Lua to emit warnings.
+The first parameter is an opaque pointer
+set by lua_setwarnf.
+The second parameter is the warning message.
+The third parameter is a boolean that
+indicates whether the message is
+to be continued by the message in the next call.
+
+
+
+See warn for more details about warnings.
+
+
+
+
+
+
lua_warning+[-0, +0, –] +
void lua_warning (lua_State *L, const char *msg, int tocont);+ +
+Emits a warning with the given message.
+A message in a call with tocont true should be
+continued in another call to this function.
+
-Returns the address of the version number
-(a C static variable)
-stored in the Lua core.
-When called with a valid lua_State,
-returns the address of the version used to create that state.
-When called with NULL,
-returns the address of the version running the call.
+See warn for more details about warnings.
lua_Writertypedef int (*lua_Writer) (lua_State *L,
const void* p,
size_t sz,
void* ud);
The type of the writer function used by lua_dump.
-Every time it produces another piece of chunk,
-lua_dump calls the writer,
+Every time lua_dump produces another piece of chunk,
+it calls the writer,
passing along the buffer to be written (p),
its size (sz),
-and the data parameter supplied to lua_dump.
+and the ud parameter supplied to lua_dump.
The writer returns an error code:
0 means no errors;
any other value means an error and stops lua_dump from
calling the writer again.
lua_xmove[-?, +?, –]
void lua_xmove (lua_State *from, lua_State *to, int n);
Exchange values between different threads of the same state.
This function pops n values from the stack from,
and pushes them onto the stack to.
lua_yield-[-?, +?, e] +[-?, +?, v]
int lua_yield (lua_State *L, int nresults);
This function is equivalent to lua_yieldk,
-but it has no continuation (see §4.7).
+but it has no continuation (see §4.5).
Therefore, when the thread resumes,
it continues the function that called
the function calling lua_yield.
+To avoid surprises,
+this function should be called only in a tail call.
lua_yieldk-[-?, +?, e] +[-?, +?, v]
int lua_yieldk (lua_State *L,
int nresults,
lua_KContext ctx,
lua_KFunction k);
Yields a coroutine (thread).
When a C function calls lua_yieldk,
the running coroutine suspends its execution,
and the call to lua_resume that started this coroutine returns.
The parameter nresults is the number of values from the stack
that will be passed as results to lua_resume.
When the coroutine is resumed again,
Lua calls the given continuation function k to continue
-the execution of the C function that yielded (see §4.7).
+the execution of the C function that yielded (see §4.5).
This continuation function receives the same stack
from the previous function,
with the n results removed and
replaced by the arguments passed to lua_resume.
Moreover,
the continuation function receives the value ctx
that was passed to lua_yieldk.
Usually, this function does not return;
when the coroutine eventually resumes,
it continues executing the continuation function.
However, there is one special case,
which is when this function is called
-from inside a line or a count hook (see §4.9).
+from inside a line or a count hook (see §4.7).
In that case, lua_yieldk should be called with no continuation
(probably in the form of lua_yield) and no results,
and the hook should return immediately after the call.
Lua will yield and,
when the coroutine resumes again,
it will continue the normal execution
of the (Lua) function that triggered the hook.
This function can raise an error if it is called from a thread -with a pending C call with no continuation function, +with a pending C call with no continuation function +(what is called a C-call boundary), or it is called from a thread that is not running inside a resume -(e.g., the main thread). +(typically the main thread). -
Lua has no built-in debugging facilities. Instead, it offers a special interface by means of functions and hooks. This interface allows the construction of different kinds of debuggers, profilers, and other tools that need "inside information" from the interpreter.
lua_Debugtypedef struct lua_Debug {
int event;
const char *name; /* (n) */
const char *namewhat; /* (n) */
const char *what; /* (S) */
const char *source; /* (S) */
+ size_t srclen; /* (S) */
int currentline; /* (l) */
int linedefined; /* (S) */
int lastlinedefined; /* (S) */
unsigned char nups; /* (u) number of upvalues */
unsigned char nparams; /* (u) number of parameters */
char isvararg; /* (u) */
char istailcall; /* (t) */
+ unsigned short ftransfer; /* (r) index of first value transferred */
+ unsigned short ntransfer; /* (r) number of transferred values */
char short_src[LUA_IDSIZE]; /* (S) */
/* private part */
other fields
} lua_Debug;
A structure used to carry different pieces of
information about a function or an activation record.
lua_getstack fills only the private part
of this structure, for later use.
To fill the other fields of lua_Debug with useful information,
-call lua_getinfo.
+you must call lua_getinfo.
The fields of lua_Debug have the following meaning:
source:
-the name of the chunk that created the function.
+the source of the chunk that created the function.
If source starts with a '@',
it means that the function was defined in a file where
the file name follows the '@'.
If source starts with a '=',
-the remainder of its contents describe the source in a user-dependent manner.
+the remainder of its contents describes the source in a user-dependent manner.
Otherwise,
the function was defined in a string where
source is that string.
srclen:
+The length of the string source.
+short_src:
a "printable" version of source, to be used in error messages.
linedefined:
the line number where the definition of the function starts.
lastlinedefined:
the line number where the definition of the function ends.
what:
the string "Lua" if the function is a Lua function,
"C" if it is a C function,
"main" if it is the main part of a chunk.
currentline:
the current line where the given function is executing.
When no line information is available,
currentline is set to -1.
name:
a reasonable name for the given function.
Because functions in Lua are first-class values,
they do not have a fixed name:
some functions can be the value of multiple global variables,
while others can be stored only in a table field.
The lua_getinfo function checks how the function was
called to find a suitable name.
If it cannot find a name,
then name is set to NULL.
namewhat:
explains the name field.
The value of namewhat can be
"global", "local", "method",
"field", "upvalue", or "" (the empty string),
according to how the function was called.
(Lua uses the empty string when no other option seems to apply.)
istailcall:
true if this function invocation was called by a tail call.
In this case, the caller of this level is not in the stack.
nups:
the number of upvalues of the function.
nparams:
-the number of fixed parameters of the function
+the number of parameters of the function
(always 0 for C functions).
isvararg:
true if the function is a vararg function
(always true for C functions).
ftransfer:
+the index in the stack of the first value being "transferred",
+that is, parameters in a call or return values in a return.
+(The other values are in consecutive indices.)
+Using this index, you can access and modify these values
+through lua_getlocal and lua_setlocal.
+This field is only meaningful during a
+call hook, denoting the first parameter,
+or a return hook, denoting the first value being returned.
+(For call hooks, this value is always 1.)
+ntransfer:
+The number of values being transferred (see previous item).
+(For calls of Lua functions,
+this value is always equal to nparams.)
+lua_gethook[-0, +0, –]
lua_Hook lua_gethook (lua_State *L);
Returns the current hook function.
lua_gethookcount[-0, +0, –]
int lua_gethookcount (lua_State *L);
Returns the current hook count.
lua_gethookmask[-0, +0, –]
int lua_gethookmask (lua_State *L);
Returns the current hook mask.
lua_getinfo-[-(0|1), +(0|1|2), e] +[-(0|1), +(0|1|2), m]
int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);
Gets information about a specific function or function invocation.
To get information about a function invocation,
the parameter ar must be a valid activation record that was
filled by a previous call to lua_getstack or
given as argument to a hook (see lua_Hook).
To get information about a function, you push it onto the stack
and start the what string with the character '>'.
(In that case,
lua_getinfo pops the function from the top of the stack.)
For instance, to know in which line a function f was defined,
you can write the following code:
lua_Debug ar;
lua_getglobal(L, "f"); /* get global 'f' */
lua_getinfo(L, ">S", &ar);
printf("%d\n", ar.linedefined);
Each character in the string what
selects some fields of the structure ar to be filled or
a value to be pushed on the stack:
n': fills in the field name and namewhat;
S':
fills in the fields source, short_src,
linedefined, lastlinedefined, and what;
l': fills in the field currentline;
t': fills in the field istailcall;
u': fills in the fields
nups, nparams, and isvararg;
f':
pushes onto the stack the function that is
running at the given level;
L':
pushes onto the stack a table whose indices are the
numbers of the lines that are valid on the function.
(A valid line is a line with some associated code,
that is, a line where you can put a break point.
Non-valid lines include empty lines and comments.)
If this option is given together with option 'f',
its table is pushed after the function.
+
+
+
+This is the only option that can raise a memory error.
-This function returns 0 on error
-(for instance, an invalid option in what).
+This function returns 0 to signal an invalid option in what;
+even then the valid options are handled correctly.
lua_getlocal[-0, +(0|1), –]
const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n);
-Gets information about a local variable of -a given activation record or a given function. +Gets information about a local variable or a temporary value +of a given activation record or a given function.
In the first case,
the parameter ar must be a valid activation record that was
filled by a previous call to lua_getstack or
given as argument to a hook (see lua_Hook).
The index n selects which local variable to inspect;
see debug.getlocal for details about variable indices
and names.
lua_getlocal pushes the variable's value onto the stack
and returns its name.
In the second case, ar must be NULL and the function
-to be inspected must be at the top of the stack.
+to be inspected must be on the top of the stack.
In this case, only parameters of Lua functions are visible
(as there is no information about what variables are active)
and no values are pushed onto the stack.
Returns NULL (and pushes nothing)
when the index is greater than
the number of active local variables.
lua_getstack[-0, +0, –]
int lua_getstack (lua_State *L, int level, lua_Debug *ar);
Gets information about the interpreter runtime stack.
This function fills parts of a lua_Debug structure with
an identification of the activation record
of the function executing at a given level.
Level 0 is the current running function,
whereas level n+1 is the function that has called level n
-(except for tail calls, which do not count on the stack).
-When there are no errors, lua_getstack returns 1;
-when called with a level greater than the stack depth,
-it returns 0.
+(except for tail calls, which do not count in the stack).
+When called with a level greater than the stack depth,
+lua_getstack returns 0;
+otherwise it returns 1.
lua_getupvalue[-0, +(0|1), –]
const char *lua_getupvalue (lua_State *L, int funcindex, int n);
Gets information about the n-th upvalue
of the closure at index funcindex.
It pushes the upvalue's value onto the stack
and returns its name.
Returns NULL (and pushes nothing)
when the index n is greater than the number of upvalues.
-For C functions, this function uses the empty string ""
-as a name for all upvalues.
-(For Lua functions,
-upvalues are the external local variables that the function uses,
-and that are consequently included in its closure.)
-
-
-
-Upvalues have no particular order,
-as they are active through the whole function.
-They are numbered in an arbitrary order.
+See debug.getupvalue for more information about upvalues.
lua_Hooktypedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);
Type for debugging hook functions.
Whenever a hook is called, its ar argument has its field
event set to the specific event that triggered the hook.
Lua identifies these events with the following constants:
LUA_HOOKCALL, LUA_HOOKRET,
LUA_HOOKTAILCALL, LUA_HOOKLINE,
and LUA_HOOKCOUNT.
Moreover, for line events, the field currentline is also set.
To get the value of any other field in ar,
the hook must call lua_getinfo.
For call events, event can be LUA_HOOKCALL,
the normal value, or LUA_HOOKTAILCALL, for a tail call;
in this case, there will be no corresponding return event.
While Lua is running a hook, it disables other calls to hooks. Therefore, if a hook calls back Lua to execute a function or a chunk, this execution occurs without any calls to hooks.
Hook functions cannot have continuations,
that is, they cannot call lua_yieldk,
lua_pcallk, or lua_callk with a non-null k.
Hook functions can yield under the following conditions:
Only count and line events can yield;
to yield, a hook function must finish its execution
calling lua_yield with nresults equal to zero
(that is, with no values).
lua_sethook[-0, +0, –]
void lua_sethook (lua_State *L, lua_Hook f, int mask, int count);
Sets the debugging hook function.
Argument f is the hook function.
mask specifies on which events the hook will be called:
it is formed by a bitwise OR of the constants
LUA_MASKCALL,
LUA_MASKRET,
LUA_MASKLINE,
and LUA_MASKCOUNT.
The count argument is only meaningful when the mask
includes LUA_MASKCOUNT.
For each event, the hook is called as explained below:
count instructions.
-(This event only happens while Lua is executing a Lua function.)
+This event only happens while Lua is executing a Lua function.
-A hook is disabled by setting mask to zero.
+Hooks are disabled by setting mask to zero.
lua_setlocal[-(0|1), +0, –]
const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n);
Sets the value of a local variable of a given activation record. -It assigns the value at the top of the stack +It assigns the value on the top of the stack to the variable and returns its name. It also pops the value from the stack.
Returns NULL (and pops nothing)
when the index is greater than
the number of active local variables.
-Parameters ar and n are as in function lua_getlocal.
+Parameters ar and n are as in the function lua_getlocal.
lua_setupvalue[-(0|1), +0, –]
const char *lua_setupvalue (lua_State *L, int funcindex, int n);
Sets the value of a closure's upvalue. -It assigns the value at the top of the stack +It assigns the value on the top of the stack to the upvalue and returns its name. It also pops the value from the stack.
Returns NULL (and pops nothing)
when the index n is greater than the number of upvalues.
-Parameters funcindex and n are as in function lua_getupvalue.
+Parameters funcindex and n are as in
+the function lua_getupvalue.
lua_upvalueid[-0, +0, –]
void *lua_upvalueid (lua_State *L, int funcindex, int n);
Returns a unique identifier for the upvalue numbered n
from the closure at index funcindex.
These unique identifiers allow a program to check whether different closures share upvalues. Lua closures that share an upvalue (that is, that access a same external local variable) will return identical ids for those upvalue indices.
-Parameters funcindex and n are as in function lua_getupvalue,
+Parameters funcindex and n are as in
+the function lua_getupvalue,
but n cannot be greater than the number of upvalues.
lua_upvaluejoin[-0, +0, –]
void lua_upvaluejoin (lua_State *L, int funcindex1, int n1,
int funcindex2, int n2);
Make the n1-th upvalue of the Lua closure at index funcindex1
refer to the n2-th upvalue of the Lua closure at index funcindex2.
The auxiliary library provides several convenient functions to interface C with Lua. While the basic API provides the primitive functions for all interactions between C and Lua, the auxiliary library provides higher-level functions for some common tasks.
All functions and types from the auxiliary library
are defined in header file lauxlib.h and
have a prefix luaL_.
All functions in the auxiliary library are built on top of the basic API, and so they provide nothing that cannot be done with that API. Nevertheless, the use of the auxiliary library ensures more consistency to your code.
Several functions in the auxiliary library use internally some extra stack slots. When a function in the auxiliary library uses less than five slots, it does not check the stack size; it simply assumes that there are enough slots.
Several functions in the auxiliary library are used to
check C function arguments.
Because the error message is formatted for arguments
(e.g., "bad argument #1"),
you should not use these functions for other stack values.
Functions called luaL_check*
always raise an error if the check is not satisfied.
+
+
Here we list all functions and types from the auxiliary library in alphabetical order.
luaL_addchar[-?, +?, m]
void luaL_addchar (luaL_Buffer *B, char c);
Adds the byte c to the buffer B
(see luaL_Buffer).
+
luaL_addgsub+[-0, +0, m] +
const void luaL_addgsub (luaL_Buffer *B, const char *s, + const char *p, const char *r);+ +
+Adds a copy of the string s to the buffer B (see luaL_Buffer),
+replacing any occurrence of the string p
+with the string r.
+
+
+
+
+
luaL_addlstring[-?, +?, m]
void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);
Adds the string pointed to by s with length l to
the buffer B
(see luaL_Buffer).
The string can contain embedded zeros.
luaL_addsize[-?, +?, –]
void luaL_addsize (luaL_Buffer *B, size_t n);
-Adds to the buffer B (see luaL_Buffer)
+Adds to the buffer B
a string of length n previously copied to the
buffer area (see luaL_prepbuffer).
luaL_addstring[-?, +?, m]
void luaL_addstring (luaL_Buffer *B, const char *s);
Adds the zero-terminated string pointed to by s
to the buffer B
(see luaL_Buffer).
luaL_addvalue[-1, +?, m]
void luaL_addvalue (luaL_Buffer *B);
-Adds the value at the top of the stack
+Adds the value on the top of the stack
to the buffer B
(see luaL_Buffer).
Pops the value.
This is the only function on string buffers that can (and must) be called with an extra element on the stack, which is the value to be added to the buffer.
luaL_argcheck[-0, +0, v]
void luaL_argcheck (lua_State *L,
int cond,
int arg,
const char *extramsg);
Checks whether cond is true.
If it is not, raises an error with a standard message (see luaL_argerror).
luaL_argerror[-0, +0, v]
int luaL_argerror (lua_State *L, int arg, const char *extramsg);
Raises an error reporting a problem with argument arg
of the C function that called it,
using a standard message
that includes extramsg as a comment:
bad argument #arg to 'funcname' (extramsg)
This function never returns. +
luaL_argexpected+[-0, +0, v] +
void luaL_argexpected (lua_State *L, + int cond, + int arg, + const char *tname);+ +
+Checks whether cond is true.
+If it is not, raises an error about the type of the argument arg
+with a standard message (see luaL_typeerror).
+
+
+
+
+
luaL_Buffertypedef struct luaL_Buffer luaL_Buffer;
Type for a string buffer.
