59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
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/*!
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@file
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Defines `boost::hana::repeat`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_REPEAT_HPP
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#define BOOST_HANA_REPEAT_HPP
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#include <boost/hana/fwd/repeat.hpp>
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#include <boost/hana/concept/integral_constant.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <cstddef>
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#include <utility>
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BOOST_HANA_NAMESPACE_BEGIN
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template <typename I, bool condition>
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struct repeat_impl<I, when<condition>> : default_ {
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template <typename F, std::size_t ...i>
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static constexpr void repeat_helper(F&& f, std::index_sequence<i...>) {
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using Swallow = std::size_t[];
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(void)Swallow{0, ((void)f(), i)...};
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}
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template <typename N, typename F>
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static constexpr auto apply(N const&, F&& f) {
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static_assert(N::value >= 0, "hana::repeat(n, f) requires 'n' to be non-negative");
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constexpr std::size_t n = N::value;
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repeat_helper(static_cast<F&&>(f), std::make_index_sequence<n>{});
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}
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};
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//! @cond
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template <typename N, typename F>
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constexpr void repeat_t::operator()(N const& n, F&& f) const {
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using I = typename hana::tag_of<N>::type;
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using Repeat = BOOST_HANA_DISPATCH_IF(repeat_impl<I>,
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hana::IntegralConstant<I>::value
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);
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::IntegralConstant<I>::value,
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"hana::repeat(n, f) requires 'n' to be an IntegralConstant");
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#endif
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return Repeat::apply(n, static_cast<F&&>(f));
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}
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//! @endcond
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_REPEAT_HPP
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