Horizon
stride.hpp
Go to the documentation of this file.
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_STRIDE_HPP
15 #define RANGES_V3_ACTION_STRIDE_HPP
16 
17 #include <range/v3/range_fwd.hpp>
18 
25 #include <range/v3/utility/static_const.hpp>
26 
27 #include <range/v3/detail/prologue.hpp>
28 
29 namespace ranges
30 {
33  namespace actions
34  {
35  struct stride_fn
36  {
37  template(typename D)(
38  requires detail::integer_like_<D>)
39  constexpr auto operator()(D step) const
40  {
41  return make_action_closure(bind_back(stride_fn{}, step));
42  }
43 
44  template(typename Rng, typename D = range_difference_t<Rng>)(
45  requires forward_range<Rng> AND
46  erasable_range<Rng &, iterator_t<Rng>, sentinel_t<Rng>> AND
48  Rng operator()(Rng && rng, range_difference_t<Rng> const step) const
49  {
50  using I = iterator_t<Rng>;
51  using S = sentinel_t<Rng>;
52  RANGES_EXPECT(0 < step);
53  if(1 < step)
54  {
55  I first = ranges::begin(rng);
56  S const last = ranges::end(rng);
57  if(first != last)
58  {
59  for(I i = ranges::next(++first, step - 1, last); i != last;
60  advance(i, step, last), ++first)
61  {
62  *first = iter_move(i);
63  }
64  }
65  ranges::actions::erase(rng, first, last);
66  }
67  return static_cast<Rng &&>(rng);
68  }
69  };
70 
73  } // namespace actions
75 } // namespace ranges
76 
77 #include <range/v3/detail/epilogue.hpp>
78 
79 #endif
CPP_concept permutable
\concept permutable
Definition: concepts.hpp:840
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
CPP_concept erasable_range
\concept erasable_range
Definition: erase.hpp:76
defer< bind_back, Fn, Ts... > bind_back
Definition: meta.hpp:994
front< Pair > first
Retrieve the first element of the pair Pair.
Definition: meta.hpp:2251
Definition: stride.hpp:36