A string buffer allows C code to build Lua strings piecemeal. Its pattern of use is as follows:
b of type luaL_Buffer.luaL_buffinit(L, &b).luaL_add* functions.
luaL_pushresult(&b).
This call leaves the final string on the top of the stack.
-If you know beforehand the total size of the resulting string, +If you know beforehand the maximum size of the resulting string, you can use the buffer like this:
b of type luaL_Buffer.sz with a call luaL_buffinitsize(L, &b, sz).luaL_pushresultsize(&b, sz),
where sz is the total size of the resulting string
-copied into that space.
+copied into that space (which may be less than or
+equal to the preallocated size).
During its normal operation,
a string buffer uses a variable number of stack slots.
So, while using a buffer, you cannot assume that you know where
the top of the stack is.
You can use the stack between successive calls to buffer operations
as long as that use is balanced;
that is,
when you call a buffer operation,
the stack is at the same level
it was immediately after the previous buffer operation.
(The only exception to this rule is luaL_addvalue.)
-After calling luaL_pushresult the stack is back to its
-level when the buffer was initialized,
+After calling luaL_pushresult,
+the stack is back to its level when the buffer was initialized,
plus the final string on its top.
+
luaL_buffaddr+[-0, +0, –] +
char *luaL_buffaddr (luaL_Buffer *B);+ +
+Returns the address of the current content of buffer B
+(see luaL_Buffer).
+Note that any addition to the buffer may invalidate this address.
+
+
+
+
+
luaL_buffinit[-0, +0, –]
void luaL_buffinit (lua_State *L, luaL_Buffer *B);
-Initializes a buffer B.
+Initializes a buffer B
+(see luaL_Buffer).
This function does not allocate any space;
-the buffer must be declared as a variable
+the buffer must be declared as a variable.
+
+
+
+
+
+
luaL_bufflen+[-0, +0, –] +
size_t luaL_bufflen (luaL_Buffer *B);+ +
+Returns the length of the current content of buffer B
(see luaL_Buffer).
luaL_buffinitsize[-?, +?, m]
char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);
-Equivalent to the sequence
-luaL_buffinit, luaL_prepbuffsize.
+Equivalent to the sequence
+luaL_buffinit, luaL_prepbuffsize.
+
+
+
+
+
+
luaL_buffsub+[-0, +0, –] +
void luaL_buffsub (luaL_Buffer *B, int n);+ +
+Removes n bytes from the the buffer B
+(see luaL_Buffer).
+The buffer must have at least that many bytes.
luaL_callmeta[-0, +(0|1), e]
int luaL_callmeta (lua_State *L, int obj, const char *e);
Calls a metamethod.
If the object at index obj has a metatable and this
metatable has a field e,
this function calls this field passing the object as its only argument.
In this case this function returns true and pushes onto the
stack the value returned by the call.
If there is no metatable or no metamethod,
-this function returns false (without pushing any value on the stack).
+this function returns false without pushing any value on the stack.
luaL_checkany[-0, +0, v]
void luaL_checkany (lua_State *L, int arg);
Checks whether the function has an argument
of any type (including nil) at position arg.
luaL_checkinteger[-0, +0, v]
lua_Integer luaL_checkinteger (lua_State *L, int arg);
Checks whether the function argument arg is an integer
(or can be converted to an integer)
-and returns this integer cast to a lua_Integer.
+and returns this integer.
luaL_checklstring[-0, +0, v]
const char *luaL_checklstring (lua_State *L, int arg, size_t *l);
Checks whether the function argument arg is a string
and returns this string;
-if l is not NULL fills *l
+if l is not NULL fills its referent
with the string's length.
This function uses lua_tolstring to get its result,
so all conversions and caveats of that function apply here.
luaL_checknumber[-0, +0, v]
lua_Number luaL_checknumber (lua_State *L, int arg);
Checks whether the function argument arg is a number
-and returns this number.
+and returns this number converted to a lua_Number.
luaL_checkoption[-0, +0, v]
int luaL_checkoption (lua_State *L,
int arg,
const char *def,
const char *const lst[]);
Checks whether the function argument arg is a string and
searches for this string in the array lst
(which must be NULL-terminated).
Returns the index in the array where the string was found.
Raises an error if the argument is not a string or
if the string cannot be found.
If def is not NULL,
the function uses def as a default value when
there is no argument arg or when this argument is nil.
This is a useful function for mapping strings to C enums. (The usual convention in Lua libraries is to use strings instead of numbers to select options.)
luaL_checkstack[-0, +0, v]
void luaL_checkstack (lua_State *L, int sz, const char *msg);
Grows the stack size to top + sz elements,
raising an error if the stack cannot grow to that size.
msg is an additional text to go into the error message
(or NULL for no additional text).
luaL_checkstring[-0, +0, v]
const char *luaL_checkstring (lua_State *L, int arg);
Checks whether the function argument arg is a string
and returns this string.
This function uses lua_tolstring to get its result,
so all conversions and caveats of that function apply here.
luaL_checktype[-0, +0, v]
void luaL_checktype (lua_State *L, int arg, int t);
Checks whether the function argument arg has type t.
See lua_type for the encoding of types for t.
luaL_checkudata[-0, +0, v]
void *luaL_checkudata (lua_State *L, int arg, const char *tname);
Checks whether the function argument arg is a userdata
of the type tname (see luaL_newmetatable) and
-returns the userdata address (see lua_touserdata).
+returns the userdata's memory-block address (see lua_touserdata).
luaL_checkversion[-0, +0, v]
void luaL_checkversion (lua_State *L);
-Checks whether the core running the call, -the core that created the Lua state, -and the code making the call are all using the same version of Lua. -Also checks whether the core running the call -and the core that created the Lua state -are using the same address space. +Checks whether the code making the call and the Lua library being called +are using the same version of Lua and the same numeric types.
luaL_dofile-[-0, +?, e] +[-0, +?, m]
int luaL_dofile (lua_State *L, const char *filename);
Loads and runs the given file. It is defined as the following macro:
(luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0))
-It returns false if there are no errors
-or true in case of errors.
+It returns LUA_OK if there are no errors,
+or an error code in case of errors (see §4.4.1).
luaL_dostring[-0, +?, –]
int luaL_dostring (lua_State *L, const char *str);
Loads and runs the given string. It is defined as the following macro:
(luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0))
-It returns false if there are no errors
-or true in case of errors.
+It returns LUA_OK if there are no errors,
+or an error code in case of errors (see §4.4.1).
luaL_error[-0, +0, v]
int luaL_error (lua_State *L, const char *fmt, ...);
Raises an error.
The error message format is given by fmt
plus any extra arguments,
following the same rules of lua_pushfstring.
It also adds at the beginning of the message the file name and
the line number where the error occurred,
if this information is available.
This function never returns,
but it is an idiom to use it in C functions
as return luaL_error(args).
luaL_execresult[-0, +3, m]
int luaL_execresult (lua_State *L, int stat);
This function produces the return values for
process-related functions in the standard library
(os.execute and io.close).
luaL_fileresult[-0, +(1|3), m]
int luaL_fileresult (lua_State *L, int stat, const char *fname);
This function produces the return values for
file-related functions in the standard library
(io.open, os.rename, file:seek, etc.).
luaL_getmetafield[-0, +(0|1), m]
int luaL_getmetafield (lua_State *L, int obj, const char *e);
Pushes onto the stack the field e from the metatable
of the object at index obj and returns the type of the pushed value.
If the object does not have a metatable,
or if the metatable does not have this field,
pushes nothing and returns LUA_TNIL.
luaL_getmetatable[-0, +1, m]
int luaL_getmetatable (lua_State *L, const char *tname);
-Pushes onto the stack the metatable associated with name tname
-in the registry (see luaL_newmetatable)
-(nil if there is no metatable associated with that name).
+Pushes onto the stack the metatable associated with the name tname
+in the registry (see luaL_newmetatable),
+or nil if there is no metatable associated with that name.
Returns the type of the pushed value.
luaL_getsubtable[-0, +1, e]
int luaL_getsubtable (lua_State *L, int idx, const char *fname);
Ensures that the value t[fname],
where t is the value at index idx,
is a table,
and pushes that table onto the stack.
Returns true if it finds a previous table there
and false if it creates a new table.
luaL_gsub[-0, +1, m]
const char *luaL_gsub (lua_State *L,
const char *s,
const char *p,
const char *r);
-Creates a copy of string s by replacing
-any occurrence of the string p
+Creates a copy of string s,
+replacing any occurrence of the string p
with the string r.
Pushes the resulting string on the stack and returns it.
luaL_len[-0, +0, e]
lua_Integer luaL_len (lua_State *L, int index);
Returns the "length" of the value at the given index
as a number;
it is equivalent to the '#' operator in Lua (see §3.4.7).
Raises an error if the result of the operation is not an integer.
-(This case only can happen through metamethods.)
+(This case can only happen through metamethods.)
luaL_loadbuffer[-0, +1, –]
int luaL_loadbuffer (lua_State *L,
const char *buff,
size_t sz,
const char *name);
Equivalent to luaL_loadbufferx with mode equal to NULL.
luaL_loadbufferx[-0, +1, –]
int luaL_loadbufferx (lua_State *L,
const char *buff,
size_t sz,
const char *name,
const char *mode);
Loads a buffer as a Lua chunk.
This function uses lua_load to load the chunk in the
buffer pointed to by buff with size sz.
This function returns the same results as lua_load.
name is the chunk name,
used for debug information and error messages.
-The string mode works as in function lua_load.
+The string mode works as in the function lua_load.
luaL_loadfile[-0, +1, m]
int luaL_loadfile (lua_State *L, const char *filename);
Equivalent to luaL_loadfilex with mode equal to NULL.
luaL_loadfilex[-0, +1, m]
int luaL_loadfilex (lua_State *L, const char *filename,
const char *mode);
Loads a file as a Lua chunk.
This function uses lua_load to load the chunk in the file
named filename.
If filename is NULL,
then it loads from the standard input.
The first line in the file is ignored if it starts with a #.
-The string mode works as in function lua_load.
+The string mode works as in the function lua_load.
-This function returns the same results as lua_load,
-but it has an extra error code LUA_ERRFILE
-for file-related errors
-(e.g., it cannot open or read the file).
+This function returns the same results as lua_load
+or LUA_ERRFILE for file-related errors.
As lua_load, this function only loads the chunk;
it does not run it.
luaL_loadstring[-0, +1, –]
int luaL_loadstring (lua_State *L, const char *s);
Loads a string as a Lua chunk.
This function uses lua_load to load the chunk in
the zero-terminated string s.
This function returns the same results as lua_load.
Also as lua_load, this function only loads the chunk;
it does not run it.
luaL_newlib[-0, +1, m]
void luaL_newlib (lua_State *L, const luaL_Reg l[]);
Creates a new table and registers there
-the functions in list l.
+the functions in the list l.
It is implemented as the following macro:
(luaL_newlibtable(L,l), luaL_setfuncs(L,l,0))
The array l must be the actual array,
not a pointer to it.
luaL_newlibtable[-0, +1, m]
void luaL_newlibtable (lua_State *L, const luaL_Reg l[]);
Creates a new table with a size optimized
to store all entries in the array l
(but does not actually store them).
It is intended to be used in conjunction with luaL_setfuncs
(see luaL_newlib).
It is implemented as a macro.
The array l must be the actual array,
not a pointer to it.
luaL_newmetatable[-0, +1, m]
int luaL_newmetatable (lua_State *L, const char *tname);
If the registry already has the key tname,
returns 0.
Otherwise,
creates a new table to be used as a metatable for userdata,
adds to this new table the pair __name = tname,
adds to the registry the pair [tname] = new table,
and returns 1.
-(The entry __name is used by some error-reporting functions.)
-In both cases pushes onto the stack the final value associated
+In both cases,
+the function pushes onto the stack the final value associated
with tname in the registry.
luaL_newstate[-0, +0, –]
lua_State *luaL_newstate (void);
Creates a new Lua state.
It calls lua_newstate with an
-allocator based on the standard C realloc function
-and then sets a panic function (see §4.6) that prints
-an error message to the standard error output in case of fatal
-errors.
+allocator based on the standard C allocation functions
+and then sets a warning function and a panic function (see §4.4)
+that print messages to the standard error output.
Returns the new state,
or NULL if there is a memory allocation error.
luaL_openlibs[-0, +0, e]
void luaL_openlibs (lua_State *L);
Opens all standard Lua libraries into the given state.
luaL_opt-[-0, +0, e] +[-0, +0, –]
T luaL_opt (L, func, arg, dflt);
This macro is defined as follows:
(lua_isnoneornil(L,(arg)) ? (dflt) : func(L,(arg)))
In words, if the argument arg is nil or absent,
the macro results in the default dflt.
Otherwise, it results in the result of calling func
with the state L and the argument index arg as
arguments.
Note that it evaluates the expression dflt only if needed.
luaL_optinteger[-0, +0, v]
lua_Integer luaL_optinteger (lua_State *L,
int arg,
lua_Integer d);
If the function argument arg is an integer
-(or convertible to an integer),
+(or it is convertible to an integer),
returns this integer.
If this argument is absent or is nil,
returns d.
Otherwise, raises an error.
luaL_optlstring[-0, +0, v]
const char *luaL_optlstring (lua_State *L,
int arg,
const char *d,
size_t *l);
If the function argument arg is a string,
returns this string.
If this argument is absent or is nil,
returns d.
Otherwise, raises an error.
If l is not NULL,
-fills the position *l with the result's length.
+fills its referent with the result's length.
If the result is NULL
(only possible when returning d and d == NULL),
its length is considered zero.
This function uses lua_tolstring to get its result,
so all conversions and caveats of that function apply here.
luaL_optnumber[-0, +0, v]
lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number d);
If the function argument arg is a number,
-returns this number.
+returns this number as a lua_Number.
If this argument is absent or is nil,
returns d.
Otherwise, raises an error.
luaL_optstring[-0, +0, v]
const char *luaL_optstring (lua_State *L,
int arg,
const char *d);
If the function argument arg is a string,
returns this string.
If this argument is absent or is nil,
returns d.
Otherwise, raises an error.
luaL_prepbuffer[-?, +?, m]
char *luaL_prepbuffer (luaL_Buffer *B);
Equivalent to luaL_prepbuffsize
with the predefined size LUAL_BUFFERSIZE.
luaL_prepbuffsize[-?, +?, m]
char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);
Returns an address to a space of size sz
where you can copy a string to be added to buffer B
(see luaL_Buffer).
After copying the string into this space you must call
luaL_addsize with the size of the string to actually add
it to the buffer.
+
luaL_pushfail+[-0, +1, –] +
void luaL_pushfail (lua_State *L);+ +
+Pushes the fail value onto the stack (see §6). + + + + +
luaL_pushresult[-?, +1, m]
void luaL_pushresult (luaL_Buffer *B);
Finishes the use of buffer B leaving the final string on
the top of the stack.
luaL_pushresultsize[-?, +1, m]
void luaL_pushresultsize (luaL_Buffer *B, size_t sz);
Equivalent to the sequence luaL_addsize, luaL_pushresult.
luaL_ref[-1, +0, m]
int luaL_ref (lua_State *L, int t);
Creates and returns a reference,
in the table at index t,
-for the object at the top of the stack (and pops the object).
+for the object on the top of the stack (and pops the object).
A reference is a unique integer key.
-As long as you do not manually add integer keys into table t,
+As long as you do not manually add integer keys into the table t,
luaL_ref ensures the uniqueness of the key it returns.
-You can retrieve an object referred by reference r
+You can retrieve an object referred by the reference r
by calling lua_rawgeti(L, t, r).
-Function luaL_unref frees a reference and its associated object.
+The function luaL_unref frees a reference.
-If the object at the top of the stack is nil,
+If the object on the top of the stack is nil,
luaL_ref returns the constant LUA_REFNIL.
The constant LUA_NOREF is guaranteed to be different
from any reference returned by luaL_ref.
luaL_Regtypedef struct luaL_Reg {
const char *name;
lua_CFunction func;
} luaL_Reg;
Type for arrays of functions to be registered by
luaL_setfuncs.
name is the function name and func is a pointer to
the function.
Any array of luaL_Reg must end with a sentinel entry
in which both name and func are NULL.
luaL_requiref[-0, +1, e]
void luaL_requiref (lua_State *L, const char *modname,
lua_CFunction openf, int glb);
-If modname is not already present in package.loaded,
-calls function openf with string modname as an argument
-and sets the call result in package.loaded[modname],
+If package.loaded[modname] is not true,
+calls the function openf with the string modname as an argument
+and sets the call result to package.loaded[modname],
as if that function has been called through require.
If glb is true,
-also stores the module into global modname.
+also stores the module into the global modname.
Leaves a copy of the module on the stack.
luaL_setfuncs[-nup, +0, m]
void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);
Registers all functions in the array l
(see luaL_Reg) into the table on the top of the stack
(below optional upvalues, see next).
When nup is not zero,
-all functions are created sharing nup upvalues,
-which must be previously pushed on the stack
+all functions are created with nup upvalues,
+initialized with copies of the nup values
+previously pushed on the stack
on top of the library table.
