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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 _LIBCPP_HIDE_FROM_ABI _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 _LIBCPP_HIDE_FROM_ABI 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 _LIBCPP_HIDE_FROM_ABI 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,
__enable_if_t<!(!is_member_pointer<__decay_t<_Pred> >::value &&
__is_identity<__decay_t<_Proj> >::value),
int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _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,
__enable_if_t<!is_member_pointer<__decay_t<_Pred> >::value &&
__is_identity<__decay_t<_Proj> >::value,
int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Pred& __make_projected(_Pred& __pred, _Proj&) {
return __pred;
}
_LIBCPP_END_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
_LIBCPP_BEGIN_NAMESPACE_STD
namespace ranges {
template <class _Comp, class _Proj1, class _Proj2>
_LIBCPP_HIDE_FROM_ABI constexpr
decltype(auto) __make_projected_comp(_Comp& __comp, _Proj1& __proj1, _Proj2& __proj2) {
if constexpr (__is_identity<decay_t<_Proj1>>::value && __is_identity<decay_t<_Proj2>>::value &&
!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 >= 20
#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
|
