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take_while.hpp
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1 // 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 
22 #include <range/v3/range_fwd.hpp>
23 
31 #include <range/v3/utility/static_const.hpp>
33 #include <range/v3/view/view.hpp>
34 
35 #include <range/v3/detail/prologue.hpp>
36 
37 namespace 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)(
115  requires viewable_range<Rng> AND input_range<Rng> AND
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)(
139  requires viewable_range<Rng> AND input_range<Rng> AND
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)(
147  requires viewable_range<Rng> AND input_range<Rng> AND
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 
185 
186 
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>
207 RANGES_SATISFY_BOOST_RANGE(::ranges::iter_take_while_view)
208 RANGES_SATISFY_BOOST_RANGE(::ranges::take_while_view)
209 
210 #endif
CPP_concept invocable
\concept invocable
Definition: concepts.hpp:48
CPP_concept predicate
\concept predicate
Definition: concepts.hpp:73
CPP_concept indirect_unary_predicate
\concept indirect_unary_predicate
Definition: concepts.hpp:632
CPP_concept range
\concept range
Definition: concepts.hpp:69
decltype(begin(declval(Rng &))) iterator_t
Definition: access.hpp:698
RANGES_INLINE_VARIABLE(detail::to_container_fn< detail::from_range< std::vector >>, to_vector) template< template< typename... > class ContT > auto to(RANGES_HIDDEN_DETAIL(detail
For initializing a container of the specified type with the elements of an Range.
Definition: conversion.hpp:399
typename Fn::template invoke< Args... > invoke
Evaluate the invocable Fn with the arguments Args.
Definition: meta.hpp:541
defer< bind_back, Fn, Ts... > bind_back
Definition: meta.hpp:994
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
constexpr CPP_member auto empty() const noexcept -> CPP_ret(bool)(requires(detail::has_fixed_size_< Cardinality >))
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