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generate_n.hpp
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1
2// Range v3 library
3//
4// Copyright Eric Niebler 2014-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#ifndef RANGES_V3_ALGORITHM_GENERATE_N_HPP
14#define RANGES_V3_ALGORITHM_GENERATE_N_HPP
15
16#include <tuple>
17#include <utility>
18
20
21#include <range/v3/algorithm/result_types.hpp>
28#include <range/v3/utility/static_const.hpp>
29
30#include <range/v3/detail/prologue.hpp>
31
32namespace ranges
33{
36 template<typename O, typename F>
37 using generate_n_result = detail::out_fun_result<O, F>;
38
39 RANGES_FUNC_BEGIN(generate_n)
40
41
42 template(typename O, typename F)(
43 requires invocable<F &> AND output_iterator<O, invoke_result_t<F &>>)
44 constexpr generate_n_result<O, F> //
45 RANGES_FUNC(generate_n)(O first, iter_difference_t<O> n, F fun)
46 {
47 RANGES_EXPECT(n >= 0);
48 auto norig = n;
49 auto b = uncounted(first);
50 for(; 0 != n; ++b, --n)
51 *b = invoke(fun);
52 return {recounted(first, b, norig), detail::move(fun)};
53 }
54
55 RANGES_FUNC_END(generate_n)
56
57 namespace cpp20
58 {
59 using ranges::generate_n;
60 using ranges::generate_n_result;
61 } // namespace cpp20
62 // @}
63} // namespace ranges
64
65#include <range/v3/detail/epilogue.hpp>
66
67#endif
The invocable concept.
The output_iterator concept.