mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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117 lines
4 KiB
C++
117 lines
4 KiB
C++
#ifndef SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP
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#define SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP
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#include <cstddef>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/index_tuple.hpp>
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#include <sprout/array.hpp>
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#include <sprout/pit.hpp>
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#include <sprout/container/traits.hpp>
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#include <sprout/container/functions.hpp>
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#include <sprout/iterator/operation.hpp>
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#include <sprout/utility/forward.hpp>
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#include <sprout/algorithm/fixed/result_of.hpp>
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#include <sprout/algorithm/fixed/swap_element.hpp>
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#include <sprout/numeric/fixed/iota.hpp>
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#include <sprout/random/uniform_int_distribution.hpp>
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namespace sprout {
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namespace fixed {
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namespace detail {
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template<std::size_t N, typename Random>
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inline SPROUT_CONSTEXPR sprout::array<std::ptrdiff_t, N> make_shuffle_indexes_1(
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std::ptrdiff_t n,
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Random const& rnd,
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sprout::array<std::ptrdiff_t, N> const& arr,
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std::ptrdiff_t i
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)
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{
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return i < n - 1
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? sprout::fixed::detail::make_shuffle_indexes_1(
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n,
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rnd(),
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sprout::fixed::swap_element(arr, arr.begin() + i, arr.begin() + rnd.result()),
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i + 1
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)
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: sprout::fixed::swap_element(arr, arr.begin() + i, arr.begin() + rnd.result())
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;
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}
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template<std::size_t N, typename UniformRandomNumberGenerator>
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inline SPROUT_CONSTEXPR sprout::array<std::ptrdiff_t, N> make_shuffle_indexes(
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std::ptrdiff_t n,
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UniformRandomNumberGenerator&& g
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)
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{
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return n > 0
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? sprout::fixed::detail::make_shuffle_indexes_1(
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n,
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sprout::random::uniform_int_distribution<std::ptrdiff_t>(0, n - 1)(sprout::forward<UniformRandomNumberGenerator>(g)),
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sprout::fixed::iota(sprout::pit<sprout::array<std::ptrdiff_t, N> >(), 0),
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0
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)
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: sprout::array<std::ptrdiff_t, N>{{}}
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;
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}
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template<typename Container, typename Shuffled, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type shuffle_impl_1(
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Container const& cont,
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sprout::index_tuple<Indexes...>,
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Shuffled const& shuffled,
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typename sprout::container_traits<Container>::difference_type offset,
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typename sprout::container_traits<Container>::size_type size
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)
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{
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return sprout::remake<Container>(
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cont,
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sprout::size(cont),
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(Indexes >= offset && Indexes < offset + size
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? *sprout::next(sprout::begin(cont), shuffled[Indexes - offset])
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: *sprout::next(sprout::internal_begin(cont), Indexes)
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)...
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);
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}
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template<typename Container, typename UniformRandomNumberGenerator, sprout::index_t... Indexes>
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inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type shuffle_impl(
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Container const& cont,
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sprout::index_tuple<Indexes...> indexes,
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UniformRandomNumberGenerator&& g,
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typename sprout::container_traits<Container>::difference_type offset,
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typename sprout::container_traits<Container>::size_type size
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)
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{
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return sprout::fixed::detail::shuffle_impl_1(
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cont,
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indexes,
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sprout::fixed::detail::make_shuffle_indexes<sprout::container_traits<Container>::static_size>(
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size,
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sprout::forward<UniformRandomNumberGenerator>(g)
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),
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offset,
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size
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);
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}
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} // namespace detail
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//
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// shuffle
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//
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template<typename Container, typename UniformRandomNumberGenerator>
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inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type shuffle(
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Container const& cont,
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UniformRandomNumberGenerator&& g
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)
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{
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return sprout::fixed::detail::shuffle_impl(
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cont,
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typename sprout::index_range<0, sprout::container_traits<Container>::static_size>::type(),
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sprout::forward<UniformRandomNumberGenerator>(g),
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sprout::internal_begin_offset(cont),
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sprout::size(cont)
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);
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}
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} // namespace fixed
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using sprout::fixed::shuffle;
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} // namespace sprout
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#endif // #ifndef SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP
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