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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 <__utility/forward.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
_LIBCPP_BEGIN_NAMESPACE_STD
namespace ranges {
template <class _Comp, class _Proj>
_LIBCPP_HIDE_FROM_ABI constexpr static
decltype(auto) __make_projected_comp(_Comp& __comp, _Proj& __proj) {
if constexpr (same_as<_Proj, identity>) {
// 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(__proj, std::forward<decltype(__lhs)>(__lhs)),
std::invoke(__proj, std::forward<decltype(__rhs)>(__rhs)));
};
}
}
} // namespace ranges
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
#endif // _LIBCPP___ALGORITHM_MAKE_PROJECTED_H
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