These values are popped from the stack after the registration.
luaL_setmetatable[-0, +0, –]
void luaL_setmetatable (lua_State *L, const char *tname);
-Sets the metatable of the object at the top of the stack
+Sets the metatable of the object on the top of the stack
as the metatable associated with name tname
in the registry (see luaL_newmetatable).
luaL_Streamtypedef struct luaL_Stream {
FILE *f;
lua_CFunction closef;
} luaL_Stream;
-The standard representation for file handles, -which is used by the standard I/O library. +The standard representation for file handles +used by the standard I/O library.
A file handle is implemented as a full userdata,
with a metatable called LUA_FILEHANDLE
(where LUA_FILEHANDLE is a macro with the actual metatable's name).
The metatable is created by the I/O library
(see luaL_newmetatable).
This userdata must start with the structure luaL_Stream;
it can contain other data after this initial structure.
-Field f points to the corresponding C stream
+The field f points to the corresponding C stream
(or it can be NULL to indicate an incompletely created handle).
-Field closef points to a Lua function
+The field closef points to a Lua function
that will be called to close the stream
when the handle is closed or collected;
this function receives the file handle as its sole argument and
-must return either true (in case of success)
-or nil plus an error message (in case of error).
+must return either a true value, in case of success,
+or a false value plus an error message, in case of error.
Once Lua calls this field,
it changes the field value to NULL
to signal that the handle is closed.
luaL_testudata[-0, +0, m]
void *luaL_testudata (lua_State *L, int arg, const char *tname);
This function works like luaL_checkudata,
except that, when the test fails,
it returns NULL instead of raising an error.
luaL_tolstring[-0, +1, e]
const char *luaL_tolstring (lua_State *L, int idx, size_t *len);
Converts any Lua value at the given index to a C string
in a reasonable format.
The resulting string is pushed onto the stack and also
-returned by the function.
+returned by the function (see §4.1.3).
If len is not NULL,
the function also sets *len with the string length.
If the value has a metatable with a __tostring field,
then luaL_tolstring calls the corresponding metamethod
with the value as argument,
and uses the result of the call as its result.
luaL_traceback[-0, +1, m]
void luaL_traceback (lua_State *L, lua_State *L1, const char *msg,
int level);
Creates and pushes a traceback of the stack L1.
-If msg is not NULL it is appended
+If msg is not NULL, it is appended
at the beginning of the traceback.
The level parameter tells at which level
to start the traceback.
+
luaL_typeerror+[-0, +0, v] +
const char *luaL_typeerror (lua_State *L, + int arg, + const char *tname);+ +
+Raises a type error for the argument arg
+of the C function that called it,
+using a standard message;
+tname is a "name" for the expected type.
+This function never returns.
+
+
+
+
+
luaL_typename[-0, +0, –]
const char *luaL_typename (lua_State *L, int index);
Returns the name of the type of the value at the given index.
luaL_unref[-0, +0, –]
void luaL_unref (lua_State *L, int t, int ref);
-Releases reference ref from the table at index t
+Releases the reference ref from the table at index t
(see luaL_ref).
The entry is removed from the table,
so that the referred object can be collected.
The reference ref is also freed to be used again.
If ref is LUA_NOREF or LUA_REFNIL,
luaL_unref does nothing.
luaL_where[-0, +1, m]
void luaL_where (lua_State *L, int lvl);
Pushes onto the stack a string identifying the current position
of the control at level lvl in the call stack.
Typically this string has the following format:
chunkname:currentline:
Level 0 is the running function, level 1 is the function that called the running function, etc.
This function is used to build a prefix for error messages. -
The standard Lua libraries provide useful functions
-that are implemented directly through the C API.
+that are implemented in C through the C API.
Some of these functions provide essential services to the language
(e.g., type and getmetatable);
-others provide access to "outside" services (e.g., I/O);
+others provide access to outside services (e.g., I/O);
and others could be implemented in Lua itself,
-but are quite useful or have critical performance requirements that
+but that for different reasons
deserve an implementation in C (e.g., table.sort).
All libraries are implemented through the official C API
and are provided as separate C modules.
+Unless otherwise noted,
+these library functions do not adjust its number of arguments
+to its expected parameters.
+For instance, a function documented as foo(arg)
+should not be called without an argument.
+
+
+
+The notation fail means a false value representing
+some kind of failure.
+(Currently, fail is equal to nil,
+but that may change in future versions.
+The recommendation is to always test the success of these functions
+with (not status), instead of (status == nil).)
+
+
+
Currently, Lua has the following standard libraries:
Except for the basic and the package libraries, each library provides all its functions as fields of a global table or as methods of its objects.
To have access to these libraries,
the C host program should call the luaL_openlibs function,
which opens all standard libraries.
Alternatively,
the host program can open them individually by using
luaL_requiref to call
luaopen_base (for the basic library),
luaopen_package (for the package library),
luaopen_coroutine (for the coroutine library),
luaopen_string (for the string library),
-luaopen_utf8 (for the UTF8 library),
+luaopen_utf8 (for the UTF-8 library),
luaopen_table (for the table library),
luaopen_math (for the mathematical library),
luaopen_io (for the I/O library),
luaopen_os (for the operating system library),
and luaopen_debug (for the debug library).
These functions are declared in lualib.h.
+
+
The basic library provides core functions to Lua. If you do not include this library in your application, you should check carefully whether you need to provide implementations for some of its facilities.
assert (v [, message])
-Calls error if
+Raises an error if
the value of its argument v is false (i.e., nil or false);
otherwise, returns all its arguments.
In case of error,
message is the error object;
when absent, it defaults to "assertion failed!"
collectgarbage ([opt [, arg]])
This function is a generic interface to the garbage collector.
It performs different functions according to its first argument, opt:
collect":
-performs a full garbage-collection cycle.
+Performs a full garbage-collection cycle.
This is the default option.
stop":
-stops automatic execution of the garbage collector.
+Stops automatic execution of the garbage collector.
The collector will run only when explicitly invoked,
until a call to restart it.
restart":
-restarts automatic execution of the garbage collector.
+Restarts automatic execution of the garbage collector.
count":
-returns the total memory in use by Lua in Kbytes.
+Returns the total memory in use by Lua in Kbytes.
The value has a fractional part,
so that it multiplied by 1024
-gives the exact number of bytes in use by Lua
-(except for overflows).
+gives the exact number of bytes in use by Lua.
step":
-performs a garbage-collection step.
+Performs a garbage-collection step.
The step "size" is controlled by arg.
With a zero value,
the collector will perform one basic (indivisible) step.
For non-zero values,
the collector will perform as if that amount of memory
-(in KBytes) had been allocated by Lua.
+(in Kbytes) had been allocated by Lua.
Returns true if the step finished a collection cycle.
setpause":
-sets arg as the new value for the pause of
-the collector (see §2.5).
-Returns the previous value for pause.
+isrunning":
+Returns a boolean that tells whether the collector is running
+(i.e., not stopped).
setstepmul":
-sets arg as the new value for the step multiplier of
-the collector (see §2.5).
-Returns the previous value for step.
+incremental":
+Change the collector mode to incremental.
+This option can be followed by three numbers:
+the garbage-collector pause,
+the step multiplier,
+and the step size (see §2.5.1).
+A zero means to not change that value.
isrunning":
-returns a boolean that tells whether the collector is running
-(i.e., not stopped).
+generational":
+Change the collector mode to generational.
+This option can be followed by two numbers:
+the garbage-collector minor multiplier
+and the major multiplier (see §2.5.2).
+A zero means to not change that value.
+See §2.5 for more details about garbage collection +and some of these options. +
dofile ([filename])dofile executes the contents of the standard input (stdin).
+dofile executes the content of the standard input (stdin).
Returns all values returned by the chunk.
In case of errors, dofile propagates the error
-to its caller (that is, dofile does not run in protected mode).
+to its caller.
+(That is, dofile does not run in protected mode.)
error (message [, level])message as the error object.
-Function error never returns.
+Raises an error (see §2.3) with @{message} as the error object.
+This function never returns.
Usually, error adds some information about the error position
at the beginning of the message, if the message is a string.
The level argument specifies how to get the error position.
With level 1 (the default), the error position is where the
error function was called.
Level 2 points the error to where the function
that called error was called; and so on.
Passing a level 0 avoids the addition of error position information
to the message.
_G
getmetatable (object)
If object does not have a metatable, returns nil.
Otherwise,
if the object's metatable has a __metatable field,
returns the associated value.
Otherwise, returns the metatable of the given object.
ipairs (t)
Returns three values (an iterator function, the table t, and 0)
so that the construction
for i,v in ipairs(t) do body end
will iterate over the key–value pairs
(1,t[1]), (2,t[2]), ...,
-up to the first nil value.
+up to the first absent index.
load (chunk [, chunkname [, mode [, env]]])Loads a chunk.
If chunk is a string, the chunk is this string.
If chunk is a function,
load calls it repeatedly to get the chunk pieces.
Each call to chunk must return a string that concatenates
with previous results.
A return of an empty string, nil, or no value signals the end of the chunk.
If there are no syntactic errors,
-returns the compiled chunk as a function;
-otherwise, returns nil plus the error message.
+load returns the compiled chunk as a function;
+otherwise, it returns fail plus the error message.
-If the resulting function has upvalues,
-the first upvalue is set to the value of env,
-if that parameter is given,
-or to the value of the global environment.
-Other upvalues are initialized with nil.
-(When you load a main chunk,
+When you load a main chunk,
the resulting function will always have exactly one upvalue,
the _ENV variable (see §2.2).
However,
when you load a binary chunk created from a function (see string.dump),
-the resulting function can have an arbitrary number of upvalues.)
+the resulting function can have an arbitrary number of upvalues,
+and there is no guarantee that its first upvalue will be
+the _ENV variable.
+(A non-main function may not even have an _ENV upvalue.)
+
+
+
+Regardless, if the resulting function has any upvalues,
+its first upvalue is set to the value of env,
+if that parameter is given,
+or to the value of the global environment.
+Other upvalues are initialized with nil.
All upvalues are fresh, that is,
they are not shared with any other function.
chunkname is used as the name of the chunk for error messages
-and debug information (see §4.9).
+and debug information (see §4.7).
When absent,
it defaults to chunk, if chunk is a string,
or to "=(load)" otherwise.
The string mode controls whether the chunk can be text or binary
(that is, a precompiled chunk).
It may be the string "b" (only binary chunks),
"t" (only text chunks),
or "bt" (both binary and text).
The default is "bt".
-Lua does not check the consistency of binary chunks.
-Maliciously crafted binary chunks can crash
-the interpreter.
+It is safe to load malformed binary chunks;
+load signals an appropriate error.
+However,
+Lua does not check the consistency of the code inside binary chunks;
+running maliciously crafted bytecode can crash the interpreter.
loadfile ([filename [, mode [, env]]])
Similar to load,
but gets the chunk from file filename
or from the standard input,
if no file name is given.
next (table [, index])
Allows a program to traverse all fields of a table.
Its first argument is a table and its second argument
is an index in this table.
-next returns the next index of the table
+A call to next returns the next index of the table
and its associated value.
When called with nil as its second argument,
next returns an initial index
and its associated value.
When called with the last index,
or with nil in an empty table,
next returns nil.
If the second argument is absent, then it is interpreted as nil.
In particular,
you can use next(t) to check whether a table is empty.
The order in which the indices are enumerated is not specified, even for numeric indices. (To traverse a table in numerical order, use a numerical for.)
The behavior of next is undefined if,
during the traversal,
you assign any value to a non-existent field in the table.
You may however modify existing fields.
-In particular, you may clear existing fields.
+In particular, you may set existing fields to nil.
pairs (t)
If t has a metamethod __pairs,
calls it with t as argument and returns the first three
results from the call.
Otherwise,
returns three values: the next function, the table t, and nil,
so that the construction
for k,v in pairs(t) do body end
will iterate over all key–value pairs of table t.
See function next for the caveats of modifying
the table during its traversal.
pcall (f [, arg1, ···])
-Calls function f with
+Calls the function f with
the given arguments in protected mode.
This means that any error inside f is not propagated;
instead, pcall catches the error
and returns a status code.
Its first result is the status code (a boolean),
which is true if the call succeeds without errors.
In such case, pcall also returns all results from the call,
after this first result.
-In case of any error, pcall returns false plus the error message.
+In case of any error, pcall returns false plus the error object.
+Note that errors caught by pcall do not call a message handler.
print (···)stdout,
-using the tostring function to convert each argument to a string.
-print is not intended for formatted output,
+converting each argument to a string
+following the same rules of tostring.
+
+
+
+The function print is not intended for formatted output,
but only as a quick way to show a value,
for instance for debugging.
For complete control over the output,
use string.format and io.write.
rawequal (v1, v2)v1 is equal to v2,
without invoking the __eq metamethod.
Returns a boolean.
rawget (table, index)table[index],
-without invoking the __index metamethod.
+without using the __index metavalue.
table must be a table;
index may be any value.
rawlen (v)v,
which must be a table or a string,
without invoking the __len metamethod.
Returns an integer.
rawset (table, index, value)table[index] to value,
-without invoking the __newindex metamethod.
+without using the __newindex metavalue.
table must be a table,
index any value different from nil and NaN,
and value any Lua value.
This function returns table.
select (index, ···)
If index is a number,
returns all arguments after argument number index;
a negative number indexes from the end (-1 is the last argument).
Otherwise, index must be the string "#",
and select returns the total number of extra arguments it received.
setmetatable (table, metatable)
Sets the metatable for the given table.
-(To change the metatable of other types from Lua code,
-you must use the debug library (§6.10).)
If metatable is nil,
removes the metatable of the given table.
If the original metatable has a __metatable field,
raises an error.
This function returns table.
+
+To change the metatable of other types from Lua code, +you must use the debug library (§6.10). + +
tonumber (e [, base])
When called with no base,
tonumber tries to convert its argument to a number.
If the argument is already a number or
a string convertible to a number,
then tonumber returns this number;
-otherwise, it returns nil.
+otherwise, it returns fail.
The conversion of strings can result in integers or floats, according to the lexical conventions of Lua (see §3.1). -(The string may have leading and trailing spaces and a sign.) +The string may have leading and trailing spaces and a sign.
When called with base,
then e must be a string to be interpreted as
an integer numeral in that base.
The base may be any integer between 2 and 36, inclusive.
In bases above 10, the letter 'A' (in either upper or lower case)
represents 10, 'B' represents 11, and so forth,
with 'Z' representing 35.
If the string e is not a valid numeral in the given base,
-the function returns nil.
+the function returns fail.
tostring (v)
Receives a value of any type and
converts it to a string in a human-readable format.
-(For complete control of how numbers are converted,
-use string.format.)
If the metatable of v has a __tostring field,
then tostring calls the corresponding value
with v as argument,
and uses the result of the call as its result.
+Otherwise, if the metatable of v has a __name field
+with a string value,
+tostring may use that string in its final result.
+
+
+
+For complete control of how numbers are converted,
+use string.format.
type (v)
Returns the type of its only argument, coded as a string.
The possible results of this function are
"nil" (a string, not the value nil),
"number",
"string",
"boolean",
"table",
"function",
"thread",
and "userdata".
_VERSION
A global variable (not a function) that
holds a string containing the running Lua version.
-The current value of this variable is "Lua 5.3".
+The current value of this variable is "Lua 5.4".
+
+
+
+
+
+
warn (msg1, ···)+Emits a warning with a message composed by the concatenation +of all its arguments (which should be strings). + + +
+By convention,
+a one-piece message starting with '@'
+is intended to be a control message,
+which is a message to the warning system itself.
+In particular, the standard warning function in Lua
+recognizes the control messages "@off",
+to stop the emission of warnings,
+and "@on", to (re)start the emission;
+it ignores unknown control messages.
xpcall (f, msgh [, arg1, ···])
This function is similar to pcall,
except that it sets a new message handler msgh.
This library comprises the operations to manipulate coroutines,
which come inside the table coroutine.
See §2.6 for a general description of coroutines.
+
+
coroutine.close (co)
+Closes coroutine co,
+that is,
+closes all its pending to-be-closed variables
+and puts the coroutine in a dead state.
+The given coroutine must be dead or suspended.
+In case of error closing some variable,
+returns false plus the error object;
+otherwise returns true.
+
+
+
+
coroutine.create (f)
Creates a new coroutine, with body f.
f must be a function.
Returns this new coroutine,
an object with type "thread".
-
coroutine.isyieldable ()coroutine.isyieldable ([co])
-Returns true when the running coroutine can yield.
+Returns true when the coroutine co can yield.
+The default for co is the running coroutine.
-A running coroutine is yieldable if it is not the main thread and +A coroutine is yieldable if it is not the main thread and it is not inside a non-yieldable C function.
coroutine.resume (co [, val1, ···])
Starts or continues the execution of coroutine co.
The first time you resume a coroutine,
it starts running its body.
The values val1, ... are passed
as the arguments to the body function.
If the coroutine has yielded,
resume restarts it;
the values val1, ... are passed
as the results from the yield.
If the coroutine runs without any errors,
resume returns true plus any values passed to yield
(when the coroutine yields) or any values returned by the body function
(when the coroutine terminates).
