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take_while.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_TAKE_WHILE_HPP
15#define RANGES_V3_VIEW_TAKE_WHILE_HPP
16
17#include <type_traits>
18#include <utility>
19
20#include <meta/meta.hpp>
21
23
31#include <range/v3/utility/static_const.hpp>
34
35#include <range/v3/detail/prologue.hpp>
36
37namespace ranges
38{
41 template<typename Rng, typename Pred>
43 : view_adaptor<iter_take_while_view<Rng, Pred>, Rng,
44 is_finite<Rng>::value ? finite : unknown>
45 {
46 private:
47 friend range_access;
48 RANGES_NO_UNIQUE_ADDRESS semiregular_box_t<Pred> pred_;
49
50 template<bool IsConst>
51 struct sentinel_adaptor : adaptor_base
52 {
53 private:
54 friend struct sentinel_adaptor<!IsConst>;
55 using CRng = meta::const_if_c<IsConst, Rng>;
56 RANGES_NO_UNIQUE_ADDRESS semiregular_box_ref_or_val_t<Pred, IsConst> pred_;
57
58 public:
59 sentinel_adaptor() = default;
60 sentinel_adaptor(semiregular_box_ref_or_val_t<Pred, IsConst> pred)
61 : pred_(std::move(pred))
62 {}
63 template(bool Other)(
64 requires IsConst AND CPP_NOT(Other)) //
65 sentinel_adaptor(sentinel_adaptor<Other> that)
66 : pred_(std::move(that.pred_))
67 {}
68 bool empty(iterator_t<CRng> const & it, sentinel_t<CRng> const & last) const
69 {
70 return it == last || !invoke(pred_, it);
71 }
72 };
73 sentinel_adaptor<false> end_adaptor()
74 {
75 return {pred_};
76 }
77 template(bool Const = true)(
78 requires Const AND range<meta::const_if_c<Const, Rng>> AND
79 invocable<Pred const &, iterator_t<meta::const_if_c<Const, Rng>>>)
80 sentinel_adaptor<Const> end_adaptor() const
81 {
82 return {pred_};
83 }
84
85 public:
86 iter_take_while_view() = default;
87 constexpr iter_take_while_view(Rng rng, Pred pred)
88 : iter_take_while_view::view_adaptor{std::move(rng)}
89 , pred_(std::move(pred))
90 {}
91 };
92
93 template<typename Rng, typename Pred>
95 {
96 take_while_view() = default;
97 constexpr take_while_view(Rng rng, Pred pred)
99 indirect(std::move(pred))}
100 {}
101 };
102
103#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
104 template(typename Rng, typename Fun)(
105 requires copy_constructible<Fun>)
106 take_while_view(Rng &&, Fun)
108#endif
109
110 namespace views
111 {
113 {
114 template(typename Rng, typename Pred)(
116 predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
117 constexpr iter_take_while_view<all_t<Rng>, Pred> //
118 operator()(Rng && rng, Pred pred) const
119 {
120 return {all(static_cast<Rng &&>(rng)), std::move(pred)};
121 }
122 };
123
125 {
126 using iter_take_while_base_fn::operator();
127
128 template<typename Pred>
129 constexpr auto operator()(Pred pred) const
130 {
131 return make_view_closure(
132 bind_back(iter_take_while_base_fn{}, std::move(pred)));
133 }
134 };
135
137 {
138 template(typename Rng, typename Pred)(
141 constexpr take_while_view<all_t<Rng>, Pred> //
142 operator()(Rng && rng, Pred pred) const
143 {
144 return {all(static_cast<Rng &&>(rng)), std::move(pred)};
145 }
146 template(typename Rng, typename Pred, typename Proj)(
150 operator()(Rng && rng, Pred pred, Proj proj) const
151 {
152 return {all(static_cast<Rng &&>(rng)),
153 compose(std::move(pred), std::move(proj))};
154 }
155 };
156
158 {
159 template<typename Pred>
160 constexpr auto operator()(Pred pred) const // TODO: underconstrained
161 {
162 return make_view_closure(
163 bind_back(take_while_base_fn{}, std::move(pred)));
164 }
165 template(typename Pred, typename Proj)(
166 requires (!range<Pred>)) // TODO: underconstrained
167 constexpr auto operator()(Pred && pred, Proj proj) const
168
169 {
170 return make_view_closure(bind_back(
171 take_while_base_fn{}, static_cast<Pred &&>(pred), std::move(proj)));
172 }
173 };
174
175 struct RANGES_EMPTY_BASES take_while_fn
177 {
178 using take_while_base_fn::operator();
179 using take_while_bind_fn::operator();
180 };
181
184 RANGES_INLINE_VARIABLE(iter_take_while_fn, iter_take_while)
185
186
188 RANGES_INLINE_VARIABLE(take_while_fn, take_while)
189 } // namespace views
190
191 namespace cpp20
192 {
193 namespace views
194 {
195 using ranges::views::take_while;
196 }
197 template(typename Rng, typename Pred)(
198 requires viewable_range<Rng> AND input_range<Rng> AND
199 predicate<Pred &, iterator_t<Rng>> AND copy_constructible<Pred>)
200 using take_while_view = ranges::take_while_view<Rng, Pred>;
201 } // namespace cpp20
203} // namespace ranges
204
205#include <range/v3/detail/epilogue.hpp>
206#include <range/v3/detail/satisfy_boost_range.hpp>
207RANGES_SATISFY_BOOST_RANGE(::ranges::iter_take_while_view)
208RANGES_SATISFY_BOOST_RANGE(::ranges::take_while_view)
209
210#endif
The indirect_unary_predicate concept.
The input_range concept.
The invocable concept.
The predicate concept.
The range concept.
The viewable_range concept.
decltype(begin(declval(Rng &))) iterator_t
Definition access.hpp:698
Tiny meta-programming library.
Definition adaptor.hpp:110
Definition compose.hpp:33
Definition take_while.hpp:45
Definition take_while.hpp:95
Definition adaptor.hpp:475
CPP_member constexpr auto empty() const noexcept -> CPP_ret(bool)()
Test whether a range can be empty:
Definition interface.hpp:154
Definition take_while.hpp:113
Definition take_while.hpp:125
Definition take_while.hpp:137
Definition take_while.hpp:158
Definition take_while.hpp:177