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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___ITERATOR_PROJECTED_H11#define _LIBCPP___ITERATOR_PROJECTED_H12 13#include <__config>14#include <__iterator/concepts.h>15#include <__iterator/incrementable_traits.h> // iter_difference_t16#include <__type_traits/remove_cvref.h>17 18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)19# pragma GCC system_header20#endif21 22_LIBCPP_BEGIN_NAMESPACE_STD23 24#if _LIBCPP_STD_VER >= 2025 26template <class _It, class _Proj>27struct __projected_impl {28 struct __type {29 using __primary_template _LIBCPP_NODEBUG = __type;30 using __projected_iterator _LIBCPP_NODEBUG = _It;31 using __projected_projection _LIBCPP_NODEBUG = _Proj;32 33 using value_type = remove_cvref_t<indirect_result_t<_Proj&, _It>>;34 indirect_result_t<_Proj&, _It> operator*() const; // not defined35 };36};37 38template <weakly_incrementable _It, class _Proj>39struct __projected_impl<_It, _Proj> {40 struct __type {41 using __primary_template _LIBCPP_NODEBUG = __type;42 using __projected_iterator _LIBCPP_NODEBUG = _It;43 using __projected_projection _LIBCPP_NODEBUG = _Proj;44 45 using value_type = remove_cvref_t<indirect_result_t<_Proj&, _It>>;46 using difference_type = iter_difference_t<_It>;47 indirect_result_t<_Proj&, _It> operator*() const; // not defined48 };49};50 51// Note that we implement std::projected in a way that satisfies P2538R1 even in standard52// modes before C++26 to avoid breaking the ABI between standard modes (even though ABI53// breaks with std::projected are expected to have essentially no impact).54template <indirectly_readable _It, indirectly_regular_unary_invocable<_It> _Proj>55using projected = typename __projected_impl<_It, _Proj>::__type;56 57#endif // _LIBCPP_STD_VER >= 2058 59_LIBCPP_END_NAMESPACE_STD60 61#endif // _LIBCPP___ITERATOR_PROJECTED_H62