1/*!
2@file
3Defines `boost::hana::repeat`.
4
5Copyright Louis Dionne 2013-2022
6Distributed under the Boost Software License, Version 1.0.
7(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
8 */
9
10#ifndef BOOST_HANA_REPEAT_HPP
11#define BOOST_HANA_REPEAT_HPP
12
13#include <boost/hana/fwd/repeat.hpp>
14
15#include <boost/hana/concept/integral_constant.hpp>
16#include <boost/hana/config.hpp>
17#include <boost/hana/core/dispatch.hpp>
18
19#include <cstddef>
20#include <utility>
21
22
23namespace boost { namespace hana {
24 template <typename I, bool condition>
25 struct repeat_impl<I, when<condition>> : default_ {
26 template <typename F, std::size_t ...i>
27 static constexpr void repeat_helper(F&& f, std::index_sequence<i...>) {
28 using Swallow = std::size_t[];
29 (void)Swallow{0, ((void)f(), i)...};
30 }
31
32 template <typename N, typename F>
33 static constexpr auto apply(N const&, F&& f) {
34 static_assert(N::value >= 0, "hana::repeat(n, f) requires 'n' to be non-negative");
35 constexpr std::size_t n = N::value;
36 repeat_helper(static_cast<F&&>(f), std::make_index_sequence<n>{});
37 }
38 };
39
40 //! @cond
41 template <typename N, typename F>
42 constexpr void repeat_t::operator()(N const& n, F&& f) const {
43 using I = typename hana::tag_of<N>::type;
44 using Repeat = BOOST_HANA_DISPATCH_IF(repeat_impl<I>,
45 hana::IntegralConstant<I>::value
46 );
47
48 #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
49 static_assert(hana::IntegralConstant<I>::value,
50 "hana::repeat(n, f) requires 'n' to be an IntegralConstant");
51 #endif
52
53 return Repeat::apply(n, static_cast<F&&>(f));
54 }
55 //! @endcond
56}} // end namespace boost::hana
57
58#endif // !BOOST_HANA_REPEAT_HPP
59

source code of boost/libs/hana/include/boost/hana/repeat.hpp