mirror of
https://github.com/jart/cosmopolitan.git
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159 lines
4.4 KiB
C++
159 lines
4.4 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___MUTEX_ONCE_FLAG_H
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#define _LIBCPP___MUTEX_ONCE_FLAG_H
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#include <__config>
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#include <__functional/invoke.h>
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#include <__memory/shared_ptr.h> // __libcpp_acquire_load
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#include <__tuple/tuple_indices.h>
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#include <__tuple/tuple_size.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#include <cstdint>
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#ifndef _LIBCPP_CXX03_LANG
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# include <tuple>
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#endif
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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struct _LIBCPP_TEMPLATE_VIS once_flag;
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Callable, class... _Args>
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_LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, _Callable&&, _Args&&...);
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#else // _LIBCPP_CXX03_LANG
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template <class _Callable>
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_LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, _Callable&);
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template <class _Callable>
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_LIBCPP_HIDE_FROM_ABI void call_once(once_flag&, const _Callable&);
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#endif // _LIBCPP_CXX03_LANG
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struct _LIBCPP_TEMPLATE_VIS once_flag {
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR once_flag() _NOEXCEPT : __state_(_Unset) {}
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once_flag(const once_flag&) = delete;
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once_flag& operator=(const once_flag&) = delete;
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#if defined(_LIBCPP_ABI_MICROSOFT)
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typedef uintptr_t _State_type;
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#else
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typedef unsigned long _State_type;
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#endif
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static const _State_type _Unset = 0;
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static const _State_type _Pending = 1;
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static const _State_type _Complete = ~_State_type(0);
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private:
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_State_type __state_;
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Callable, class... _Args>
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friend void call_once(once_flag&, _Callable&&, _Args&&...);
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#else // _LIBCPP_CXX03_LANG
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template <class _Callable>
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friend void call_once(once_flag&, _Callable&);
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template <class _Callable>
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friend void call_once(once_flag&, const _Callable&);
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#endif // _LIBCPP_CXX03_LANG
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};
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Fp>
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class __call_once_param {
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_Fp& __f_;
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public:
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_LIBCPP_HIDE_FROM_ABI explicit __call_once_param(_Fp& __f) : __f_(__f) {}
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_LIBCPP_HIDE_FROM_ABI void operator()() {
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typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 1>::type _Index;
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__execute(_Index());
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}
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private:
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template <size_t... _Indices>
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_LIBCPP_HIDE_FROM_ABI void __execute(__tuple_indices<_Indices...>) {
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std::__invoke(std::get<0>(std::move(__f_)), std::get<_Indices>(std::move(__f_))...);
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}
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};
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#else
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template <class _Fp>
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class __call_once_param {
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_Fp& __f_;
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public:
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_LIBCPP_HIDE_FROM_ABI explicit __call_once_param(_Fp& __f) : __f_(__f) {}
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_LIBCPP_HIDE_FROM_ABI void operator()() { __f_(); }
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};
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#endif
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template <class _Fp>
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void _LIBCPP_HIDE_FROM_ABI __call_once_proxy(void* __vp) {
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__call_once_param<_Fp>* __p = static_cast<__call_once_param<_Fp>*>(__vp);
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(*__p)();
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}
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_LIBCPP_EXPORTED_FROM_ABI void __call_once(volatile once_flag::_State_type&, void*, void (*)(void*));
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Callable, class... _Args>
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inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, _Callable&& __func, _Args&&... __args) {
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if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
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typedef tuple<_Callable&&, _Args&&...> _Gp;
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_Gp __f(std::forward<_Callable>(__func), std::forward<_Args>(__args)...);
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__call_once_param<_Gp> __p(__f);
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std::__call_once(__flag.__state_, &__p, &__call_once_proxy<_Gp>);
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}
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}
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#else // _LIBCPP_CXX03_LANG
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template <class _Callable>
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inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, _Callable& __func) {
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if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
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__call_once_param<_Callable> __p(__func);
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std::__call_once(__flag.__state_, &__p, &__call_once_proxy<_Callable>);
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}
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}
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template <class _Callable>
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inline _LIBCPP_HIDE_FROM_ABI void call_once(once_flag& __flag, const _Callable& __func) {
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if (__libcpp_acquire_load(&__flag.__state_) != once_flag::_Complete) {
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__call_once_param<const _Callable> __p(__func);
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std::__call_once(__flag.__state_, &__p, &__call_once_proxy<const _Callable>);
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}
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}
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#endif // _LIBCPP_CXX03_LANG
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___MUTEX_ONCE_FLAG_H
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