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-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
10#define _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
11
12#include <__concepts/same_as.h>
13#include <__config>
14#include <__functional/identity.h>
15#include <__functional/invoke.h>
16#include <__type_traits/decay.h>
17#include <__type_traits/enable_if.h>
18#include <__type_traits/integral_constant.h>
19#include <__type_traits/is_member_pointer.h>
20#include <__type_traits/is_same.h>
21#include <__utility/declval.h>
22#include <__utility/forward.h>
23
24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25# pragma GCC system_header
26#endif
27
28_LIBCPP_BEGIN_NAMESPACE_STD
29
30template <class _Pred, class _Proj>
31struct _ProjectedPred {
32 _Pred& __pred; // Can be a unary or a binary predicate.
33 _Proj& __proj;
34
35 _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI _ProjectedPred(_Pred& __pred_arg, _Proj& __proj_arg)
36 : __pred(__pred_arg), __proj(__proj_arg) {}
37
38 template <class _Tp>
39 typename __invoke_of<_Pred&, decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_Tp>()))>::type
40 _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI
41 operator()(_Tp&& __v) const {
42 return std::__invoke(__pred, std::__invoke(__proj, std::forward<_Tp>(__v)));
43 }
44
45 template <class _T1, class _T2>
46 typename __invoke_of<_Pred&,
47 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T1>())),
48 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T2>()))>::type _LIBCPP_CONSTEXPR
49 _LIBCPP_HIDE_FROM_ABI
50 operator()(_T1&& __lhs, _T2&& __rhs) const {
51 return std::__invoke(
52 __pred, std::__invoke(__proj, std::forward<_T1>(__lhs)), std::__invoke(__proj, std::forward<_T2>(__rhs)));
53 }
54};
55
56template <
57 class _Pred,
58 class _Proj,
59 __enable_if_t<!(!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value), int> = 0>
60_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ProjectedPred<_Pred, _Proj> __make_projected(_Pred& __pred, _Proj& __proj) {
61 return _ProjectedPred<_Pred, _Proj>(__pred, __proj);
62}
63
64// Avoid creating the functor and just use the pristine comparator -- for certain algorithms, this would enable
65// optimizations that rely on the type of the comparator. Additionally, this results in less layers of indirection in
66// the call stack when the comparator is invoked, even in an unoptimized build.
67template <
68 class _Pred,
69 class _Proj,
70 __enable_if_t<!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value, int> = 0>
71_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Pred& __make_projected(_Pred& __pred, _Proj&) {
72 return __pred;
73}
74
75_LIBCPP_END_NAMESPACE_STD
76
77#if _LIBCPP_STD_VER >= 20
78
79_LIBCPP_BEGIN_NAMESPACE_STD
80
81namespace ranges {
82
83template <class _Comp, class _Proj1, class _Proj2>
84_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) __make_projected_comp(_Comp& __comp, _Proj1& __proj1, _Proj2& __proj2) {
85 if constexpr (__is_identity<decay_t<_Proj1>>::value && __is_identity<decay_t<_Proj2>>::value &&
86 !is_member_pointer_v<decay_t<_Comp>>) {
87 // Avoid creating the lambda and just use the pristine comparator -- for certain algorithms, this would enable
88 // optimizations that rely on the type of the comparator.
89 return __comp;
90
91 } else {
92 return [&](auto&& __lhs, auto&& __rhs) -> bool {
93 return std::invoke(__comp,
94 std::invoke(__proj1, std::forward<decltype(__lhs)>(__lhs)),
95 std::invoke(__proj2, std::forward<decltype(__rhs)>(__rhs)));
96 };
97 }
98}
99
100} // namespace ranges
101
102_LIBCPP_END_NAMESPACE_STD
103
104#endif // _LIBCPP_STD_VER >= 20
105
106#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
107