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-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___RANGES_ISTREAM_VIEW_H 11 #define _LIBCPP___RANGES_ISTREAM_VIEW_H 12 13 #include <__concepts/constructible.h> 14 #include <__concepts/derived_from.h> 15 #include <__concepts/movable.h> 16 #include <__config> 17 #include <__iterator/default_sentinel.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__memory/addressof.h> 20 #include <__ranges/view_interface.h> 21 #include <__type_traits/remove_cvref.h> 22 #include <__utility/forward.h> 23 #include <cstddef> 24 #include <iosfwd> 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 # pragma GCC system_header 28 #endif 29 30 #if _LIBCPP_STD_VER >= 20 31 32 _LIBCPP_BEGIN_NAMESPACE_STD 33 34 namespace ranges { 35 36 template <class _Val, class _CharT, class _Traits> 37 concept __stream_extractable = requires(basic_istream<_CharT, _Traits>& __is, _Val& __t) { __is >> __t; }; 38 39 template <movable _Val, class _CharT, class _Traits = char_traits<_CharT>> 40 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits> 41 class basic_istream_view : public view_interface<basic_istream_view<_Val, _CharT, _Traits>> { 42 class __iterator; 43 44 public: 45 _LIBCPP_HIDE_FROM_ABI constexpr explicit basic_istream_view(basic_istream<_CharT, _Traits>& __stream) 46 : __stream_(std::addressof(__stream)) {} 47 48 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() { 49 *__stream_ >> __value_; 50 return __iterator{*this}; 51 } 52 53 _LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; } 54 55 private: 56 basic_istream<_CharT, _Traits>* __stream_; 57 _LIBCPP_NO_UNIQUE_ADDRESS _Val __value_ = _Val(); 58 }; 59 60 template <movable _Val, class _CharT, class _Traits> 61 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits> 62 class basic_istream_view<_Val, _CharT, _Traits>::__iterator { 63 public: 64 using iterator_concept = input_iterator_tag; 65 using difference_type = ptrdiff_t; 66 using value_type = _Val; 67 68 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator( 69 basic_istream_view<_Val, _CharT, _Traits>& __parent) noexcept 70 : __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 91 private: 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 99 template <class _Val> 100 using istream_view = basic_istream_view<_Val, char>; 101 102 # ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 103 template <class _Val> 104 using wistream_view = basic_istream_view<_Val, wchar_t>; 105 # endif 106 107 namespace views { 108 namespace __istream { 109 110 // clang-format off 111 template <class _Tp> 112 struct __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) const 117 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 on 126 127 } // namespace __istream 128 129 inline namespace __cpo { 130 template <class _Tp> 131 inline constexpr auto istream = __istream::__fn<_Tp>{}; 132 } // namespace __cpo 133 } // namespace views 134 135 } // namespace ranges 136 137 _LIBCPP_END_NAMESPACE_STD 138 139 #endif // _LIBCPP_STD_VER >= 20 140 141 #endif // _LIBCPP___RANGES_ISTREAM_VIEW_H 142