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> 16*06c3fb27SDimitry 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 25*06c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 26349cc55cSDimitry Andric 27349cc55cSDimitry Andric struct __compose_op { 28349cc55cSDimitry Andric template<class _Fn1, class _Fn2, class ..._Args> 29349cc55cSDimitry Andric _LIBCPP_HIDE_FROM_ABI 30349cc55cSDimitry Andric constexpr auto operator()(_Fn1&& __f1, _Fn2&& __f2, _Args&&... __args) const 31349cc55cSDimitry Andric noexcept(noexcept(_VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...)))) 32349cc55cSDimitry Andric -> decltype( _VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...))) 33349cc55cSDimitry Andric { return _VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...)); } 34349cc55cSDimitry Andric }; 35349cc55cSDimitry Andric 36349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 37349cc55cSDimitry Andric struct __compose_t : __perfect_forward<__compose_op, _Fn1, _Fn2> { 38349cc55cSDimitry Andric using __perfect_forward<__compose_op, _Fn1, _Fn2>::__perfect_forward; 39349cc55cSDimitry Andric }; 40349cc55cSDimitry Andric 41349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 42349cc55cSDimitry Andric _LIBCPP_HIDE_FROM_ABI 43349cc55cSDimitry Andric constexpr auto __compose(_Fn1&& __f1, _Fn2&& __f2) 44349cc55cSDimitry Andric noexcept(noexcept(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2)))) 45349cc55cSDimitry Andric -> decltype( __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2))) 46349cc55cSDimitry Andric { return __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2)); } 47349cc55cSDimitry Andric 48*06c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 49349cc55cSDimitry Andric 50349cc55cSDimitry Andric _LIBCPP_END_NAMESPACE_STD 51349cc55cSDimitry Andric 52349cc55cSDimitry Andric #endif // _LIBCPP___FUNCTIONAL_COMPOSE_H 53