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___CXX03___ALGORITHM_MAKE_PROJECTED_H
10 #define _LIBCPP___CXX03___ALGORITHM_MAKE_PROJECTED_H
11
12 #include <__cxx03/__config>
13 #include <__cxx03/__functional/identity.h>
14 #include <__cxx03/__type_traits/decay.h>
15 #include <__cxx03/__type_traits/enable_if.h>
16 #include <__cxx03/__type_traits/integral_constant.h>
17 #include <__cxx03/__type_traits/invoke.h>
18 #include <__cxx03/__type_traits/is_member_pointer.h>
19 #include <__cxx03/__type_traits/is_same.h>
20 #include <__cxx03/__utility/declval.h>
21 #include <__cxx03/__utility/forward.h>
22
23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24 # pragma GCC system_header
25 #endif
26
27 _LIBCPP_BEGIN_NAMESPACE_STD
28
29 template <class _Pred, class _Proj>
30 struct _ProjectedPred {
31 _Pred& __pred; // Can be a unary or a binary predicate.
32 _Proj& __proj;
33
_ProjectedPred_ProjectedPred34 _LIBCPP_HIDE_FROM_ABI _ProjectedPred(_Pred& __pred_arg, _Proj& __proj_arg) : __pred(__pred_arg), __proj(__proj_arg) {}
35
36 template <class _Tp>
37 typename __invoke_of<_Pred&, decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_Tp>()))>::type
38 _LIBCPP_HIDE_FROM_ABI
operator_ProjectedPred39 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 typename __invoke_of<_Pred&,
45 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T1>())),
46 decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T2>()))>::type _LIBCPP_HIDE_FROM_ABI
operator_ProjectedPred47 operator()(_T1&& __lhs, _T2&& __rhs) const {
48 return std::__invoke(
49 __pred, std::__invoke(__proj, std::forward<_T1>(__lhs)), std::__invoke(__proj, std::forward<_T2>(__rhs)));
50 }
51 };
52
53 template <
54 class _Pred,
55 class _Proj,
56 __enable_if_t<!(!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value), int> = 0>
__make_projected(_Pred & __pred,_Proj & __proj)57 _LIBCPP_HIDE_FROM_ABI _ProjectedPred<_Pred, _Proj> __make_projected(_Pred& __pred, _Proj& __proj) {
58 return _ProjectedPred<_Pred, _Proj>(__pred, __proj);
59 }
60
61 // Avoid creating the functor and just use the pristine comparator -- for certain algorithms, this would enable
62 // optimizations that rely on the type of the comparator. Additionally, this results in less layers of indirection in
63 // the call stack when the comparator is invoked, even in an unoptimized build.
64 template <
65 class _Pred,
66 class _Proj,
67 __enable_if_t<!is_member_pointer<__decay_t<_Pred> >::value && __is_identity<__decay_t<_Proj> >::value, int> = 0>
__make_projected(_Pred & __pred,_Proj &)68 _LIBCPP_HIDE_FROM_ABI _Pred& __make_projected(_Pred& __pred, _Proj&) {
69 return __pred;
70 }
71
72 _LIBCPP_END_NAMESPACE_STD
73
74 #endif // _LIBCPP___CXX03___ALGORITHM_MAKE_PROJECTED_H
75