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 <__fwd/istream.h>
18 #include <__fwd/string.h>
19 #include <__iterator/default_sentinel.h>
20 #include <__iterator/iterator_traits.h>
21 #include <__memory/addressof.h>
22 #include <__ranges/view_interface.h>
23 #include <__type_traits/remove_cvref.h>
24 #include <__utility/forward.h>
25 #include <cstddef>
26
27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28 # pragma GCC system_header
29 #endif
30
31 #if _LIBCPP_STD_VER >= 20
32
33 _LIBCPP_BEGIN_NAMESPACE_STD
34
35 namespace ranges {
36
37 template <class _Val, class _CharT, class _Traits>
requires(basic_istream<_CharT,_Traits> & __is,_Val & __t)38 concept __stream_extractable = requires(basic_istream<_CharT, _Traits>& __is, _Val& __t) { __is >> __t; };
39
40 template <movable _Val, class _CharT, class _Traits = char_traits<_CharT>>
41 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
42 class basic_istream_view : public view_interface<basic_istream_view<_Val, _CharT, _Traits>> {
43 class __iterator;
44
45 public:
basic_istream_view(basic_istream<_CharT,_Traits> & __stream)46 _LIBCPP_HIDE_FROM_ABI constexpr explicit basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
47 : __stream_(std::addressof(__stream)) {}
48
begin()49 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
50 *__stream_ >> __value_;
51 return __iterator{*this};
52 }
53
end()54 _LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; }
55
56 private:
57 basic_istream<_CharT, _Traits>* __stream_;
58 _LIBCPP_NO_UNIQUE_ADDRESS _Val __value_ = _Val();
59 };
60
61 template <movable _Val, class _CharT, class _Traits>
62 requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
63 class basic_istream_view<_Val, _CharT, _Traits>::__iterator {
64 public:
65 using iterator_concept = input_iterator_tag;
66 using difference_type = ptrdiff_t;
67 using value_type = _Val;
68
__iterator(basic_istream_view<_Val,_CharT,_Traits> & __parent)69 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(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
__get_parent_stream()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