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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___RANGES_ISTREAM_VIEW_H11#define _LIBCPP___RANGES_ISTREAM_VIEW_H12 13#include <__concepts/constructible.h>14#include <__concepts/derived_from.h>15#include <__concepts/movable.h>16#include <__config>17#include <__cstddef/ptrdiff_t.h>18#include <__fwd/istream.h>19#include <__fwd/string.h>20#include <__iterator/default_sentinel.h>21#include <__iterator/iterator_traits.h>22#include <__memory/addressof.h>23#include <__ranges/view_interface.h>24#include <__type_traits/remove_cvref.h>25#include <__utility/forward.h>26 27#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)28# pragma GCC system_header29#endif30 31#if _LIBCPP_STD_VER >= 2032 33_LIBCPP_BEGIN_NAMESPACE_STD34 35namespace ranges {36 37template <class _Val, class _CharT, class _Traits>38concept __stream_extractable = requires(basic_istream<_CharT, _Traits>& __is, _Val& __t) { __is >> __t; };39 40template <movable _Val, class _CharT, class _Traits = char_traits<_CharT>>41 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>42class basic_istream_view : public view_interface<basic_istream_view<_Val, _CharT, _Traits>> {43 class __iterator;44 45public:46 _LIBCPP_HIDE_FROM_ABI constexpr explicit basic_istream_view(basic_istream<_CharT, _Traits>& __stream)47 : __stream_(std::addressof(__stream)) {}48 49 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {50 *__stream_ >> __value_;51 return __iterator{*this};52 }53 54 _LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; }55 56private:57 basic_istream<_CharT, _Traits>* __stream_;58 _LIBCPP_NO_UNIQUE_ADDRESS _Val __value_ = _Val();59};60 61template <movable _Val, class _CharT, class _Traits>62 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>63class basic_istream_view<_Val, _CharT, _Traits>::__iterator {64public:65 using iterator_concept = input_iterator_tag;66 using difference_type = ptrdiff_t;67 using value_type = _Val;68 69 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(basic_istream_view<_Val, _CharT, _Traits>& __parent) noexcept70 : __parent_(std::addressof(__parent)) {}71 72 __iterator(const __iterator&) = delete;73 _LIBCPP_HIDE_FROM_ABI __iterator(__iterator&&) = default;74 75 __iterator& operator=(const __iterator&) = delete;76 _LIBCPP_HIDE_FROM_ABI __iterator& operator=(__iterator&&) = default;77 78 _LIBCPP_HIDE_FROM_ABI __iterator& operator++() {79 *__parent_->__stream_ >> __parent_->__value_;80 return *this;81 }82 83 _LIBCPP_HIDE_FROM_ABI void operator++(int) { ++*this; }84 85 _LIBCPP_HIDE_FROM_ABI _Val& operator*() const { return __parent_->__value_; }86 87 _LIBCPP_HIDE_FROM_ABI friend bool operator==(const __iterator& __x, default_sentinel_t) {88 return !*__x.__get_parent_stream();89 }90 91private:92 basic_istream_view<_Val, _CharT, _Traits>* __parent_;93 94 _LIBCPP_HIDE_FROM_ABI constexpr basic_istream<_CharT, _Traits>* __get_parent_stream() const {95 return __parent_->__stream_;96 }97};98 99template <class _Val>100using istream_view = basic_istream_view<_Val, char>;101 102# if _LIBCPP_HAS_WIDE_CHARACTERS103template <class _Val>104using wistream_view = basic_istream_view<_Val, wchar_t>;105# endif106 107namespace views {108namespace __istream {109 110// clang-format off111template <class _Tp>112struct __fn {113 template <class _Up, class _UnCVRef = remove_cvref_t<_Up>>114 requires derived_from<_UnCVRef, basic_istream<typename _UnCVRef::char_type,115 typename _UnCVRef::traits_type>>116 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Up&& __u) const117 noexcept(noexcept(basic_istream_view<_Tp, typename _UnCVRef::char_type,118 typename _UnCVRef::traits_type>(std::forward<_Up>(__u))))119 -> decltype( basic_istream_view<_Tp, typename _UnCVRef::char_type,120 typename _UnCVRef::traits_type>(std::forward<_Up>(__u)))121 { return basic_istream_view<_Tp, typename _UnCVRef::char_type,122 typename _UnCVRef::traits_type>(std::forward<_Up>(__u));123 }124};125// clang-format on126 127} // namespace __istream128 129inline namespace __cpo {130template <class _Tp>131inline constexpr auto istream = __istream::__fn<_Tp>{};132} // namespace __cpo133} // namespace views134 135} // namespace ranges136 137_LIBCPP_END_NAMESPACE_STD138 139#endif // _LIBCPP_STD_VER >= 20140 141#endif // _LIBCPP___RANGES_ISTREAM_VIEW_H142