If there is any error,
resume returns false plus the error message.
coroutine.running ()Returns the running coroutine plus a boolean, true when the running coroutine is the main one.
coroutine.status (co)
-Returns the status of coroutine co, as a string:
+Returns the status of the coroutine co, as a string:
"running",
-if the coroutine is running (that is, it called status);
+if the coroutine is running
+(that is, it is the one that called status);
"suspended", if the coroutine is suspended in a call to yield,
or if it has not started running yet;
"normal" if the coroutine is active but not running
(that is, it has resumed another coroutine);
and "dead" if the coroutine has finished its body function,
or if it has stopped with an error.
coroutine.wrap (f)
-Creates a new coroutine, with body f.
+Creates a new coroutine, with body f;
f must be a function.
Returns a function that resumes the coroutine each time it is called.
-Any arguments passed to the function behave as the
+Any arguments passed to this function behave as the
extra arguments to resume.
-Returns the same values returned by resume,
+The function returns the same values returned by resume,
except the first boolean.
-In case of error, propagates the error.
+In case of error,
+the function closes the coroutine and propagates the error.
coroutine.yield (···)
Suspends the execution of the calling coroutine.
Any arguments to yield are passed as extra results to resume.
The package library provides basic
facilities for loading modules in Lua.
It exports one function directly in the global environment:
require.
-Everything else is exported in a table package.
+Everything else is exported in the table package.
require (modname)
Loads the given module.
The function starts by looking into the package.loaded table
to determine whether modname is already loaded.
If it is, then require returns the value stored
at package.loaded[modname].
+(The absence of a second result in this case
+signals that this call did not have to load the module.)
Otherwise, it tries to find a loader for the module.
To find a loader,
-require is guided by the package.searchers sequence.
-By changing this sequence,
+require is guided by the table package.searchers.
+Each item in this table is a search function,
+that searches for the module in a particular way.
+By changing this table,
we can change how require looks for a module.
The following explanation is based on the default configuration
for package.searchers.
First require queries package.preload[modname].
If it has a value,
this value (which must be a function) is the loader.
Otherwise require searches for a Lua loader using the
path stored in package.path.
If that also fails, it searches for a C loader using the
path stored in package.cpath.
If that also fails,
it tries an all-in-one loader (see package.searchers).
Once a loader is found,
require calls the loader with two arguments:
-modname and an extra value dependent on how it got the loader.
-(If the loader came from a file,
-this extra value is the file name.)
+modname and an extra value,
+a loader data,
+also returned by the searcher.
+The loader data can be any value useful to the module;
+for the default searchers,
+it indicates where the loader was found.
+(For instance, if the loader came from a file,
+this extra value is the file path.)
If the loader returns any non-nil value,
require assigns the returned value to package.loaded[modname].
If the loader does not return a non-nil value and
has not assigned any value to package.loaded[modname],
then require assigns true to this entry.
In any case, require returns the
final value of package.loaded[modname].
+Besides that value, require also returns as a second result
+the loader data returned by the searcher,
+which indicates how require found the module.
If there is any error loading or running the module,
or if it cannot find any loader for the module,
then require raises an error.
package.configA string describing some compile-time configurations for packages. This string is a sequence of lines:
\' for Windows and '/' for all other systems.;'.?'.!'.luaopen_ function name.
Default is '-'.
package.cpath
-The path used by require to search for a C loader.
+A string with the path used by require
+to search for a C loader.
Lua initializes the C path package.cpath in the same way
it initializes the Lua path package.path,
-using the environment variable LUA_CPATH_5_3,
+using the environment variable LUA_CPATH_5_4,
or the environment variable LUA_CPATH,
or a default path defined in luaconf.h.
package.loaded
A table used by require to control which
modules are already loaded.
When you require a module modname and
package.loaded[modname] is not false,
require simply returns the value stored there.
This variable is only a reference to the real table;
assignments to this variable do not change the
table used by require.
package.loadlib (libname, funcname)
Dynamically links the host program with the C library libname.
If funcname is "*",
then it only links with the library,
making the symbols exported by the library
available to other dynamically linked libraries.
Otherwise,
it looks for a function funcname inside the library
and returns this function as a C function.
So, funcname must follow the lua_CFunction prototype
(see lua_CFunction).
This is a low-level function.
It completely bypasses the package and module system.
Unlike require,
it does not perform any path searching and
does not automatically adds extensions.
libname must be the complete file name of the C library,
including if necessary a path and an extension.
funcname must be the exact name exported by the C library
(which may depend on the C compiler and linker used).
This function is not supported by Standard C.
As such, it is only available on some platforms
(Windows, Linux, Mac OS X, Solaris, BSD,
plus other Unix systems that support the dlfcn standard).
+
+This function is inherently insecure,
+as it allows Lua to call any function in any readable dynamic
+library in the system.
+(Lua calls any function assuming the function
+has a proper prototype and respects a proper protocol
+(see lua_CFunction).
+Therefore,
+calling an arbitrary function in an arbitrary dynamic library
+more often than not results in an access violation.)
+
+
package.path
-The path used by require to search for a Lua loader.
+A string with the path used by require
+to search for a Lua loader.
At start-up, Lua initializes this variable with
-the value of the environment variable LUA_PATH_5_3 or
+the value of the environment variable LUA_PATH_5_4 or
the environment variable LUA_PATH or
with a default path defined in luaconf.h,
if those environment variables are not defined.
-Any ";;" in the value of the environment variable
+A ";;" in the value of the environment variable
is replaced by the default path.
package.preload
A table to store loaders for specific modules
(see require).
This variable is only a reference to the real table;
assignments to this variable do not change the
table used by require.
package.searchers
-A table used by require to control how to load modules.
+A table used by require to control how to find modules.
Each entry in this table is a searcher function.
When looking for a module,
require calls each of these searchers in ascending order,
with the module name (the argument given to require) as its
-sole parameter.
-The function can return another function (the module loader)
-plus an extra value that will be passed to that loader,
-or a string explaining why it did not find that module
+sole argument.
+If the searcher finds the module,
+it returns another function, the module loader,
+plus an extra value, a loader data,
+that will be passed to that loader and
+returned as a second result by require.
+If it cannot find the module,
+it returns a string explaining why
(or nil if it has nothing to say).
Lua initializes this table with four searcher functions.
The first searcher simply looks for a loader in the
package.preload table.
The second searcher looks for a loader as a Lua library,
using the path stored at package.path.
The search is done as described in function package.searchpath.
The third searcher looks for a loader as a C library,
using the path given by the variable package.cpath.
Again,
the search is done as described in function package.searchpath.
For instance,
if the C path is the string
"./?.so;./?.dll;/usr/local/?/init.so"
the searcher for module foo
will try to open the files ./foo.so, ./foo.dll,
and /usr/local/foo/init.so, in that order.
Once it finds a C library,
this searcher first uses a dynamic link facility to link the
application with the library.
Then it tries to find a C function inside the library to
be used as the loader.
The name of this C function is the string "luaopen_"
concatenated with a copy of the module name where each dot
is replaced by an underscore.
Moreover, if the module name has a hyphen,
its suffix after (and including) the first hyphen is removed.
For instance, if the module name is a.b.c-v2.1,
the function name will be luaopen_a_b_c.
The fourth searcher tries an all-in-one loader.
It searches the C path for a library for
the root name of the given module.
For instance, when requiring a.b.c,
it will search for a C library for a.
If found, it looks into it for an open function for
the submodule;
in our example, that would be luaopen_a_b_c.
With this facility, a package can pack several C submodules
into one single library,
with each submodule keeping its original open function.
All searchers except the first one (preload) return as the extra value
-the file name where the module was found,
+the file path where the module was found,
as returned by package.searchpath.
-The first searcher returns no extra value.
+The first searcher always returns the string ":preload:".
+
+
+
+Searchers should raise no errors and have no side effects in Lua. +(They may have side effects in C, +for instance by linking the application with a library.)
package.searchpath (name, path [, sep [, rep]])
Searches for the given name in the given path.
A path is a string containing a sequence of
templates separated by semicolons.
For each template,
the function replaces each interrogation mark (if any)
in the template with a copy of name
wherein all occurrences of sep
(a dot, by default)
were replaced by rep
(the system's directory separator, by default),
and then tries to open the resulting file name.
For instance, if the path is the string
"./?.lua;./?.lc;/usr/local/?/init.lua"
the search for the name foo.a
will try to open the files
./foo/a.lua, ./foo/a.lc, and
/usr/local/foo/a/init.lua, in that order.
Returns the resulting name of the first file that it can open in read mode (after closing the file), -or nil plus an error message if none succeeds. +or fail plus an error message if none succeeds. (This error message lists all file names it tried to open.)
This library provides generic functions for string manipulation, such as finding and extracting substrings, and pattern matching. When indexing a string in Lua, the first character is at position 1 (not at 0, as in C). Indices are allowed to be negative and are interpreted as indexing backwards, from the end of the string. Thus, the last character is at position -1, and so on.
The string library provides all its functions inside the table
string.
It also sets a metatable for strings
where the __index field points to the string table.
Therefore, you can use the string functions in object-oriented style.
For instance, string.byte(s,i)
can be written as s:byte(i).
The string library assumes one-byte character encodings.
string.byte (s [, i [, j]])s[i],
s[i+1], ..., s[j].
The default value for i is 1;
the default value for j is i.
These indices are corrected
following the same rules of function string.sub.
Numeric codes are not necessarily portable across platforms.
string.char (···)Numeric codes are not necessarily portable across platforms.
string.dump (function [, strip])
Returns a string containing a binary representation
(a binary chunk)
of the given function,
so that a later load on this string returns
a copy of the function (but with new upvalues).
If strip is a true value,
the binary representation may not include all debug information
about the function,
to save space.
Functions with upvalues have only their number of upvalues saved.
When (re)loaded,
-those upvalues receive fresh instances containing nil.
-(You can use the debug library to serialize
+those upvalues receive fresh instances.
+(See the load function for details about
+how these upvalues are initialized.
+You can use the debug library to serialize
and reload the upvalues of a function
in a way adequate to your needs.)
string.find (s, pattern [, init [, plain]])
Looks for the first match of
pattern (see §6.4.1) in the string s.
If it finds a match, then find returns the indices of s
where this occurrence starts and ends;
-otherwise, it returns nil.
+otherwise, it returns fail.
A third, optional numeric argument init specifies
where to start the search;
its default value is 1 and can be negative.
A value of true as a fourth, optional argument plain
turns off the pattern matching facilities,
so the function does a plain "find substring" operation,
with no characters in pattern being considered magic.
-Note that if plain is given, then init must be given as well.
If the pattern has captures, then in a successful match the captured values are also returned, after the two indices.
string.format (formatstring, ···)
Returns a formatted version of its variable number of arguments
-following the description given in its first argument (which must be a string).
+following the description given in its first argument,
+which must be a string.
The format string follows the same rules as the ISO C function sprintf.
-The only differences are that the options/modifiers
-*, h, L, l, n,
-and p are not supported
-and that there is an extra option, q.
+The only differences are that the conversion specifiers and modifiers
+*, h, L, l, and n are not supported
+and that there is an extra specifier, q.
-The q option formats a string between double quotes,
+The specifier q formats booleans, nil, numbers, and strings
+in a way that the result is a valid constant in Lua source code.
+Booleans and nil are written in the obvious way
+(true, false, nil).
+Floats are written in hexadecimal,
+to preserve full precision.
+A string is written between double quotes,
using escape sequences when necessary to ensure that
it can safely be read back by the Lua interpreter.
For instance, the call
string.format('%q', 'a string with "quotes" and \n new line')
may produce the string:
"a string with \"quotes\" and \
new line"
-
++This specifier does not support modifiers (flags, width, length). +
-Options
+The conversion specifiers
A, a, E, e, f,
G, and g all expect a number as argument.
-Options c, d,
+The specifiers c, d,
i, o, u, X, and x
expect an integer.
When Lua is compiled with a C89 compiler,
-options A and a (hexadecimal floats)
-do not support any modifier (flags, width, length).
+the specifiers A and a (hexadecimal floats)
+do not support modifiers.
-Option s expects a string;
+The specifier s expects a string;
if its argument is not a string,
it is converted to one following the same rules of tostring.
-If the option has any modifier (flags, width, length),
-the string argument should not contain embedded zeros.
+If the specifier has any modifier,
+the corresponding string argument should not contain embedded zeros.
+
+
+
+The specifier p formats the pointer
+returned by lua_topointer.
+That gives a unique string identifier for tables, userdata,
+threads, strings, and functions.
+For other values (numbers, nil, booleans),
+this specifier results in a string representing
+the pointer NULL.
-
string.gmatch (s, pattern)string.gmatch (s, pattern [, init])pattern (see §6.4.1)
over the string s.
If pattern specifies no captures,
then the whole match is produced in each call.
+A third, optional numeric argument init specifies
+where to start the search;
+its default value is 1 and can be negative.
As an example, the following loop
will iterate over all the words from string s,
printing one per line:
s = "hello world from Lua"
for w in string.gmatch(s, "%a+") do
print(w)
end
The next example collects all pairs key=value from the
given string into a table:
t = {}
s = "from=world, to=Lua"
for k, v in string.gmatch(s, "(%w+)=(%w+)") do
t[k] = v
end
For this function, a caret '^' at the start of a pattern does not
work as an anchor, as this would prevent the iteration.
string.gsub (s, pattern, repl [, n])s
in which all (or the first n, if given)
occurrences of the pattern (see §6.4.1) have been
replaced by a replacement string specified by repl,
which can be a string, a table, or a function.
gsub also returns, as its second value,
the total number of matches that occurred.
The name gsub comes from Global SUBstitution.
If repl is a string, then its value is used for replacement.
The character % works as an escape character:
any sequence in repl of the form %d,
with d between 1 and 9,
-stands for the value of the d-th captured substring.
-The sequence %0 stands for the whole match.
-The sequence %% stands for a single %.
+stands for the value of the d-th captured substring;
+the sequence %0 stands for the whole match;
+the sequence %% stands for a single %.
If repl is a table, then the table is queried for every match,
using the first capture as the key.
If repl is a function, then this function is called every time a
match occurs, with all captured substrings passed as arguments,
in order.
In any case, if the pattern specifies no captures, then it behaves as if the whole pattern was inside a capture.
If the value returned by the table query or by the function call is a string or a number, then it is used as the replacement string; otherwise, if it is false or nil, then there is no replacement (that is, the original match is kept in the string).
Here are some examples:
x = string.gsub("hello world", "(%w+)", "%1 %1")
--> x="hello hello world world"
x = string.gsub("hello world", "%w+", "%0 %0", 1)
--> x="hello hello world"
x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1")
--> x="world hello Lua from"
x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv)
--> x="home = /home/roberto, user = roberto"
x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s)
return load(s)()
end)
--> x="4+5 = 9"
- local t = {name="lua", version="5.3"}
+ local t = {name="lua", version="5.4"}
x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t)
- --> x="lua-5.3.tar.gz"
+ --> x="lua-5.4.tar.gz"
string.len (s)
Receives a string and returns its length.
The empty string "" has length 0.
Embedded zeros are counted,
so "a\000bc\000" has length 5.
string.lower (s)Receives a string and returns a copy of this string with all uppercase letters changed to lowercase. All other characters are left unchanged. The definition of what an uppercase letter is depends on the current locale.
string.match (s, pattern [, init])
Looks for the first match of
-pattern (see §6.4.1) in the string s.
+the pattern (see §6.4.1) in the string s.
If it finds one, then match returns
the captures from the pattern;
-otherwise it returns nil.
+otherwise it returns fail.
If pattern specifies no captures,
then the whole match is returned.
A third, optional numeric argument init specifies
where to start the search;
its default value is 1 and can be negative.
string.pack (fmt, v1, v2, ···)
Returns a binary string containing the values v1, v2, etc.
-packed (that is, serialized in binary form)
+serialized in binary form (packed)
according to the format string fmt (see §6.4.2).
string.packsize (fmt)
Returns the size of a string resulting from string.pack
with the given format.
The format string cannot have the variable-length options
's' or 'z' (see §6.4.2).
string.rep (s, n [, sep])
Returns a string that is the concatenation of n copies of
the string s separated by the string sep.
The default value for sep is the empty string
(that is, no separator).
Returns the empty string if n is not positive.
(Note that it is very easy to exhaust the memory of your machine with a single call to this function.)
string.reverse (s)
Returns a string that is the string s reversed.
string.sub (s, i [, j])
Returns the substring of s that
starts at i and continues until j;
i and j can be negative.
If j is absent, then it is assumed to be equal to -1
(which is the same as the string length).
In particular,
the call string.sub(s,1,j) returns a prefix of s
with length j,
and string.sub(s, -i) (for a positive i)
returns a suffix of s
with length i.
If, after the translation of negative indices,
i is less than 1,
it is corrected to 1.
If j is greater than the string length,
it is corrected to that length.
If, after these corrections,
i is greater than j,
the function returns the empty string.
string.unpack (fmt, s [, pos])
Returns the values packed in string s (see string.pack)
according to the format string fmt (see §6.4.2).
An optional pos marks where
to start reading in s (default is 1).
After the read values,
this function also returns the index of the first unread byte in s.
string.upper (s)Receives a string and returns a copy of this string with all lowercase letters changed to uppercase. All other characters are left unchanged. The definition of what a lowercase letter is depends on the current locale. + +
Patterns in Lua are described by regular strings,
which are interpreted as patterns by the pattern-matching functions
string.find,
string.gmatch,
string.gsub,
and string.match.
This section describes the syntax and the meaning
(that is, what they match) of these strings.
