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53 lines
2 KiB
C++
53 lines
2 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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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___FUNCTIONAL_COMPOSE_H
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#define _LIBCPP___FUNCTIONAL_COMPOSE_H
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#include <__config>
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#include <__functional/invoke.h>
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#include <__functional/perfect_forward.h>
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#include <__type_traits/decay.h>
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#include <__utility/forward.h>
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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_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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struct __compose_op {
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template <class _Fn1, class _Fn2, class... _Args>
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_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn1&& __f1, _Fn2&& __f2, _Args&&... __args) const noexcept(noexcept(
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std::invoke(std::forward<_Fn1>(__f1), std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...))))
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-> decltype(std::invoke(std::forward<_Fn1>(__f1),
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std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...))) {
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return std::invoke(std::forward<_Fn1>(__f1), std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...));
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}
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};
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template <class _Fn1, class _Fn2>
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struct __compose_t : __perfect_forward<__compose_op, _Fn1, _Fn2> {
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using __perfect_forward<__compose_op, _Fn1, _Fn2>::__perfect_forward;
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};
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template <class _Fn1, class _Fn2>
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_LIBCPP_HIDE_FROM_ABI constexpr auto __compose(_Fn1&& __f1, _Fn2&& __f2) noexcept(
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noexcept(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2))))
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-> decltype(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2))) {
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return __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2));
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}
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___FUNCTIONAL_COMPOSE_H
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