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1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___ALGORITHM_MAKE_PROJECTED_H10#define _LIBCPP___ALGORITHM_MAKE_PROJECTED_H11 12#include <__config>13#include <__functional/identity.h>14#include <__functional/invoke.h>15#include <__type_traits/decay.h>16#include <__type_traits/enable_if.h>17#include <__type_traits/invoke.h>18#include <__type_traits/is_member_pointer.h>19#include <__utility/declval.h>20#include <__utility/forward.h>21 22#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)23# pragma GCC system_header24#endif25 26_LIBCPP_BEGIN_NAMESPACE_STD27 28template <class _Pred, class _Proj>29struct _ProjectedPred {30 _Pred& __pred; // Can be a unary or a binary predicate.31 _Proj& __proj;32 33 _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI _ProjectedPred(_Pred& __pred_arg, _Proj& __proj_arg)34 : __pred(__pred_arg), __proj(__proj_arg) {}35 36 template <class _Tp>37 __invoke_result_t<_Pred&, decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_Tp>()))> _LIBCPP_CONSTEXPR38 _LIBCPP_HIDE_FROM_ABI39 operator()(_Tp&& __v) const {40 return std::__invoke(__pred, std::__invoke(__proj, std::forward<_Tp>(__v)));41 }42 43 template <class _T1, class _T2>44 __invoke_result_t<_Pred&,45 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T1>())),46 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T2>()))> _LIBCPP_CONSTEXPR47 _LIBCPP_HIDE_FROM_ABI48 operator()(_T1&& __lhs, _T2&& __rhs) const {49 return std::__invoke(50 __pred, std::__invoke(__proj, std::forward<_T1>(__lhs)), std::__invoke(__proj, std::forward<_T2>(__rhs)));51 }52};53 54template <55 class _Pred,56 class _Proj,57 __enable_if_t<!(!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value), int> = 0>58_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ProjectedPred<_Pred, _Proj> __make_projected(_Pred& __pred, _Proj& __proj) {59 return _ProjectedPred<_Pred, _Proj>(__pred, __proj);60}61 62// Avoid creating the functor and just use the pristine comparator -- for certain algorithms, this would enable63// optimizations that rely on the type of the comparator. Additionally, this results in less layers of indirection in64// the call stack when the comparator is invoked, even in an unoptimized build.65template <66 class _Pred,67 class _Proj,68 __enable_if_t<!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value, int> = 0>69_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Pred& __make_projected(_Pred& __pred, _Proj&) {70 return __pred;71}72 73_LIBCPP_END_NAMESPACE_STD74 75#if _LIBCPP_STD_VER >= 2076 77_LIBCPP_BEGIN_NAMESPACE_STD78 79namespace ranges {80 81template <class _Comp, class _Proj1, class _Proj2>82_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) __make_projected_comp(_Comp& __comp, _Proj1& __proj1, _Proj2& __proj2) {83 if constexpr (__is_identity<decay_t<_Proj1>>::value && __is_identity<decay_t<_Proj2>>::value &&84 !is_member_pointer_v<decay_t<_Comp>>) {85 // Avoid creating the lambda and just use the pristine comparator -- for certain algorithms, this would enable86 // optimizations that rely on the type of the comparator.87 return __comp;88 89 } else {90 return [&](auto&& __lhs, auto&& __rhs) -> bool {91 return std::invoke(__comp,92 std::invoke(__proj1, std::forward<decltype(__lhs)>(__lhs)),93 std::invoke(__proj2, std::forward<decltype(__rhs)>(__rhs)));94 };95 }96}97 98} // namespace ranges99 100_LIBCPP_END_NAMESPACE_STD101 102#endif // _LIBCPP_STD_VER >= 20103 104#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H105