+
+
A character class is used to represent a set of characters. The following combinations are allowed in describing a character class:
^$()%.[]*+-?)
represents the character x itself.
.: (a dot) represents all characters.%a: represents all letters.%c: represents all control characters.%d: represents all digits.%g: represents all printable characters except space.%l: represents all lowercase letters.%p: represents all punctuation characters.%s: represents all space characters.%u: represents all uppercase letters.%w: represents all alphanumeric characters.%x: represents all hexadecimal digits.%x: (where x is any non-alphanumeric character)
represents the character x.
This is the standard way to escape the magic characters.
Any non-alphanumeric character
(including all punctuation characters, even the non-magical)
-can be preceded by a '%'
-when used to represent itself in a pattern.
+can be preceded by a '%' to represent itself in a pattern.
[set]:
represents the class which is the union of all
characters in set.
A range of characters can be specified by
separating the end characters of the range,
in ascending order, with a '-'.
All classes %x described above can also be used as
components in set.
All other characters in set represent themselves.
For example, [%w_] (or [_%w])
represents all alphanumeric characters plus the underscore,
[0-7] represents the octal digits,
and [0-7%l%-] represents the octal digits plus
the lowercase letters plus the '-' character.
You can put a closing square bracket in a set by positioning it as the first character in the set. You can put a hyphen in a set by positioning it as the first or the last character in the set. (You can also use an escape for both cases.)
The interaction between ranges and classes is not defined.
Therefore, patterns like [%a-z] or [a-%%]
have no meaning.
[^set]:
represents the complement of set,
where set is interpreted as above.
For all classes represented by single letters (%a, %c, etc.),
the corresponding uppercase letter represents the complement of the class.
For instance, %S represents all non-space characters.
The definitions of letter, space, and other character groups
depend on the current locale.
In particular, the class [a-z] may not be equivalent to %l.
A pattern item can be
*',
-which matches zero or more repetitions of characters in the class.
+which matches sequences of zero or more characters in the class.
These repetition items will always match the longest possible sequence;
+',
-which matches one or more repetitions of characters in the class.
+which matches sequences of one or more characters in the class.
These repetition items will always match the longest possible sequence;
-',
-which also matches zero or more repetitions of characters in the class.
+which also matches sequences of zero or more characters in the class.
Unlike '*',
these repetition items will always match the shortest possible sequence;
?',
which matches zero or one occurrence of a character in the class.
It always matches one occurrence if possible;
%n, for n between 1 and 9;
such item matches a substring equal to the n-th captured string
(see below);
%bxy, where x and y are two distinct characters;
such item matches strings that start with x, end with y,
and where the x and y are balanced.
This means that, if one reads the string from left to right,
counting +1 for an x and -1 for a y,
the ending y is the first y where the count reaches 0.
For instance, the item %b() matches expressions with
balanced parentheses.
%f[set], a frontier pattern;
such item matches an empty string at any position such that
the next character belongs to set
and the previous character does not belong to set.
The set set is interpreted as previously described.
The beginning and the end of the subject are handled as if
they were the character '\0'.
A pattern is a sequence of pattern items.
A caret '^' at the beginning of a pattern anchors the match at the
beginning of the subject string.
A '$' at the end of a pattern anchors the match at the
end of the subject string.
At other positions,
'^' and '$' have no special meaning and represent themselves.
A pattern can contain sub-patterns enclosed in parentheses;
they describe captures.
When a match succeeds, the substrings of the subject string
that match captures are stored (captured) for future use.
Captures are numbered according to their left parentheses.
For instance, in the pattern "(a*(.)%w(%s*))",
the part of the string matching "a*(.)%w(%s*)" is
-stored as the first capture (and therefore has number 1);
+stored as the first capture, and therefore has number 1;
the character matching "." is captured with number 2,
and the part matching "%s*" has number 3.
-As a special case, the empty capture () captures
+As a special case, the capture () captures
the current string position (a number).
For instance, if we apply the pattern "()aa()" on the
string "flaaap", there will be two captures: 3 and 5.
+
+The function string.gsub and the iterator string.gmatch
+match multiple occurrences of the given pattern in the subject.
+For these functions,
+a new match is considered valid only
+if it ends at least one byte after the end of the previous match.
+In other words, the pattern machine never accepts the
+empty string as a match immediately after another match.
+As an example,
+consider the results of the following code:
+
+
+ > string.gsub("abc", "()a*()", print);
+ --> 1 2
+ --> 3 3
+ --> 4 4
+
+The second and third results come from Lua matching an empty
+string after 'b' and another one after 'c'.
+Lua does not match an empty string after 'a',
+because it would end at the same position of the previous match.
+
+
+
+
+
The first argument to string.pack,
string.packsize, and string.unpack
is a format string,
which describes the layout of the structure being created or read.
A format string is a sequence of conversion options. The conversion options are as follows:
<: sets little endian>: sets big endian=: sets native endian![n]: sets maximum alignment to n
(default is native alignment)b: a signed byte (char)B: an unsigned byte (char)h: a signed short (native size)H: an unsigned short (native size)l: a signed long (native size)L: an unsigned long (native size)j: a lua_IntegerJ: a lua_UnsignedT: a size_t (native size)i[n]: a signed int with n bytes
(default is native size)I[n]: an unsigned int with n bytes
(default is native size)f: a float (native size)d: a double (native size)n: a lua_Numbercn: a fixed-sized string with n bytesz: a zero-terminated strings[n]: a string preceded by its length
coded as an unsigned integer with n bytes
(default is a size_t)x: one byte of paddingXop: an empty item that aligns
according to option op
(which is otherwise ignored) ': (empty space) ignored ': (space) ignored
(A "[n]" means an optional integral numeral.)
Except for padding, spaces, and configurations
(options "xX <=>!"),
-each option corresponds to an argument (in string.pack)
-or a result (in string.unpack).
+each option corresponds to an argument in string.pack
+or a result in string.unpack.
For options "!n", "sn", "in", and "In",
n can be any integer between 1 and 16.
All integral options check overflows;
string.pack checks whether the given value fits in the given size;
string.unpack checks whether the read value fits in a Lua integer.
+For the unsigned options,
+Lua integers are treated as unsigned values too.
Any format string starts as if prefixed by "!1=",
that is,
with maximum alignment of 1 (no alignment)
and native endianness.
+
+Native endianness assumes that the whole system is +either big or little endian. +The packing functions will not emulate correctly the behavior +of mixed-endian formats. + +
Alignment works as follows:
For each option,
the format gets extra padding until the data starts
at an offset that is a multiple of the minimum between the
option size and the maximum alignment;
this minimum must be a power of 2.
Options "c" and "z" are not aligned;
option "s" follows the alignment of its starting integer.
All padding is filled with zeros by string.pack
-(and ignored by string.unpack).
+and ignored by string.unpack.
This library provides basic support for UTF-8 encoding.
It provides all its functions inside the table utf8.
This library does not provide any support for Unicode other
than the handling of the encoding.
Any operation that needs the meaning of a character,
such as character classification, is outside its scope.
Unless stated otherwise, all functions that expect a byte position as a parameter assume that the given position is either the start of a byte sequence or one plus the length of the subject string. As in the string library, negative indices count from the end of the string. +
+Functions that create byte sequences
+accept all values up to 0x7FFFFFFF,
+as defined in the original UTF-8 specification;
+that implies byte sequences of up to six bytes.
+
+
+
+Functions that interpret byte sequences only accept
+valid sequences (well formed and not overlong).
+By default, they only accept byte sequences
+that result in valid Unicode code points,
+rejecting values greater than 10FFFF and surrogates.
+A boolean argument lax, when available,
+lifts these checks,
+so that all values up to 0x7FFFFFFF are accepted.
+(Not well formed and overlong sequences are still rejected.)
+
+
utf8.char (···)Receives zero or more integers, converts each one to its corresponding UTF-8 byte sequence and returns a string with the concatenation of all these sequences.
utf8.charpattern[\0-\x7F\xC2-\xF4][\x80-\xBF]*"
+
+
+
+The pattern (a string, not a function) "[\0-\x7F\xC2-\xFD][\x80-\xBF]*"
(see §6.4.1),
which matches exactly one UTF-8 byte sequence,
assuming that the subject is a valid UTF-8 string.
-
utf8.codes (s)utf8.codes (s [, lax])Returns values so that the construction
for p, c in utf8.codes(s) do body end
-will iterate over all characters in string s,
+will iterate over all UTF-8 characters in string s,
with p being the position (in bytes) and c the code point
of each character.
It raises an error if it meets any invalid byte sequence.
-
utf8.codepoint (s [, i [, j]])s
+utf8.codepoint (s [, i [, j [, lax]]])
+Returns the code points (as integers) from all characters in s
that start between byte position i and j (both included).
The default for i is 1 and for j is i.
It raises an error if it meets any invalid byte sequence.
-
utf8.len (s [, i [, j]])utf8.len (s [, i [, j [, lax]]])
Returns the number of UTF-8 characters in string s
that start between positions i and j (both inclusive).
The default for i is 1 and for j is -1.
If it finds any invalid byte sequence,
-returns a false value plus the position of the first invalid byte.
+returns fail plus the position of the first invalid byte.
utf8.offset (s, n [, i])
Returns the position (in bytes) where the encoding of the
n-th character of s
(counting from position i) starts.
A negative n gets characters before position i.
The default for i is 1 when n is non-negative
and #s + 1 otherwise,
so that utf8.offset(s, -n) gets the offset of the
n-th character from the end of the string.
If the specified character is neither in the subject
nor right after its end,
-the function returns nil.
+the function returns fail.
As a special case,
when n is 0 the function returns the start of the encoding
of the character that contains the i-th byte of s.
This function assumes that s is a valid UTF-8 string.
This library provides generic functions for table manipulation.
It provides all its functions inside the table table.
Remember that, whenever an operation needs the length of a table, all caveats about the length operator apply (see §3.4.7). All functions ignore non-numeric keys in the tables given as arguments.
table.concat (list [, sep [, i [, j]]])
Given a list where all elements are strings or numbers,
returns the string list[i]..sep..list[i+1] ··· sep..list[j].
The default value for sep is the empty string,
the default for i is 1,
and the default for j is #list.
If i is greater than j, returns the empty string.
table.insert (list, [pos,] value)
Inserts element value at position pos in list,
shifting up the elements
list[pos], list[pos+1], ···, list[#list].
The default value for pos is #list+1,
so that a call table.insert(t,x) inserts x at the end
-of list t.
+of the list t.
table.move (a1, f, e, t [,a2])
-Moves elements from table a1 to table a2,
+Moves elements from the table a1 to the table a2,
performing the equivalent to the following
multiple assignment:
a2[t],··· = a1[f],···,a1[e].
The default for a2 is a1.
The destination range can overlap with the source range.
The number of elements to be moved must fit in a Lua integer.
Returns the destination table a2.
table.pack (···)
Returns a new table with all arguments stored into keys 1, 2, etc.
and with a field "n" with the total number of arguments.
-Note that the resulting table may not be a sequence.
+Note that the resulting table may not be a sequence,
+if some arguments are nil.
table.remove (list [, pos])
Removes from list the element at position pos,
returning the value of the removed element.
When pos is an integer between 1 and #list,
it shifts down the elements
list[pos+1], list[pos+2], ···, list[#list]
and erases element list[#list];
The index pos can also be 0 when #list is 0,
-or #list + 1;
-in those cases, the function erases the element list[pos].
+or #list + 1.
The default value for pos is #list,
so that a call table.remove(l) removes the last element
-of list l.
+of the list l.
table.sort (list [, comp])
-Sorts list elements in a given order, in-place,
+Sorts the list elements in a given order, in-place,
from list[1] to list[#list].
If comp is given,
then it must be a function that receives two list elements
and returns true when the first element must come
before the second in the final order
(so that, after the sort,
i < j implies not comp(list[j],list[i])).
If comp is not given,
then the standard Lua operator < is used instead.
Note that the comp function must define
a strict partial order over the elements in the list;
that is, it must be asymmetric and transitive.
Otherwise, no valid sort may be possible.
The sort algorithm is not stable: elements considered equal by the given order may have their relative positions changed by the sort.
table.unpack (list [, i [, j]])Returns the elements from the given list. This function is equivalent to
return list[i], list[i+1], ···, list[j]
By default, i is 1 and j is #list.
This library provides basic mathematical functions.
It provides all its functions and constants inside the table math.
Functions with the annotation "integer/float" give
integer results for integer arguments
-and float results for float (or mixed) arguments.
-Rounding functions
-(math.ceil, math.floor, and math.modf)
+and float results for non-integer arguments.
+The rounding functions
+math.ceil, math.floor, and math.modf
return an integer when the result fits in the range of an integer,
or a float otherwise.
math.abs (x)
-Returns the absolute value of x. (integer/float)
+Returns the maximum value between x and -x. (integer/float)
math.acos (x)
Returns the arc cosine of x (in radians).
math.asin (x)
Returns the arc sine of x (in radians).
math.atan (y [, x])
Returns the arc tangent of y/x (in radians),
but uses the signs of both arguments to find the
quadrant of the result.
-(It also handles correctly the case of x being zero.)
+It also handles correctly the case of x being zero.
The default value for x is 1,
so that the call math.atan(y)
returns the arc tangent of y.
math.ceil (x)
-Returns the smallest integral value larger than or equal to x.
+Returns the smallest integral value greater than or equal to x.
math.cos (x)
Returns the cosine of x (assumed to be in radians).
math.deg (x)
Converts the angle x from radians to degrees.
math.exp (x)
Returns the value ex
(where e is the base of natural logarithms).
math.floor (x)
-Returns the largest integral value smaller than or equal to x.
+Returns the largest integral value less than or equal to x.
math.fmod (x, y)
Returns the remainder of the division of x by y
that rounds the quotient towards zero. (integer/float)
math.huge
The float value HUGE_VAL,
-a value larger than any other numeric value.
+a value greater than any other numeric value.
math.log (x [, base])
Returns the logarithm of x in the given base.
The default for base is e
(so that the function returns the natural logarithm of x).
math.max (x, ···)
Returns the argument with the maximum value,
-according to the Lua operator <. (integer/float)
+according to the Lua operator <.
math.maxinteger
math.min (x, ···)
Returns the argument with the minimum value,
-according to the Lua operator <. (integer/float)
+according to the Lua operator <.
math.mininteger
math.modf (x)
Returns the integral part of x and the fractional part of x.
Its second result is always a float.
math.piThe value of π.
math.rad (x)
Converts the angle x from degrees to radians.
math.random ([m [, n]])
When called without arguments,
returns a pseudo-random float with uniform distribution
in the range [0,1).
When called with two integers m and n,
math.random returns a pseudo-random integer
with uniform distribution in the range [m, n].
-(The value n-m cannot be negative and must fit in a Lua integer.)
-The call math.random(n) is equivalent to math.random(1,n).
+The call math.random(n), for a positive n,
+is equivalent to math.random(1,n).
+The call math.random(0) produces an integer with
+all bits (pseudo)random.
+
+
+
+This function uses the xoshiro256** algorithm to produce
+pseudo-random 64-bit integers,
+which are the results of calls with argument 0.
+Other results (ranges and floats)
+are unbiased extracted from these integers.
-This function is an interface to the underling
-pseudo-random generator function provided by C.
+Lua initializes its pseudo-random generator with the equivalent of
+a call to math.randomseed with no arguments,
+so that math.random should generate
+different sequences of results each time the program runs.
-
math.randomseed (x)math.randomseed ([x [, y]])
-Sets x as the "seed"
-for the pseudo-random generator:
+When called with at least one argument,
+the integer parameters x and y are
+joined into a 128-bit seed that
+is used to reinitialize the pseudo-random generator;
equal seeds produce equal sequences of numbers.
+The default for y is zero.
+
+
+
+When called with no arguments, +Lua generates a seed with +a weak attempt for randomness. + + +
+This function returns the two seed components +that were effectively used, +so that setting them again repeats the sequence. + + +
+To ensure a required level of randomness to the initial state
+(or contrarily, to have a deterministic sequence,
+for instance when debugging a program),
+you should call math.randomseed with explicit arguments.
math.sin (x)
Returns the sine of x (assumed to be in radians).
math.sqrt (x)
Returns the square root of x.
(You can also use the expression x^0.5 to compute this value.)
math.tan (x)
Returns the tangent of x (assumed to be in radians).
math.tointeger (x)
If the value x is convertible to an integer,
returns that integer.
-Otherwise, returns nil.
+Otherwise, returns fail.
math.type (x)
Returns "integer" if x is an integer,
"float" if it is a float,
-or nil if x is not a number.
+or fail if x is not a number.
math.ult (m, n)
Returns a boolean,
true if and only if integer m is below integer n when
they are compared as unsigned integers.
The I/O library provides two different styles for file manipulation. The first one uses implicit file handles; that is, there are operations to set a default input file and a default output file, -and all input/output operations are over these default files. +and all input/output operations are done over these default files. The second style uses explicit file handles.
When using implicit file handles,
all operations are supplied by table io.
When using explicit file handles,
the operation io.open returns a file handle
and then all operations are supplied as methods of the file handle.
+
+The metatable for file handles provides metamethods
+for __gc and __close that try
+to close the file when called.
+
+
The table io also provides
three predefined file handles with their usual meanings from C:
io.stdin, io.stdout, and io.stderr.
