1349cc55cSDimitry Andric // -*- C++ -*- 2349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 3349cc55cSDimitry Andric // 4349cc55cSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5349cc55cSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 6349cc55cSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7349cc55cSDimitry Andric // 8349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 9349cc55cSDimitry Andric 10349cc55cSDimitry Andric #ifndef _LIBCPP___FUNCTIONAL_COMPOSE_H 11349cc55cSDimitry Andric #define _LIBCPP___FUNCTIONAL_COMPOSE_H 12349cc55cSDimitry Andric 13349cc55cSDimitry Andric #include <__config> 14349cc55cSDimitry Andric #include <__functional/invoke.h> 15349cc55cSDimitry Andric #include <__functional/perfect_forward.h> 1606c3fb27SDimitry Andric #include <__type_traits/decay.h> 17349cc55cSDimitry Andric #include <__utility/forward.h> 18349cc55cSDimitry Andric 19349cc55cSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20349cc55cSDimitry Andric # pragma GCC system_header 21349cc55cSDimitry Andric #endif 22349cc55cSDimitry Andric 23349cc55cSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 24349cc55cSDimitry Andric 2506c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 26349cc55cSDimitry Andric 27349cc55cSDimitry Andric struct __compose_op { 28349cc55cSDimitry Andric template <class _Fn1, class _Fn2, class... _Args> 29*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Fn1&& __f1, _Fn2&& __f2, _Args&&... __args) const noexcept(noexcept( 30*cb14a3feSDimitry Andric std::invoke(std::forward<_Fn1>(__f1), std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...)))) 31*cb14a3feSDimitry Andric -> decltype(std::invoke(std::forward<_Fn1>(__f1), 32*cb14a3feSDimitry Andric std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...))) { 33*cb14a3feSDimitry Andric return std::invoke(std::forward<_Fn1>(__f1), std::invoke(std::forward<_Fn2>(__f2), std::forward<_Args>(__args)...)); 34*cb14a3feSDimitry Andric } 35349cc55cSDimitry Andric }; 36349cc55cSDimitry Andric 37349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 38349cc55cSDimitry Andric struct __compose_t : __perfect_forward<__compose_op, _Fn1, _Fn2> { 39349cc55cSDimitry Andric using __perfect_forward<__compose_op, _Fn1, _Fn2>::__perfect_forward; 40349cc55cSDimitry Andric }; 41349cc55cSDimitry Andric 42349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 43*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr auto __compose(_Fn1&& __f1, _Fn2&& __f2) noexcept( 44*cb14a3feSDimitry Andric noexcept(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2)))) 45*cb14a3feSDimitry Andric -> decltype(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2))) { 46*cb14a3feSDimitry Andric return __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(std::forward<_Fn1>(__f1), std::forward<_Fn2>(__f2)); 47*cb14a3feSDimitry Andric } 48349cc55cSDimitry Andric 4906c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 50349cc55cSDimitry Andric 51349cc55cSDimitry Andric _LIBCPP_END_NAMESPACE_STD 52349cc55cSDimitry Andric 53349cc55cSDimitry Andric #endif // _LIBCPP___FUNCTIONAL_COMPOSE_H 54