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take.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_ACTION_TAKE_HPP
15#define RANGES_V3_ACTION_TAKE_HPP
16
18
25#include <range/v3/utility/static_const.hpp>
26
27#include <range/v3/detail/prologue.hpp>
28
29namespace ranges
30{
33 namespace actions
34 {
35 struct take_fn
36 {
37 template(typename Int)(
38 requires detail::integer_like_<Int>)
39 constexpr auto operator()(Int n) const
40 {
41 return make_action_closure(bind_back(take_fn{}, n));
42 }
43
44 template(typename Rng)(
45 requires forward_range<Rng> AND
46 erasable_range<Rng &, iterator_t<Rng>, sentinel_t<Rng>>)
47 Rng operator()(Rng && rng, range_difference_t<Rng> n) const
48 {
49 RANGES_EXPECT(n >= 0);
50 ranges::actions::erase(
51 rng, ranges::next(begin(rng), n, end(rng)), end(rng));
52 return static_cast<Rng &&>(rng);
53 }
54 };
55
57 RANGES_INLINE_VARIABLE(take_fn, take)
58 } // namespace actions
60} // namespace ranges
61
62#include <range/v3/detail/epilogue.hpp>
63
64#endif
The erasable_range concept.
The forward_range concept.
decltype(begin(declval(Rng &))) iterator_t
Definition access.hpp:698
Definition take.hpp:36