The I/O library never closes these files.
Unless otherwise stated,
-all I/O functions return nil on failure
-(plus an error message as a second result and
-a system-dependent error code as a third result)
-and some value different from nil on success.
-In non-POSIX systems,
+all I/O functions return fail on failure,
+plus an error message as a second result and
+a system-dependent error code as a third result,
+and some non-false value on success.
+On non-POSIX systems,
the computation of the error message and error code
in case of errors
may be not thread safe,
because they rely on the global C variable errno.
io.close ([file])
Equivalent to file:close().
Without a file, closes the default output file.
io.flush ()
Equivalent to io.output():flush().
io.input ([file])When called with a file name, it opens the named file (in text mode), and sets its handle as the default input file. When called with a file handle, it simply sets this file handle as the default input file. When called without arguments, it returns the current default input file.
In case of errors this function raises the error, instead of returning an error code.
io.lines ([filename, ···])
Opens the given file name in read mode
and returns an iterator function that
works like file:lines(···) over the opened file.
-When the iterator function detects the end of file,
-it returns no values (to finish the loop) and automatically closes the file.
+When the iterator function fails to read any value,
+it automatically closes the file.
+Besides the iterator function,
+io.lines returns three other values:
+two nil values as placeholders,
+plus the created file handle.
+Therefore, when used in a generic for loop,
+the file is closed also if the loop is interrupted by an
+error or a break.
The call io.lines() (with no file name) is equivalent
-to io.input():lines("*l");
+to io.input():lines("l");
that is, it iterates over the lines of the default input file.
In this case, the iterator does not close the file when the loop ends.
-In case of errors this function raises the error, +In case of errors opening the file, +this function raises the error, instead of returning an error code.
io.open (filename [, mode])
This function opens a file,
in the mode specified in the string mode.
In case of success,
it returns a new file handle.
The mode string can be any of the following:
r": read mode (the default);w": write mode;a": append mode;r+": update mode, all previous data is preserved;w+": update mode, all previous data is erased;a+": append update mode, previous data is preserved,
writing is only allowed at the end of file.
The mode string can also have a 'b' at the end,
which is needed in some systems to open the file in binary mode.
io.output ([file])
Similar to io.input, but operates over the default output file.
io.popen (prog [, mode])This function is system dependent and is not available on all platforms.
-Starts program prog in a separated process and returns
+Starts the program prog in a separated process and returns
a file handle that you can use to read data from this program
(if mode is "r", the default)
or to write data to this program
(if mode is "w").
io.read (···)
Equivalent to io.input():read(···).
io.tmpfile ()In case of success, returns a handle for a temporary file. This file is opened in update mode and it is automatically removed when the program ends.
io.type (obj)
Checks whether obj is a valid file handle.
Returns the string "file" if obj is an open file handle,
"closed file" if obj is a closed file handle,
-or nil if obj is not a file handle.
+or fail if obj is not a file handle.
io.write (···)
Equivalent to io.output():write(···).
file:close ()
Closes file.
Note that files are automatically closed when
their handles are garbage collected,
but that takes an unpredictable amount of time to happen.
When closing a file handle created with io.popen,
file:close returns the same values
returned by os.execute.
file:flush ()
Saves any written data to file.
file:lines (···)
Returns an iterator function that,
each time it is called,
reads the file according to the given formats.
When no format is given,
uses "l" as a default.
As an example, the construction
for c in file:lines(1) do body end
will iterate over all characters of the file,
starting at the current position.
Unlike io.lines, this function does not close the file
when the loop ends.
-
-In case of errors this function raises the error, -instead of returning an error code. - -
file:read (···)
Reads the file file,
according to the given formats, which specify what to read.
For each format,
the function returns a string or a number with the characters read,
-or nil if it cannot read data with the specified format.
+or fail if it cannot read data with the specified format.
(In this latter case,
the function does not read subsequent formats.)
-When called without formats,
+When called without arguments,
it uses a default format that reads the next line
(see below).
The available formats are
n":
reads a numeral and returns it as a float or an integer,
following the lexical conventions of Lua.
-(The numeral may have leading spaces and a sign.)
+(The numeral may have leading whitespaces and a sign.)
This format always reads the longest input sequence that
is a valid prefix for a numeral;
if that prefix does not form a valid numeral
-(e.g., an empty string, "0x", or "3.4e-"),
-it is discarded and the function returns nil.
+(e.g., an empty string, "0x", or "3.4e-")
+or it is too long (more than 200 characters),
+it is discarded and the format returns fail.
a":
reads the whole file, starting at the current position.
-On end of file, it returns the empty string.
+On end of file, it returns the empty string;
+this format never fails.
l":
reads the next line skipping the end of line,
-returning nil on end of file.
+returning fail on end of file.
This is the default format.
L":
reads the next line keeping the end-of-line character (if present),
-returning nil on end of file.
+returning fail on end of file.
number is zero,
it reads nothing and returns an empty string,
-or nil on end of file.
+or fail on end of file.
The formats "l" and "L" should be used only for text files.
file:seek ([whence [, offset]])
Sets and gets the file position,
measured from the beginning of the file,
to the position given by offset plus a base
specified by the string whence, as follows:
set": base is position 0 (beginning of the file);cur": base is current position;end": base is end of file;
In case of success, seek returns the final file position,
measured in bytes from the beginning of the file.
-If seek fails, it returns nil,
+If seek fails, it returns fail,
plus a string describing the error.
The default value for whence is "cur",
and for offset is 0.
Therefore, the call file:seek() returns the current
file position, without changing it;
the call file:seek("set") sets the position to the
beginning of the file (and returns 0);
and the call file:seek("end") sets the position to the
end of the file, and returns its size.
file:setvbuf (mode [, size])-Sets the buffering mode for an output file. +Sets the buffering mode for a file. There are three available modes:
no": no buffering.full": full buffering.line": line buffering.no":
-no buffering; the result of any output operation appears immediately.
-full":
-full buffering; output operation is performed only
-when the buffer is full or when
-you explicitly flush the file (see io.flush).
-
+For the last two cases,
+size is a hint for the size of the buffer, in bytes.
+The default is an appropriate size.
-
line":
-line buffering; output is buffered until a newline is output
-or there is any input from some special files
-(such as a terminal device).
-
-For the last two cases, size
-specifies the size of the buffer, in bytes.
-The default is an appropriate size.
+
+The specific behavior of each mode is non portable;
+check the underlying ISO C function setvbuf in your platform for
+more details.
file:write (···)
Writes the value of each of its arguments to file.
The arguments must be strings or numbers.
In case of success, this function returns file.
-Otherwise it returns nil plus a string describing the error.
This library is implemented through table os.
os.clock ()
Returns an approximation of the amount in seconds of CPU time
-used by the program.
+used by the program,
+as returned by the underlying ISO C function clock.
os.date ([format [, time]])
Returns a string or a table containing date and time,
formatted according to the given string format.
If the time argument is present,
this is the time to be formatted
(see the os.time function for a description of this value).
Otherwise, date formats the current time.
If format starts with '!',
then the date is formatted in Coordinated Universal Time.
After this optional character,
if format is the string "*t",
then date returns a table with the following fields:
year, month (1–12), day (1–31),
-hour (0–23), min (0–59), sec (0–61),
+hour (0–23), min (0–59),
+sec (0–61, due to leap seconds),
wday (weekday, 1–7, Sunday is 1),
yday (day of the year, 1–366),
and isdst (daylight saving flag, a boolean).
This last field may be absent
if the information is not available.
If format is not "*t",
then date returns the date as a string,
formatted according to the same rules as the ISO C function strftime.
-When called without arguments,
-date returns a reasonable date and time representation that depends on
-the host system and on the current locale.
-(More specifically, os.date() is equivalent to os.date("%c").)
+If format is absent, it defaults to "%c",
+which gives a human-readable date and time representation
+using the current locale.
-In non-POSIX systems,
+On non-POSIX systems,
this function may be not thread safe
because of its reliance on C function gmtime and C function localtime.
os.difftime (t2, t1)
Returns the difference, in seconds,
from time t1 to time t2
(where the times are values returned by os.time).
In POSIX, Windows, and some other systems,
this value is exactly t2-t1.
os.execute ([command])
This function is equivalent to the ISO C function system.
It passes command to be executed by an operating system shell.
Its first result is true
if the command terminated successfully,
-or nil otherwise.
+or fail otherwise.
After this first result
the function returns a string plus a number,
as follows:
exit":
the command terminated normally;
the following number is the exit status of the command.
signal":
the command was terminated by a signal;
the following number is the signal that terminated the command.
When called without a command,
os.execute returns a boolean that is true if a shell is available.
os.exit ([code [, close]])
Calls the ISO C function exit to terminate the host program.
If code is true,
the returned status is EXIT_SUCCESS;
if code is false,
the returned status is EXIT_FAILURE;
if code is a number,
the returned status is this number.
The default value for code is true.
If the optional second argument close is true,
closes the Lua state before exiting.
os.getenv (varname)
-Returns the value of the process environment variable varname,
-or nil if the variable is not defined.
+Returns the value of the process environment variable varname
+or fail if the variable is not defined.
os.remove (filename)Deletes the file (or empty directory, on POSIX systems) with the given name. -If this function fails, it returns nil, +If this function fails, it returns fail plus a string describing the error and the error code. Otherwise, it returns true.
os.rename (oldname, newname)
Renames the file or directory named oldname to newname.
-If this function fails, it returns nil,
+If this function fails, it returns fail,
plus a string describing the error and the error code.
Otherwise, it returns true.
os.setlocale (locale [, category])
Sets the current locale of the program.
locale is a system-dependent string specifying a locale;
category is an optional string describing which category to change:
"all", "collate", "ctype",
"monetary", "numeric", or "time";
the default category is "all".
The function returns the name of the new locale,
-or nil if the request cannot be honored.
+or fail if the request cannot be honored.
If locale is the empty string,
the current locale is set to an implementation-defined native locale.
If locale is the string "C",
the current locale is set to the standard C locale.
When called with nil as the first argument, this function only returns the name of the current locale for the given category.
This function may be not thread safe
because of its reliance on C function setlocale.
os.time ([table])
Returns the current time when called without arguments,
or a time representing the local date and time specified by the given table.
This table must have fields year, month, and day,
and may have fields
hour (default is 12),
min (default is 0),
sec (default is 0),
and isdst (default is nil).
Other fields are ignored.
For a description of these fields, see the os.date function.
-The values in these fields do not need to be inside their valid ranges.
+When the function is called,
+the values in these fields do not need to be inside their valid ranges.
For instance, if sec is -10,
-it means -10 seconds from the time specified by the other fields;
+it means 10 seconds before the time specified by the other fields;
if hour is 1000,
-it means +1000 hours from the time specified by the other fields.
+it means 1000 hours after the time specified by the other fields.
The returned value is a number, whose meaning depends on your system.
In POSIX, Windows, and some other systems,
this number counts the number
of seconds since some given start time (the "epoch").
In other systems, the meaning is not specified,
and the number returned by time can be used only as an argument to
os.date and os.difftime.
+
+When called with a table,
+os.time also normalizes all the fields
+documented in the os.date function,
+so that they represent the same time as before the call
+but with values inside their valid ranges.
+
+
os.tmpname ()Returns a string with a file name that can be used for a temporary file. The file must be explicitly opened before its use and explicitly removed when no longer needed.
In POSIX systems, this function also creates a file with that name, to avoid security risks. (Someone else might create the file with wrong permissions in the time between getting the name and creating the file.) You still have to open the file to use it and to remove it (even if you do not use it).
When possible,
you may prefer to use io.tmpfile,
which automatically removes the file when the program ends.
This library provides -the functionality of the debug interface (§4.9) to Lua programs. +the functionality of the debug interface (§4.7) to Lua programs. You should exert care when using this library. Several of its functions violate basic assumptions about Lua code (e.g., that variables local to a function cannot be accessed from outside; that userdata metatables cannot be changed by Lua code; that Lua programs do not crash) and therefore can compromise otherwise secure code. Moreover, some functions in this library may be slow.
All functions in this library are provided
inside the debug table.
All functions that operate over a thread
have an optional first argument which is the
thread to operate over.
The default is always the current thread.
debug.debug ()
Enters an interactive mode with the user,
running each string that the user enters.
Using simple commands and other debug facilities,
the user can inspect global and local variables,
change their values, evaluate expressions, and so on.
A line containing only the word cont finishes this function,
so that the caller continues its execution.
Note that commands for debug.debug are not lexically nested
within any function and so have no direct access to local variables.
debug.gethook ([thread])
Returns the current hook settings of the thread, as three values:
the current hook function, the current hook mask,
-and the current hook count
-(as set by the debug.sethook function).
+and the current hook count,
+as set by the debug.sethook function.
+
+
+
+Returns fail if there is no active hook.
debug.getinfo ([thread,] f [, what])
Returns a table with information about a function.
You can give the function directly
or you can give a number as the value of f,
which means the function running at level f of the call stack
of the given thread:
level 0 is the current function (getinfo itself);
level 1 is the function that called getinfo
-(except for tail calls, which do not count on the stack);
+(except for tail calls, which do not count in the stack);
and so on.
-If f is a number larger than the number of active functions,
-then getinfo returns nil.
+If f is a number greater than the number of active functions,
+then getinfo returns fail.
The returned table can contain all the fields returned by lua_getinfo,
with the string what describing which fields to fill in.
The default for what is to get all information available,
except the table of valid lines.
If present,
the option 'f'
adds a field named func with the function itself.
If present,
the option 'L'
adds a field named activelines with the table of
valid lines.
For instance, the expression debug.getinfo(1,"n").name returns
a name for the current function,
if a reasonable name can be found,
and the expression debug.getinfo(print)
returns a table with all available information
about the print function.
debug.getlocal ([thread,] f, local)
This function returns the name and the value of the local variable
with index local of the function at level f of the stack.
This function accesses not only explicit local variables,
-but also parameters, temporaries, etc.
+but also parameters and temporary values.
The first parameter or local variable has index 1, and so on,
following the order that they are declared in the code,
counting only the variables that are active
in the current scope of the function.
+Compile-time constants may not appear in this listing,
+if they were optimized away by the compiler.
Negative indices refer to vararg arguments;
-1 is the first vararg argument.
-The function returns nil if there is no variable with the given index,
+The function returns fail
+if there is no variable with the given index,
and raises an error when called with a level out of range.
(You can call debug.getinfo to check whether the level is valid.)
Variable names starting with '(' (open parenthesis)
represent variables with no known names
(internal variables such as loop control variables,
and variables from chunks saved without debug information).
The parameter f may also be a function.
In that case, getlocal returns only the name of function parameters.
debug.getmetatable (value)
Returns the metatable of the given value
or nil if it does not have a metatable.
debug.getregistry ()-Returns the registry table (see §4.5). +Returns the registry table (see §4.3).
debug.getupvalue (f, up)
This function returns the name and the value of the upvalue
with index up of the function f.
-The function returns nil if there is no upvalue with the given index.
+The function returns fail
+if there is no upvalue with the given index.
-Variable names starting with '(' (open parenthesis)
-represent variables with no known names
+(For Lua functions,
+upvalues are the external local variables that the function uses,
+and that are consequently included in its closure.)
+
+
+
+For C functions, this function uses the empty string ""
+as a name for all upvalues.
+
+
+
+Variable name '?' (interrogation mark)
+represents variables with no known names
(variables from chunks saved without debug information).
-
debug.getuservalue (u)debug.getuservalue (u, n)
-Returns the Lua value associated to u.
-If u is not a full userdata,
-returns nil.
+Returns the n-th user value associated
+to the userdata u plus a boolean,
+false if the userdata does not have that value.
debug.sethook ([thread,] hook, mask [, count])
-Sets the given function as a hook.
+Sets the given function as the debug hook.
The string mask and the number count describe
when the hook will be called.
The string mask may have any combination of the following characters,
with the given meaning:
c': the hook is called every time Lua calls a function;r': the hook is called every time Lua returns from a function;l': the hook is called every time Lua enters a new line of code.
Moreover,
with a count different from zero,
the hook is called also after every count instructions.
When called without arguments,
debug.sethook turns off the hook.
-When the hook is called, its first argument is a string
+When the hook is called, its first parameter is a string
describing the event that has triggered its call:
-"call" (or "tail call"),
-"return",
+"call", "tail call", "return",
"line", and "count".
For line events,
the hook also gets the new line number as its second parameter.
Inside a hook,
you can call getinfo with level 2 to get more information about
-the running function
-(level 0 is the getinfo function,
-and level 1 is the hook function).
+the running function.
+(Level 0 is the getinfo function,
+and level 1 is the hook function.)
debug.setlocal ([thread,] level, local, value)
This function assigns the value value to the local variable
with index local of the function at level level of the stack.
-The function returns nil if there is no local
+The function returns fail if there is no local
variable with the given index,
and raises an error when called with a level out of range.
(You can call getinfo to check whether the level is valid.)
Otherwise, it returns the name of the local variable.
See debug.getlocal for more information about
variable indices and names.
debug.setmetatable (value, table)
Sets the metatable for the given value to the given table
(which can be nil).
Returns value.
debug.setupvalue (f, up, value)
This function assigns the value value to the upvalue
with index up of the function f.
