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const.hpp
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1
2// Range v3 library
3//
4// Copyright Eric Niebler 2013-present
5//
6// Use, modification and distribution is subject to the
7// Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at
9// http://www.boost.org/LICENSE_1_0.txt)
10//
11// Project home: https://github.com/ericniebler/range-v3
12//
13
14#ifndef RANGES_V3_VIEW_CONST_HPP
15#define RANGES_V3_VIEW_CONST_HPP
16
17#include <type_traits>
18#include <utility>
19
21
27#include <range/v3/utility/static_const.hpp>
29#include <range/v3/view/all.hpp>
31
32#include <range/v3/detail/prologue.hpp>
33
34namespace ranges
35{
38 template<typename Rng>
39 struct const_view : view_adaptor<const_view<Rng>, Rng>
40 {
41 private:
42 friend range_access;
43 template<bool Const>
44 struct adaptor : adaptor_base
45 {
46 using CRng = meta::const_if_c<Const, Rng>;
47 using value_ = range_value_t<CRng>;
48 using reference_ =
49 common_reference_t<value_ const &&, range_reference_t<CRng>>;
50 using rvalue_reference_ =
51 common_reference_t<value_ const &&, range_rvalue_reference_t<CRng>>;
52 adaptor() = default;
53 template(bool Other)(
54 requires Const && CPP_NOT(Other)) //
55 constexpr adaptor(adaptor<Other>)
56 {}
57 reference_ read(iterator_t<CRng> const & it) const
58 {
59 return *it;
60 }
61 rvalue_reference_ iter_move(iterator_t<CRng> const & it) const
62 noexcept(noexcept(rvalue_reference_(ranges::iter_move(it))))
63 {
64 return ranges::iter_move(it);
65 }
66 };
67 adaptor<simple_view<Rng>()> begin_adaptor()
68 {
69 return {};
70 }
71 CPP_member
72 auto begin_adaptor() const //
73 -> CPP_ret(adaptor<true>)(
74 requires range<Rng const>)
75 {
76 return {};
77 }
78 adaptor<simple_view<Rng>()> end_adaptor()
79 {
80 return {};
81 }
82 CPP_member
83 auto end_adaptor() const //
84 -> CPP_ret(adaptor<true>)(
85 requires range<Rng const>)
86 {
87 return {};
88 }
89
90 public:
91 const_view() = default;
92 explicit const_view(Rng rng)
93 : const_view::view_adaptor{std::move(rng)}
94 {}
95 CPP_auto_member
96 constexpr auto CPP_fun(size)()(
97 requires sized_range<Rng>)
98 {
99 return ranges::size(this->base());
100 }
101 CPP_auto_member
102 constexpr auto CPP_fun(size)()(const
103 requires sized_range<Rng const>)
104 {
105 return ranges::size(this->base());
106 }
107 };
108
109 template<typename Rng>
110 RANGES_INLINE_VAR constexpr bool enable_borrowed_range<const_view<Rng>> = //
111 enable_borrowed_range<Rng>;
112
113#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
114 template<typename Rng>
115 const_view(Rng &&) //
117#endif
118
119 namespace views
120 {
121 struct const_fn
122 {
123 template(typename Rng)(
125 const_view<all_t<Rng>> operator()(Rng && rng) const
126 {
127 return const_view<all_t<Rng>>{all(static_cast<Rng &&>(rng))};
128 }
129 };
130
133 RANGES_INLINE_VARIABLE(view_closure<const_fn>, const_)
134 } // namespace views
136} // namespace ranges
137
138#include <range/v3/detail/epilogue.hpp>
139#include <range/v3/detail/satisfy_boost_range.hpp>
140RANGES_SATISFY_BOOST_RANGE(::ranges::const_view)
141
142#endif
The input_range concept.
The range concept.
The sized_range concept.
The viewable_range concept.
decltype(begin(declval(Rng &))) iterator_t
Definition access.hpp:698
Definition adaptor.hpp:110
Definition const.hpp:40
Definition adaptor.hpp:475
Definition const.hpp:122
Definition view.hpp:178