1*349cc55cSDimitry Andric // -*- C++ -*- 2*349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 3*349cc55cSDimitry Andric // 4*349cc55cSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5*349cc55cSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 6*349cc55cSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7*349cc55cSDimitry Andric // 8*349cc55cSDimitry Andric //===----------------------------------------------------------------------===// 9*349cc55cSDimitry Andric 10*349cc55cSDimitry Andric #ifndef _LIBCPP___FUNCTIONAL_COMPOSE_H 11*349cc55cSDimitry Andric #define _LIBCPP___FUNCTIONAL_COMPOSE_H 12*349cc55cSDimitry Andric 13*349cc55cSDimitry Andric #include <__config> 14*349cc55cSDimitry Andric #include <__functional/invoke.h> 15*349cc55cSDimitry Andric #include <__functional/perfect_forward.h> 16*349cc55cSDimitry Andric #include <__utility/forward.h> 17*349cc55cSDimitry Andric #include <type_traits> 18*349cc55cSDimitry Andric 19*349cc55cSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20*349cc55cSDimitry Andric #pragma GCC system_header 21*349cc55cSDimitry Andric #endif 22*349cc55cSDimitry Andric 23*349cc55cSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 24*349cc55cSDimitry Andric 25*349cc55cSDimitry Andric #if _LIBCPP_STD_VER > 17 26*349cc55cSDimitry Andric 27*349cc55cSDimitry Andric struct __compose_op { 28*349cc55cSDimitry Andric template<class _Fn1, class _Fn2, class ..._Args> 29*349cc55cSDimitry Andric _LIBCPP_HIDE_FROM_ABI 30*349cc55cSDimitry Andric constexpr auto operator()(_Fn1&& __f1, _Fn2&& __f2, _Args&&... __args) const 31*349cc55cSDimitry Andric noexcept(noexcept(_VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...)))) 32*349cc55cSDimitry Andric -> decltype( _VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...))) 33*349cc55cSDimitry Andric { return _VSTD::invoke(_VSTD::forward<_Fn1>(__f1), _VSTD::invoke(_VSTD::forward<_Fn2>(__f2), _VSTD::forward<_Args>(__args)...)); } 34*349cc55cSDimitry Andric }; 35*349cc55cSDimitry Andric 36*349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 37*349cc55cSDimitry Andric struct __compose_t : __perfect_forward<__compose_op, _Fn1, _Fn2> { 38*349cc55cSDimitry Andric using __perfect_forward<__compose_op, _Fn1, _Fn2>::__perfect_forward; 39*349cc55cSDimitry Andric }; 40*349cc55cSDimitry Andric 41*349cc55cSDimitry Andric template <class _Fn1, class _Fn2> 42*349cc55cSDimitry Andric _LIBCPP_HIDE_FROM_ABI 43*349cc55cSDimitry Andric constexpr auto __compose(_Fn1&& __f1, _Fn2&& __f2) 44*349cc55cSDimitry Andric noexcept(noexcept(__compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2)))) 45*349cc55cSDimitry Andric -> decltype( __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2))) 46*349cc55cSDimitry Andric { return __compose_t<decay_t<_Fn1>, decay_t<_Fn2>>(_VSTD::forward<_Fn1>(__f1), _VSTD::forward<_Fn2>(__f2)); } 47*349cc55cSDimitry Andric 48*349cc55cSDimitry Andric #endif // _LIBCPP_STD_VER > 17 49*349cc55cSDimitry Andric 50*349cc55cSDimitry Andric _LIBCPP_END_NAMESPACE_STD 51*349cc55cSDimitry Andric 52*349cc55cSDimitry Andric #endif // _LIBCPP___FUNCTIONAL_COMPOSE_H 53