-The function returns nil if there is no upvalue
+The function returns fail if there is no upvalue
with the given index.
Otherwise, it returns the name of the upvalue.
+
+See debug.getupvalue for more information about upvalues.
+
+
-
debug.setuservalue (udata, value)debug.setuservalue (udata, value, n)
Sets the given value as
-the Lua value associated to the given udata.
+the n-th user value associated to the given udata.
udata must be a full userdata.
-Returns udata.
+Returns udata,
+or fail if the userdata does not have that value.
debug.traceback ([thread,] [message [, level]])
If message is present but is neither a string nor nil,
this function returns message without further processing.
Otherwise,
it returns a string with a traceback of the call stack.
The optional message string is appended
at the beginning of the traceback.
An optional level number tells at which level
to start the traceback
(default is 1, the function calling traceback).
debug.upvalueid (f, n)
Returns a unique identifier (as a light userdata)
for the upvalue numbered n
from the given function.
These unique identifiers allow a program to check whether different closures share upvalues. Lua closures that share an upvalue (that is, that access a same external local variable) will return identical ids for those upvalue indices.
debug.upvaluejoin (f1, n1, f2, n2)
Make the n1-th upvalue of the Lua closure f1
refer to the n2-th upvalue of the Lua closure f2.
Although Lua has been designed as an extension language,
to be embedded in a host C program,
it is also frequently used as a standalone language.
An interpreter for Lua as a standalone language,
called simply lua,
is provided with the standard distribution.
The standalone interpreter includes
-all standard libraries, including the debug library.
+all standard libraries.
Its usage is:
lua [options] [script [args]]
The options are:
-e stat: executes string stat;-l mod: "requires" mod and assigns the
- result to global @mod;-i: enters interactive mode after running script;-v: prints version information;-E: ignores environment variables;--: stops handling options;-: executes stdin as a file and stops handling options.-e stat: execute string stat;-i: enter interactive mode after running script;-l mod: "require" mod and assign the
+ result to global mod;-v: print version information;-E: ignore environment variables;-W: turn warnings on;--: stop handling options;-: execute stdin as a file and stop handling options.
After handling its options, lua runs the given script.
When called without arguments,
lua behaves as lua -v -i
when the standard input (stdin) is a terminal,
and as lua - otherwise.
-When called without option -E,
-the interpreter checks for an environment variable LUA_INIT_5_3
+When called without the option -E,
+the interpreter checks for an environment variable LUA_INIT_5_4
(or LUA_INIT if the versioned name is not defined)
before running any argument.
If the variable content has the format @filename,
then lua executes the file.
Otherwise, lua executes the string itself.
-When called with option -E,
-besides ignoring LUA_INIT,
-Lua also ignores
-the values of LUA_PATH and LUA_CPATH,
-setting the values of
-package.path and package.cpath
-with the default paths defined in luaconf.h.
+When called with the option -E,
+Lua does not consult any environment variables.
+In particular,
+the values of package.path and package.cpath
+are set with the default paths defined in luaconf.h.
-All options are handled in order, except -i and -E.
+The options -e, -l, and -W are handled in
+the order they appear.
For instance, an invocation like
- $ lua -e'a=1' -e 'print(a)' script.lua + $ lua -e 'a=1' -llib1 script.lua
-will first set a to 1, then print the value of a,
+will first set a to 1, then require the library lib1,
and finally run the file script.lua with no arguments.
(Here $ is the shell prompt. Your prompt may be different.)
Before running any code,
lua collects all command-line arguments
in a global table called arg.
The script name goes to index 0,
the first argument after the script name goes to index 1,
and so on.
Any arguments before the script name
(that is, the interpreter name plus its options)
go to negative indices.
For instance, in the call
$ lua -la b.lua t1 t2
the table is like this:
arg = { [-2] = "lua", [-1] = "-la",
[0] = "b.lua",
[1] = "t1", [2] = "t2" }
If there is no script in the call, the interpreter name goes to index 0, followed by the other arguments. For instance, the call
$ lua -e "print(arg[1])"
will print "-e".
If there is a script,
the script is called with arguments
arg[1], ···, arg[#arg].
-(Like all chunks in Lua,
-the script is compiled as a vararg function.)
+Like all chunks in Lua,
+the script is compiled as a vararg function.
In interactive mode, Lua repeatedly prompts and waits for a line. After reading a line, Lua first try to interpret the line as an expression. If it succeeds, it prints its value. Otherwise, it interprets the line as a statement. If you write an incomplete statement, the interpreter waits for its completion by issuing a different prompt.
If the global variable _PROMPT contains a string,
then its value is used as the prompt.
Similarly, if the global variable _PROMPT2 contains a string,
its value is used as the secondary prompt
(issued during incomplete statements).
In case of unprotected errors in the script,
the interpreter reports the error to the standard error stream.
If the error object is not a string but
has a metamethod __tostring,
the interpreter calls this metamethod to produce the final message.
Otherwise, the interpreter converts the error object to a string
and adds a stack traceback to it.
+When warnings are on,
+they are simply printed in the standard error output.
When finishing normally,
the interpreter closes its main Lua state
(see lua_close).
The script can avoid this step by
calling os.exit to terminate.
To allow the use of Lua as a
script interpreter in Unix systems,
-the standalone interpreter skips
-the first line of a chunk if it starts with #.
+Lua skips the first line of a file chunk if it starts with #.
Therefore, Lua scripts can be made into executable programs
by using chmod +x and the #! form,
as in
#!/usr/local/bin/lua
-(Of course,
+Of course,
the location of the Lua interpreter may be different in your machine.
If lua is in your PATH,
then
#!/usr/bin/env lua
-is a more portable solution.) +is a more portable solution.
Here we list the incompatibilities that you may find when moving a program -from Lua 5.2 to Lua 5.3. +from Lua 5.3 to Lua 5.4. + + +
You can avoid some incompatibilities by compiling Lua with
appropriate options (see file luaconf.h).
However,
all these compatibility options will be removed in the future.
+More often than not,
+compatibility issues arise when these compatibility options
+are removed.
+So, whenever you have the chance,
+you should try to test your code with a version of Lua compiled
+with all compatibility options turned off.
+That will ease transitions to newer versions of Lua.
Lua versions can always change the C API in ways that do not imply source-code changes in a program, such as the numeric values for constants or the implementation of functions as macros. Therefore, -you should not assume that binaries are compatible between +you should never assume that binaries are compatible between different Lua versions. Always recompile clients of the Lua API when using a new version.
Similarly, Lua versions can always change the internal representation of precompiled chunks; precompiled chunks are not compatible between different Lua versions.
The standard paths in the official distribution may change between versions. -
-You can fix these differences by forcing a number to be a float
-(in Lua 5.2 all numbers were float),
-in particular writing constants with an ending .0
-or using x = x + 0.0 to convert a variable.
-(This recommendation is only for a quick fix
-for an occasional incompatibility;
-it is not a general guideline for good programming.
-For good programming,
-use floats where you need floats
-and integers where you need integers.)
+The coercion of strings to numbers in
+arithmetic and bitwise operations
+has been removed from the core language.
+The string library does a similar job
+for arithmetic (but not for bitwise) operations
+using the string metamethods.
+However, unlike in previous versions,
+the new implementation preserves the implicit type of the numeral
+in the string.
+For instance, the result of "1" + "2" now is an integer,
+not a float.
+
.0 suffix
-to the result if it looks like an integer.
-(For instance, the float 2.0 will be printed as 2.0,
-not as 2.)
-You should always use an explicit format
-when you need a specific format for numbers.
+The use of the __lt metamethod to emulate __le
+has been removed.
+When needed, this metamethod must be explicitly defined.
+-(Formally this is not an incompatibility, -because Lua does not specify how numbers are formatted as strings, -but some programs assumed a specific format.) +
__gc metamethods that are not functions.
+Any value will be called, if present.
+(Non-callable values will generate a warning,
+like any other error when calling a finalizer.)
bit32 library has been deprecated.
-It is easy to require a compatible external library or,
-better yet, to replace its functions with appropriate bitwise operations.
-(Keep in mind that bit32 operates on 32-bit integers,
-while the bitwise operators in Lua 5.3 operate on Lua integers,
-which by default have 64 bits.)
-print does not call tostring
+to format its arguments;
+instead, it has this functionality hardwired.
+You should use __tostring to modify how values are printed.
ipairs iterator now respects metamethods and
-its __ipairs metamethod has been deprecated.
+The pseudo-random number generator used by the function math.random
+now starts with a somewhat random seed.
+Moreover, it uses a different algorithm.
io.read do not have a starting '*' anymore.
-For compatibility, Lua will continue to accept (and ignore) this character.
+By default, the decoding functions in the utf8 library
+do not accept surrogates as valid code points.
+An extra parameter in these functions makes them more permissive.
atan2, cosh, sinh, tanh, pow,
-frexp, and ldexp.
-You can replace math.pow(x,y) with x^y;
-you can replace math.atan2 with math.atan,
-which now accepts one or two arguments;
-you can replace math.ldexp(x,exp) with x * 2.0^exp.
-For the other operations,
-you can either use an external library or
-implement them in Lua.
+The options "setpause" and "setstepmul"
+of the function collectgarbage are deprecated.
+You should use the new option "incremental" to set them.
require
-changed the way it handles versioned names.
-Now, the version should come after the module name
-(as is usual in most other tools).
-For compatibility, that searcher still tries the old format
-if it cannot find an open function according to the new style.
-(Lua 5.2 already worked that way,
-but it did not document the change.)
-collectgarbage("count") now returns only one result.
-(You can compute that second result from the fractional part
-of the first result.)
+The function io.lines now returns four values,
+instead of just one.
+That can be a problem when it is used as the sole
+argument to another function that has optional parameters,
+such as in load(io.lines(filename, "L")).
+To fix that issue,
+you can wrap the call into parentheses,
+to adjust its number of results to one.
lua_getctx,
-so lua_getctx has been removed.
-Adapt your code accordingly.
+Full userdata now has an arbitrary number of associated user values.
+Therefore, the functions lua_newuserdata,
+lua_setuservalue, and lua_getuservalue were
+replaced by lua_newuserdatauv,
+lua_setiuservalue, and lua_getiuservalue,
+which have an extra argument.
+
+
++For compatibility, the old names still work as macros assuming +one single user value. +Note, however, that userdata with zero user values +are more efficient memory-wise. +
lua_resume has an extra parameter.
+This out parameter returns the number of values on
+the top of the stack that were yielded or returned by the coroutine.
+(In previous versions,
+those values were the entire stack.)
lua_dump has an extra parameter, strip.
-Use 0 as the value of this parameter to get the old behavior.
+The function lua_version returns the version number,
+instead of an address of the version number.
+The Lua core should work correctly with libraries using their
+own static copies of the same core,
+so there is no need to check whether they are using the same
+address space.
lua_pushunsigned, lua_tounsigned, lua_tounsignedx,
-luaL_checkunsigned, luaL_optunsigned)
-were deprecated.
-Use their signed equivalents with a type cast.
+The constant LUA_ERRGCMM was removed.
+Errors in finalizers are never propagated;
+instead, they generate a warning.
luaL_checkint, luaL_optint, luaL_checklong, luaL_optlong)
-were deprecated.
-Use their equivalent over lua_Integer with a type cast
-(or, when possible, use lua_Integer in your code).
+The options LUA_GCSETPAUSE and LUA_GCSETSTEPMUL
+of the function lua_gc are deprecated.
+You should use the new option LUA_GCINC to set them.
Here is the complete syntax of Lua in extended BNF. As usual in extended BNF, {A} means 0 or more As, and [A] means an optional A. (For operator precedences, see §3.4.8; for a description of the terminals Name, Numeral, and LiteralString, see §3.1.)
chunk ::= block
block ::= {stat} [retstat]
stat ::= ‘;’ |
varlist ‘=’ explist |
functioncall |
label |
break |
goto Name |
do block end |
while exp do block end |
repeat block until exp |
if exp then block {elseif exp then block} [else block] end |
for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end |
for namelist in explist do block end |
function funcname funcbody |
local function Name funcbody |
- local namelist [‘=’ explist]
+ local attnamelist [‘=’ explist]
+
+ attnamelist ::= Name attrib {‘,’ Name attrib}
+
+ attrib ::= [‘<’ Name ‘>’]
retstat ::= return [explist] [‘;’]
label ::= ‘::’ Name ‘::’
funcname ::= Name {‘.’ Name} [‘:’ Name]
varlist ::= var {‘,’ var}
var ::= Name | prefixexp ‘[’ exp ‘]’ | prefixexp ‘.’ Name
namelist ::= Name {‘,’ Name}
explist ::= exp {‘,’ exp}
exp ::= nil | false | true | Numeral | LiteralString | ‘...’ | functiondef |
prefixexp | tableconstructor | exp binop exp | unop exp
prefixexp ::= var | functioncall | ‘(’ exp ‘)’
functioncall ::= prefixexp args | prefixexp ‘:’ Name args
args ::= ‘(’ [explist] ‘)’ | tableconstructor | LiteralString
functiondef ::= function funcbody
funcbody ::= ‘(’ [parlist] ‘)’ block end
parlist ::= namelist [‘,’ ‘...’] | ‘...’
tableconstructor ::= ‘{’ [fieldlist] ‘}’
fieldlist ::= field {fieldsep field} [fieldsep]
field ::= ‘[’ exp ‘]’ ‘=’ exp | Name ‘=’ exp | exp
fieldsep ::= ‘,’ | ‘;’
binop ::= ‘+’ | ‘-’ | ‘*’ | ‘/’ | ‘//’ | ‘^’ | ‘%’ |
‘&’ | ‘~’ | ‘|’ | ‘>>’ | ‘<<’ | ‘..’ |
‘<’ | ‘<=’ | ‘>’ | ‘>=’ | ‘==’ | ‘~=’ |
and | or
unop ::= ‘-’ | not | ‘#’ | ‘~’
-
diff --git a/doc/readme.html b/doc/readme.html index 50716f42d0cf..e20a9bda138a 100644 --- a/doc/readme.html +++ b/doc/readme.html @@ -1,365 +1,340 @@ -
-Welcome to Lua 5.3
+Welcome to Lua 5.4
-Lua is a powerful, fast, lightweight, embeddable scripting language +Lua is a powerful, efficient, lightweight, embeddable scripting language developed by a team at PUC-Rio, the Pontifical Catholic University of Rio de Janeiro in Brazil. Lua is free software -used in many products and projects around the world. +used in +many products and projects +around the world.
Lua's official web site provides complete information about Lua, including an executive summary and updated documentation, especially the -reference manual, +reference manual, which may differ slightly from the local copy distributed in this package.
Lua is distributed in source form. You need to build it before using it. Building Lua should be straightforward because Lua is implemented in pure ANSI C and compiles unmodified in all known platforms that have an ANSI C compiler. Lua also compiles unmodified as C++. -The instructions given below for building Lua are for Unix-like platforms. +The instructions given below for building Lua are for Unix-like platforms, +such as Linux and Mac OS X. See also instructions for other systems and customization options.
If you don't have the time or the inclination to compile Lua yourself, get a binary from LuaBinaries. Try also LuaDist, a multi-platform distribution of Lua that includes batteries.
-In most Unix-like platforms, simply do "make" with a suitable target. +In most common Unix-like platforms, simply do "make". Here are the details.
+
- aix bsd c89 freebsd generic linux macosx mingw posix solaris + guess aix bsd c89 freebsd generic linux linux-readline macosx mingw posix solaris
If your platform is listed, just do "make xxx", where xxx is your platform name.
If your platform is not listed, try the closest one or posix, generic, c89, in this order.
-If you're running Linux and get compilation errors, +If you're running Linux, try "make linux-readline" to build the interactive Lua interpreter with handy line-editing and history capabilities. +If you get compilation errors, make sure you have installed the readline development package (which is probably named libreadline-dev or readline-devel). If you get link errors after that, -then try "make linux MYLIBS=-ltermcap". +then try "make linux-readline MYLIBS=-ltermcap".
Once you have built Lua, you may want to install it in an official place in your system. In this case, do "make install". The official place and the way to install files are defined in the Makefile. You'll - probably need the right permissions to install files. + probably need the right permissions to install files, and so may need to do "sudo make install".
- To build and install Lua in one step, do "make xxx install", + To build and install Lua in one step, do "make all install", + or "make xxx install", where xxx is your platform name.
- To install Lua locally, do "make local". + To install Lua locally after building it, do "make local". This will create a directory install with subdirectories bin, include, lib, man, share, and install Lua as listed below. To install Lua locally, but in some other directory, do "make install INSTALL_TOP=xxx", where xxx is your chosen directory. The installation starts in the src and doc directories, so take care if INSTALL_TOP is not an absolute path.
These are the only directories you need for development. If you only want to run Lua programs, you only need the files in bin and man. The files in include and lib are needed for embedding Lua in C or C++ programs.
Three kinds of things can be customized by editing a file:
You don't actually need to edit the Makefiles because you may set the relevant variables in the command line when invoking make. Nevertheless, it's probably best to edit and save the Makefiles to record the changes you've made.
On the other hand, if you need to customize some Lua features, you'll need to edit src/luaconf.h before building and installing Lua. The edited file will be the one installed, and it will be used by any Lua clients that you build, to ensure consistency. Further customization is available to experts by editing the Lua sources.
