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slice.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_ACTION_SLICE_HPP
15 #define RANGES_V3_ACTION_SLICE_HPP
16 
17 #include <meta/meta.hpp>
18 
19 #include <range/v3/range_fwd.hpp>
20 
27 #include <range/v3/utility/static_const.hpp>
29 
30 #include <range/v3/detail/prologue.hpp>
31 
32 namespace ranges
33 {
36  namespace actions
37  {
38  struct slice_fn
39  {
40  private:
41  template<typename D>
42  using diff_t = range_difference_t<D>;
43 
44  public:
45  // Overloads for the pipe syntax: rng | actions::slice(from, to)
46  template(typename D)(
47  requires integral<D>)
48  constexpr auto operator()(D from, D to) const
49  {
50  return make_action_closure(bind_back(slice_fn{}, from, to));
51  }
52  template(typename D)(
53  requires integral<D>)
54  constexpr auto operator()(D from, detail::from_end_<D> to) const
55  {
56  return make_action_closure(bind_back(slice_fn{}, from, to));
57  }
58  template(typename D)(
59  requires integral<D>)
60  constexpr auto operator()(detail::from_end_<D> from, detail::from_end_<D> to)
61  const
62  {
63  return make_action_closure(bind_back(slice_fn{}, from, to));
64  }
65  template(typename D)(
66  requires integral<D>)
67  constexpr auto operator()(D from, end_fn const & to) const
68  {
69  return make_action_closure(bind_back(slice_fn{}, from, to));
70  }
71  template(typename D)(
72  requires integral<D>)
73  constexpr auto operator()(detail::from_end_<D> from, end_fn const & to) const
74  {
75  return make_action_closure(bind_back(slice_fn{}, from, to));
76  }
77 
78  template(typename Rng, typename I = iterator_t<Rng>)(
79  requires forward_range<Rng> AND erasable_range<Rng &, I, I>)
80  Rng operator()(Rng && rng, diff_t<Rng> from, diff_t<Rng> to) const
81  {
82  RANGES_EXPECT(0 <= from && 0 <= to && from <= to);
83  RANGES_EXPECT(!sized_range<Rng> || to <= distance(rng));
84  ranges::actions::erase(rng, begin(rng), next(begin(rng), from));
85  ranges::actions::erase(rng, next(begin(rng), to - from), end(rng));
86  return static_cast<Rng &&>(rng);
87  }
88 
89  template(typename Rng, typename I = iterator_t<Rng>)(
90  requires bidirectional_range<Rng> AND erasable_range<Rng &, I, I>)
91  Rng operator()(Rng && rng,
92  diff_t<Rng> from,
93  detail::from_end_<diff_t<Rng>> to) const
94  {
95  RANGES_EXPECT(0 <= from && to.dist_ <= 0);
96  RANGES_EXPECT(!sized_range<Rng> || from - to.dist_ <= distance(rng));
97  ranges::actions::erase(rng, begin(rng), next(begin(rng), from));
98  if(to.dist_ != 0)
99  {
100  auto const last = next(begin(rng), end(rng));
101  ranges::actions::erase(rng, prev(last, -to.dist_), last);
102  }
103  return static_cast<Rng &&>(rng);
104  }
105 
106  template(typename Rng, typename I = iterator_t<Rng>)(
107  requires bidirectional_range<Rng> AND erasable_range<Rng &, I, I>)
108  Rng operator()(Rng && rng,
109  detail::from_end_<diff_t<Rng>> from,
110  detail::from_end_<diff_t<Rng>> to) const
111  {
112  RANGES_EXPECT(from.dist_ <= 0 && to.dist_ <= 0 && from.dist_ <= to.dist_);
113  RANGES_EXPECT(!sized_range<Rng> || 0 <= distance(rng) + from.dist_);
114  auto last = next(begin(rng), end(rng));
115  ranges::actions::erase(rng, prev(last, -to.dist_), last);
116  last = next(begin(rng), end(rng));
117  ranges::actions::erase(
118  rng, begin(rng), prev(last, to.dist_ - from.dist_));
119  return static_cast<Rng &&>(rng);
120  }
121 
122  template(typename Rng, typename I = iterator_t<Rng>)(
123  requires forward_range<Rng> AND erasable_range<Rng &, I, I>)
124  Rng operator()(Rng && rng, diff_t<Rng> from, end_fn const &) const
125  {
126  RANGES_EXPECT(0 <= from);
127  RANGES_EXPECT(!sized_range<Rng> || from <= distance(rng));
128  ranges::actions::erase(rng, begin(rng), next(begin(rng), from));
129  return static_cast<Rng &&>(rng);
130  }
131 
132  template(typename Rng, typename I = iterator_t<Rng>)(
133  requires bidirectional_range<Rng> AND erasable_range<Rng &, I, I>)
134  Rng operator()(Rng && rng,
135  detail::from_end_<diff_t<Rng>> from,
136  end_fn const &) const
137  {
138  RANGES_EXPECT(from.dist_ <= 0);
139  RANGES_EXPECT(!sized_range<Rng> || 0 <= distance(rng) + from.dist_);
140  auto const last = next(begin(rng), end(rng));
141  ranges::actions::erase(rng, begin(rng), prev(last, -from.dist_));
142  return static_cast<Rng &&>(rng);
143  }
144  };
145 
148  } // namespace actions
150 } // namespace ranges
151 
152 #include <range/v3/detail/epilogue.hpp>
153 
154 #endif
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
defer< bind_back, Fn, Ts... > bind_back
Definition: meta.hpp:994
Tiny meta-programming library.
Definition: slice.hpp:39