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 <__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_header
29#endif
30
31#if _LIBCPP_STD_VER >= 20
32
33_LIBCPP_BEGIN_NAMESPACE_STD
34
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) 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
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_CHARACTERS
103template <class _Val>
104using wistream_view = basic_istream_view<_Val, wchar_t>;
105# endif
106
107namespace views {
108namespace __istream {
109
110// clang-format off
111template <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) 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
129inline namespace __cpo {
130template <class _Tp>
131inline 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