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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
#define _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
#include <__concepts/same_as.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/invoke.h>
#include <__type_traits/decay.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/integral_constant.h>
#include <__type_traits/is_member_pointer.h>
#include <__type_traits/is_same.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Pred, class _Proj>
struct _ProjectedPred {
_Pred& __pred; // Can be a unary or a binary predicate.
_Proj& __proj;
_LIBCPP_CONSTEXPR _ProjectedPred(_Pred& __pred_arg, _Proj& __proj_arg) : __pred(__pred_arg), __proj(__proj_arg) {}
template <class _Tp>
typename __invoke_of<_Pred&,
decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_Tp>()))
>::type
_LIBCPP_CONSTEXPR operator()(_Tp&& __v) const {
return std::__invoke(__pred, std::__invoke(__proj, std::forward<_Tp>(__v)));
}
template <class _T1, class _T2>
typename __invoke_of<_Pred&,
decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T1>())),
decltype(std::__invoke(std::declval<_Proj&>(), std::declval<_T2>()))
>::type
_LIBCPP_CONSTEXPR operator()(_T1&& __lhs, _T2&& __rhs) const {
return std::__invoke(__pred,
std::__invoke(__proj, std::forward<_T1>(__lhs)),
std::__invoke(__proj, std::forward<_T2>(__rhs)));
}
};
template <class _Pred, class _Proj, class = void>
struct __can_use_pristine_comp : false_type {};
template <class _Pred, class _Proj>
struct __can_use_pristine_comp<_Pred, _Proj, __enable_if_t<
!is_member_pointer<typename decay<_Pred>::type>::value && (
#if _LIBCPP_STD_VER > 17
is_same<typename decay<_Proj>::type, identity>::value ||
#endif
is_same<typename decay<_Proj>::type, __identity>::value
)
> > : true_type {};
template <class _Pred, class _Proj>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR static
__enable_if_t<
!__can_use_pristine_comp<_Pred, _Proj>::value,
_ProjectedPred<_Pred, _Proj>
>
__make_projected(_Pred& __pred, _Proj& __proj) {
return _ProjectedPred<_Pred, _Proj>(__pred, __proj);
}
// Avoid creating the functor and just use the pristine comparator -- for certain algorithms, this would enable
// optimizations that rely on the type of the comparator. Additionally, this results in less layers of indirection in
// the call stack when the comparator is invoked, even in an unoptimized build.
template <class _Pred, class _Proj>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR static
__enable_if_t<
__can_use_pristine_comp<_Pred, _Proj>::value,
_Pred&
>
__make_projected(_Pred& __pred, _Proj&) {
return __pred;
}
_LIBCPP_END_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
_LIBCPP_BEGIN_NAMESPACE_STD
namespace ranges {
template <class _Comp, class _Proj1, class _Proj2>
_LIBCPP_HIDE_FROM_ABI constexpr static
decltype(auto) __make_projected_comp(_Comp& __comp, _Proj1& __proj1, _Proj2& __proj2) {
if constexpr (same_as<decay_t<_Proj1>, identity> && same_as<decay_t<_Proj2>, identity> &&
!is_member_pointer_v<decay_t<_Comp>>) {
// Avoid creating the lambda and just use the pristine comparator -- for certain algorithms, this would enable
// optimizations that rely on the type of the comparator.
return __comp;
} else {
return [&](auto&& __lhs, auto&& __rhs) {
return std::invoke(__comp,
std::invoke(__proj1, std::forward<decltype(__lhs)>(__lhs)),
std::invoke(__proj2, std::forward<decltype(__rhs)>(__rhs)));
};
}
}
} // namespace ranges
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER > 17
#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
|