If you're not using the usual Unix tools, then the instructions for building Lua depend on the compiler you use. You'll need to create projects (or whatever your compiler uses) for building the library, the interpreter, and the compiler, as follows:
- To use Lua as a library in your own programs you'll need to know how to + To use Lua as a library in your own programs, you'll need to know how to create and use libraries with your compiler. Moreover, to dynamically load - C libraries for Lua you'll need to know how to create dynamic libraries + C libraries for Lua, you'll need to know how to create dynamic libraries and you'll need to make sure that the Lua API functions are accessible to those dynamic libraries — but don't link the Lua library into each dynamic library. For Unix, we recommend that the Lua library be linked statically into the host program and its symbols exported for dynamic linking; src/Makefile does this for the Lua interpreter. For Windows, we recommend that the Lua library be a DLL. In all cases, the compiler luac should be linked statically.
As mentioned above, you may edit src/luaconf.h to customize some features before building Lua. -
-Here are the main changes introduced in Lua 5.3. +Here are the main changes introduced in Lua 5.4. The reference manual lists the incompatibilities that had to be introduced.
ipairs and the table library respect metamethods
-string.dump
-table.move
-string.pack
-string.unpack
-string.packsize
-lua_gettable and similar functions return type of resulted value
-lua_dump
-lua_geti
-lua_seti
-lua_isyieldable
-lua_numbertointeger
-lua_rotate
-lua_stringtonumber
-arg table available to all code
+
![[osi certified]](osi-certified-72x60.png)
Lua is free software distributed under the terms of the
MIT license
reproduced below;
it may be used for any purpose, including commercial purposes,
at absolutely no cost without having to ask us.
The only requirement is that if you do use Lua,
then you should give us credit by including the appropriate copyright notice somewhere in your product or its documentation.
For details, see
this.
Copyright © 1994–2020 Lua.org, PUC-Rio.Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/src/Makefile b/src/Makefile index a13afb996273..a99735a44145 100644 --- a/src/Makefile +++ b/src/Makefile @@ -1,197 +1,220 @@ # Makefile for building Lua # See ../doc/readme.html for installation and customization instructions. # == CHANGE THE SETTINGS BELOW TO SUIT YOUR ENVIRONMENT ======================= # Your platform. See PLATS for possible values. -PLAT= none +PLAT= guess CC= gcc -std=gnu99 -CFLAGS= -O2 -Wall -Wextra -DLUA_COMPAT_5_2 $(SYSCFLAGS) $(MYCFLAGS) +CFLAGS= -O2 -Wall -Wextra -DLUA_COMPAT_5_3 $(SYSCFLAGS) $(MYCFLAGS) LDFLAGS= $(SYSLDFLAGS) $(MYLDFLAGS) LIBS= -lm $(SYSLIBS) $(MYLIBS) AR= ar rcu RANLIB= ranlib RM= rm -f +UNAME= uname SYSCFLAGS= SYSLDFLAGS= SYSLIBS= MYCFLAGS= MYLDFLAGS= MYLIBS= MYOBJS= +# Special flags for compiler modules; -Os reduces code size. +CMCFLAGS= + # == END OF USER SETTINGS -- NO NEED TO CHANGE ANYTHING BELOW THIS LINE ======= -PLATS= aix bsd c89 freebsd generic linux macosx mingw posix solaris +PLATS= guess aix bsd c89 freebsd generic linux linux-readline macosx mingw posix solaris LUA_A= liblua.a -CORE_O= lapi.o lcode.o lctype.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o \ - lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o \ - ltm.o lundump.o lvm.o lzio.o -LIB_O= lauxlib.o lbaselib.o lbitlib.o lcorolib.o ldblib.o liolib.o \ - lmathlib.o loslib.o lstrlib.o ltablib.o lutf8lib.o loadlib.o linit.o +CORE_O= lapi.o lcode.o lctype.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o ltm.o lundump.o lvm.o lzio.o +LIB_O= lauxlib.o lbaselib.o lcorolib.o ldblib.o liolib.o lmathlib.o loadlib.o loslib.o lstrlib.o ltablib.o lutf8lib.o linit.o BASE_O= $(CORE_O) $(LIB_O) $(MYOBJS) LUA_T= lua LUA_O= lua.o LUAC_T= luac LUAC_O= luac.o ALL_O= $(BASE_O) $(LUA_O) $(LUAC_O) ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T) ALL_A= $(LUA_A) # Targets start here. default: $(PLAT) all: $(ALL_T) o: $(ALL_O) a: $(ALL_A) $(LUA_A): $(BASE_O) $(AR) $@ $(BASE_O) $(RANLIB) $@ $(LUA_T): $(LUA_O) $(LUA_A) $(CC) -o $@ $(LDFLAGS) $(LUA_O) $(LUA_A) $(LIBS) $(LUAC_T): $(LUAC_O) $(LUA_A) $(CC) -o $@ $(LDFLAGS) $(LUAC_O) $(LUA_A) $(LIBS) +test: + ./lua -v + clean: $(RM) $(ALL_T) $(ALL_O) depend: @$(CC) $(CFLAGS) -MM l*.c echo: @echo "PLAT= $(PLAT)" @echo "CC= $(CC)" @echo "CFLAGS= $(CFLAGS)" @echo "LDFLAGS= $(SYSLDFLAGS)" @echo "LIBS= $(LIBS)" @echo "AR= $(AR)" @echo "RANLIB= $(RANLIB)" @echo "RM= $(RM)" + @echo "UNAME= $(UNAME)" -# Convenience targets for popular platforms +# Convenience targets for popular platforms. ALL= all -none: - @echo "Please do 'make PLATFORM' where PLATFORM is one of these:" +help: + @echo "Do 'make PLATFORM' where PLATFORM is one of these:" @echo " $(PLATS)" + @echo "See doc/readme.html for complete instructions." + +guess: + @echo Guessing `$(UNAME)` + @$(MAKE) `$(UNAME)` -aix: +AIX aix: $(MAKE) $(ALL) CC="xlc" CFLAGS="-O2 -DLUA_USE_POSIX -DLUA_USE_DLOPEN" SYSLIBS="-ldl" SYSLDFLAGS="-brtl -bexpall" bsd: $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN" SYSLIBS="-Wl,-E" c89: $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_C89" CC="gcc -std=c89" @echo '' @echo '*** C89 does not guarantee 64-bit integers for Lua.' @echo '' - -freebsd: - $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX -I/usr/include/edit" SYSLIBS="-Wl,-E -ledit" CC="cc" +FreeBSD NetBSD OpenBSD freebsd: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX -DLUA_USE_READLINE -I/usr/include/edit" SYSLIBS="-Wl,-E -ledit" CC="cc" generic: $(ALL) -linux: - $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX" SYSLIBS="-Wl,-E -ldl -lreadline" +Linux linux: linux-noreadline + +linux-noreadline: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX" SYSLIBS="-Wl,-E -ldl" -macosx: - $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_MACOSX" SYSLIBS="-lreadline" +linux-readline: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_LINUX -DLUA_USE_READLINE" SYSLIBS="-Wl,-E -ldl -lreadline" + +Darwin macos macosx: + $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_MACOSX -DLUA_USE_READLINE" SYSLIBS="-lreadline" mingw: - $(MAKE) "LUA_A=lua53.dll" "LUA_T=lua.exe" \ + $(MAKE) "LUA_A=lua54.dll" "LUA_T=lua.exe" \ "AR=$(CC) -shared -o" "RANLIB=strip --strip-unneeded" \ "SYSCFLAGS=-DLUA_BUILD_AS_DLL" "SYSLIBS=" "SYSLDFLAGS=-s" lua.exe $(MAKE) "LUAC_T=luac.exe" luac.exe posix: $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX" -solaris: +SunOS solaris: $(MAKE) $(ALL) SYSCFLAGS="-DLUA_USE_POSIX -DLUA_USE_DLOPEN -D_REENTRANT" SYSLIBS="-ldl" -# list targets that do not create files (but not all makes understand .PHONY) -.PHONY: all $(PLATS) default o a clean depend echo none +# Targets that do not create files (not all makes understand .PHONY). +.PHONY: all $(PLATS) help test clean default o a depend echo + +# Compiler modules may use special flags. +llex.o: + $(CC) $(CFLAGS) $(CMCFLAGS) -c llex.c + +lparser.o: + $(CC) $(CFLAGS) $(CMCFLAGS) -c lparser.c + +lcode.o: + $(CC) $(CFLAGS) $(CMCFLAGS) -c lcode.c # DO NOT DELETE lapi.o: lapi.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h lstring.h \ ltable.h lundump.h lvm.h lauxlib.o: lauxlib.c lprefix.h lua.h luaconf.h lauxlib.h lbaselib.o: lbaselib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h -lbitlib.o: lbitlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lcode.o: lcode.c lprefix.h lua.h luaconf.h lcode.h llex.h lobject.h \ llimits.h lzio.h lmem.h lopcodes.h lparser.h ldebug.h lstate.h ltm.h \ ldo.h lgc.h lstring.h ltable.h lvm.h lcorolib.o: lcorolib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lctype.o: lctype.c lprefix.h lctype.h lua.h luaconf.h llimits.h ldblib.o: ldblib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h ldebug.o: ldebug.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ lobject.h ltm.h lzio.h lmem.h lcode.h llex.h lopcodes.h lparser.h \ ldebug.h ldo.h lfunc.h lstring.h lgc.h ltable.h lvm.h ldo.o: ldo.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h lopcodes.h \ lparser.h lstring.h ltable.h lundump.h lvm.h ldump.o: ldump.c lprefix.h lua.h luaconf.h lobject.h llimits.h lstate.h \ ltm.h lzio.h lmem.h lundump.h -lfunc.o: lfunc.c lprefix.h lua.h luaconf.h lfunc.h lobject.h llimits.h \ - lgc.h lstate.h ltm.h lzio.h lmem.h +lfunc.o: lfunc.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ + llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lgc.h lgc.o: lgc.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lgc.h lstring.h ltable.h linit.o: linit.c lprefix.h lua.h luaconf.h lualib.h lauxlib.h liolib.o: liolib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h llex.o: llex.c lprefix.h lua.h luaconf.h lctype.h llimits.h ldebug.h \ lstate.h lobject.h ltm.h lzio.h lmem.h ldo.h lgc.h llex.h lparser.h \ lstring.h ltable.h lmathlib.o: lmathlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lmem.o: lmem.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ llimits.h ltm.h lzio.h lmem.h ldo.h lgc.h loadlib.o: loadlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lobject.o: lobject.c lprefix.h lua.h luaconf.h lctype.h llimits.h \ ldebug.h lstate.h lobject.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h \ lvm.h lopcodes.o: lopcodes.c lprefix.h lopcodes.h llimits.h lua.h luaconf.h loslib.o: loslib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lparser.o: lparser.c lprefix.h lua.h luaconf.h lcode.h llex.h lobject.h \ llimits.h lzio.h lmem.h lopcodes.h lparser.h ldebug.h lstate.h ltm.h \ ldo.h lfunc.h lstring.h lgc.h ltable.h lstate.o: lstate.c lprefix.h lua.h luaconf.h lapi.h llimits.h lstate.h \ lobject.h ltm.h lzio.h lmem.h ldebug.h ldo.h lfunc.h lgc.h llex.h \ lstring.h ltable.h lstring.o: lstring.c lprefix.h lua.h luaconf.h ldebug.h lstate.h \ lobject.h llimits.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h lstrlib.o: lstrlib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h ltable.o: ltable.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ llimits.h ltm.h lzio.h lmem.h ldo.h lgc.h lstring.h ltable.h lvm.h ltablib.o: ltablib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h ltm.o: ltm.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ - llimits.h ltm.h lzio.h lmem.h ldo.h lstring.h lgc.h ltable.h lvm.h + llimits.h ltm.h lzio.h lmem.h ldo.h lgc.h lstring.h ltable.h lvm.h lua.o: lua.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h -luac.o: luac.c lprefix.h lua.h luaconf.h lauxlib.h lobject.h llimits.h \ - lstate.h ltm.h lzio.h lmem.h lundump.h ldebug.h lopcodes.h +luac.o: luac.c lprefix.h lua.h luaconf.h lauxlib.h ldebug.h lstate.h \ + lobject.h llimits.h ltm.h lzio.h lmem.h lopcodes.h lopnames.h lundump.h lundump.o: lundump.c lprefix.h lua.h luaconf.h ldebug.h lstate.h \ lobject.h llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lstring.h lgc.h \ lundump.h lutf8lib.o: lutf8lib.c lprefix.h lua.h luaconf.h lauxlib.h lualib.h lvm.o: lvm.c lprefix.h lua.h luaconf.h ldebug.h lstate.h lobject.h \ llimits.h ltm.h lzio.h lmem.h ldo.h lfunc.h lgc.h lopcodes.h lstring.h \ - ltable.h lvm.h + ltable.h lvm.h ljumptab.h lzio.o: lzio.c lprefix.h lua.h luaconf.h llimits.h lmem.h lstate.h \ lobject.h ltm.h lzio.h # (end of Makefile) diff --git a/src/lapi.c b/src/lapi.c index 711895b395b6..c824da27cbc4 100644 --- a/src/lapi.c +++ b/src/lapi.c @@ -1,1299 +1,1431 @@ /* -** $Id: lapi.c,v 2.259.1.2 2017/12/06 18:35:12 roberto Exp $ +** $Id: lapi.c $ ** Lua API ** See Copyright Notice in lua.h */ #define lapi_c #define LUA_CORE #include "lprefix.h" +#include
u.key_tt)
+#define keyval(node) ((node)->u.key_val)
+
+#define keyisnil(node) (keytt(node) == LUA_TNIL)
+#define keyisinteger(node) (keytt(node) == LUA_VNUMINT)
+#define keyival(node) (keyval(node).i)
+#define keyisshrstr(node) (keytt(node) == ctb(LUA_VSHRSTR))
+#define keystrval(node) (gco2ts(keyval(node).gc))
+
+#define setnilkey(node) (keytt(node) = LUA_TNIL)
+
+#define keyiscollectable(n) (keytt(n) & BIT_ISCOLLECTABLE)
+
+#define gckey(n) (keyval(n).gc)
+#define gckeyN(n) (keyiscollectable(n) ? gckey(n) : NULL)
+
/*
-** 'module' operation for hashing (size is always a power of 2)
+** Dead keys in tables have the tag DEADKEY but keep their original
+** gcvalue. This distinguishes them from regular keys but allows them to
+** be found when searched in a special way. ('next' needs that to find
+** keys removed from a table during a traversal.)
*/
-#define lmod(s,size) \
- (check_exp((size&(size-1))==0, (cast(int, (s) & ((size)-1)))))
+#define setdeadkey(node) (keytt(node) = LUA_TDEADKEY)
+#define keyisdead(node) (keytt(node) == LUA_TDEADKEY)
+/* }================================================================== */
-#define twoto(x) (1<<(x))
-#define sizenode(t) (twoto((t)->lsizenode))
/*
-** (address of) a fixed nil value
+** 'module' operation for hashing (size is always a power of 2)
*/
-#define luaO_nilobject (&luaO_nilobject_)
+#define lmod(s,size) \
+ (check_exp((size&(size-1))==0, (cast_int((s) & ((size)-1)))))
+
+#define twoto(x) (1<<(x))
+#define sizenode(t) (twoto((t)->lsizenode))
-LUAI_DDEC const TValue luaO_nilobject_;
/* size of buffer for 'luaO_utf8esc' function */
#define UTF8BUFFSZ 8
-LUAI_FUNC int luaO_int2fb (unsigned int x);
-LUAI_FUNC int luaO_fb2int (int x);
LUAI_FUNC int luaO_utf8esc (char *buff, unsigned long x);
LUAI_FUNC int luaO_ceillog2 (unsigned int x);
+LUAI_FUNC int luaO_rawarith (lua_State *L, int op, const TValue *p1,
+ const TValue *p2, TValue *res);
LUAI_FUNC void luaO_arith (lua_State *L, int op, const TValue *p1,
- const TValue *p2, TValue *res);
+ const TValue *p2, StkId res);
LUAI_FUNC size_t luaO_str2num (const char *s, TValue *o);
LUAI_FUNC int luaO_hexavalue (int c);
-LUAI_FUNC void luaO_tostring (lua_State *L, StkId obj);
+LUAI_FUNC void luaO_tostring (lua_State *L, TValue *obj);
LUAI_FUNC const char *luaO_pushvfstring (lua_State *L, const char *fmt,
va_list argp);
LUAI_FUNC const char *luaO_pushfstring (lua_State *L, const char *fmt, ...);
-LUAI_FUNC void luaO_chunkid (char *out, const char *source, size_t len);
+LUAI_FUNC void luaO_chunkid (char *out, const char *source, size_t srclen);
#endif
diff --git a/src/lopcodes.c b/src/lopcodes.c
index 5ca3eb261a48..c67aa227c587 100644
--- a/src/lopcodes.c
+++ b/src/lopcodes.c
@@ -1,124 +1,104 @@
/*
-** $Id: lopcodes.c,v 1.55.1.1 2017/04/19 17:20:42 roberto Exp $
+** $Id: lopcodes.c $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
#define lopcodes_c
#define LUA_CORE
#include "lprefix.h"
-#include