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contrib/libcxxabi/src/include/refstring.h
- This file was added.
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//===------------------------ __refstring ---------------------------------===// | |||||
// | |||||
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||||
// See https://llvm.org/LICENSE.txt for license information. | |||||
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||||
// | |||||
//===----------------------------------------------------------------------===// | |||||
// FIXME: This file is copied from libcxx/src/include/refstring.h. Instead of | |||||
// duplicating the file in libc++abi we should require that the libc++ sources | |||||
// are available when building libc++abi. | |||||
#ifndef _LIBCPPABI_REFSTRING_H | |||||
#define _LIBCPPABI_REFSTRING_H | |||||
#include <__config> | |||||
#include <stdexcept> | |||||
#include <cstddef> | |||||
#include <cstring> | |||||
#ifdef __APPLE__ | |||||
#include <dlfcn.h> | |||||
#include <mach-o/dyld.h> | |||||
#endif | |||||
#include "atomic_support.h" | |||||
_LIBCPP_BEGIN_NAMESPACE_STD | |||||
namespace __refstring_imp { namespace { | |||||
typedef int count_t; | |||||
struct _Rep_base { | |||||
std::size_t len; | |||||
std::size_t cap; | |||||
count_t count; | |||||
}; | |||||
inline _Rep_base* rep_from_data(const char *data_) noexcept { | |||||
char *data = const_cast<char *>(data_); | |||||
return reinterpret_cast<_Rep_base *>(data - sizeof(_Rep_base)); | |||||
} | |||||
inline char * data_from_rep(_Rep_base *rep) noexcept { | |||||
char *data = reinterpret_cast<char *>(rep); | |||||
return data + sizeof(*rep); | |||||
} | |||||
#if defined(__APPLE__) | |||||
inline | |||||
const char* compute_gcc_empty_string_storage() _NOEXCEPT | |||||
{ | |||||
void* handle = dlopen("/usr/lib/libstdc++.6.dylib", RTLD_NOLOAD); | |||||
if (handle == nullptr) | |||||
return nullptr; | |||||
void* sym = dlsym(handle, "_ZNSs4_Rep20_S_empty_rep_storageE"); | |||||
if (sym == nullptr) | |||||
return nullptr; | |||||
return data_from_rep(reinterpret_cast<_Rep_base *>(sym)); | |||||
} | |||||
inline | |||||
const char* | |||||
get_gcc_empty_string_storage() _NOEXCEPT | |||||
{ | |||||
static const char* p = compute_gcc_empty_string_storage(); | |||||
return p; | |||||
} | |||||
#endif | |||||
}} // namespace __refstring_imp | |||||
using namespace __refstring_imp; | |||||
inline | |||||
__libcpp_refstring::__libcpp_refstring(const char* msg) { | |||||
std::size_t len = strlen(msg); | |||||
_Rep_base* rep = static_cast<_Rep_base *>(::operator new(sizeof(*rep) + len + 1)); | |||||
rep->len = len; | |||||
rep->cap = len; | |||||
rep->count = 0; | |||||
char *data = data_from_rep(rep); | |||||
std::memcpy(data, msg, len + 1); | |||||
__imp_ = data; | |||||
} | |||||
inline | |||||
__libcpp_refstring::__libcpp_refstring(const __libcpp_refstring &s) _NOEXCEPT | |||||
: __imp_(s.__imp_) | |||||
{ | |||||
if (__uses_refcount()) | |||||
__libcpp_atomic_add(&rep_from_data(__imp_)->count, 1); | |||||
} | |||||
inline | |||||
__libcpp_refstring& __libcpp_refstring::operator=(__libcpp_refstring const& s) _NOEXCEPT { | |||||
bool adjust_old_count = __uses_refcount(); | |||||
struct _Rep_base *old_rep = rep_from_data(__imp_); | |||||
__imp_ = s.__imp_; | |||||
if (__uses_refcount()) | |||||
__libcpp_atomic_add(&rep_from_data(__imp_)->count, 1); | |||||
if (adjust_old_count) | |||||
{ | |||||
if (__libcpp_atomic_add(&old_rep->count, count_t(-1)) < 0) | |||||
{ | |||||
::operator delete(old_rep); | |||||
} | |||||
} | |||||
return *this; | |||||
} | |||||
inline | |||||
__libcpp_refstring::~__libcpp_refstring() { | |||||
if (__uses_refcount()) { | |||||
_Rep_base* rep = rep_from_data(__imp_); | |||||
if (__libcpp_atomic_add(&rep->count, count_t(-1)) < 0) { | |||||
::operator delete(rep); | |||||
} | |||||
} | |||||
} | |||||
inline | |||||
bool __libcpp_refstring::__uses_refcount() const { | |||||
#ifdef __APPLE__ | |||||
return __imp_ != get_gcc_empty_string_storage(); | |||||
#else | |||||
return true; | |||||
#endif | |||||
} | |||||
_LIBCPP_END_NAMESPACE_STD | |||||
#endif //_LIBCPPABI_REFSTRING_H |