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Sprout/sprout/algorithm/fixed/shuffle.hpp
2016-02-25 18:48:28 +09:00

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4.4 KiB
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/*=============================================================================
Copyright (c) 2011-2016 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP
#define SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/index_tuple/metafunction.hpp>
#include <sprout/array/array.hpp>
#include <sprout/pit/pit.hpp>
#include <sprout/container/traits.hpp>
#include <sprout/container/functions.hpp>
#include <sprout/container/indexes.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/utility/forward.hpp>
#include <sprout/algorithm/fixed/results.hpp>
#include <sprout/algorithm/fixed/swap_element.hpp>
#include <sprout/numeric/fixed/iota.hpp>
#include <sprout/random/results.hpp>
#include <sprout/workaround/detail/uniform_int_distribution.hpp>
namespace sprout {
namespace fixed {
namespace detail {
template<std::size_t N, typename Random>
inline SPROUT_CONSTEXPR sprout::array<std::ptrdiff_t, N>
make_shuffle_indexes_1(std::ptrdiff_t n, Random const& rnd, sprout::array<std::ptrdiff_t, N> const& arr, std::ptrdiff_t i) {
return i < n - 1
? sprout::fixed::detail::make_shuffle_indexes_1(
n,
sprout::random::next(rnd)(),
sprout::fixed::swap_element(arr, arr.begin() + i, arr.begin() + sprout::random::result(rnd)),
i + 1
)
: sprout::fixed::swap_element(arr, arr.begin() + i, arr.begin() + sprout::random::result(rnd))
;
}
template<std::size_t N, typename UniformRandomNumberGenerator>
inline SPROUT_CONSTEXPR sprout::array<std::ptrdiff_t, N>
make_shuffle_indexes(std::ptrdiff_t n, UniformRandomNumberGenerator&& g) {
return n > 1
? sprout::fixed::detail::make_shuffle_indexes_1(
n,
SPROUT_WORKAROUND_DETAIL_UNIFORM_INT_DISTRIBUTION<std::ptrdiff_t>(0, n - 1)(
SPROUT_FORWARD(UniformRandomNumberGenerator, g)
),
sprout::fixed::iota(sprout::pit<sprout::array<std::ptrdiff_t, N> >(), 0),
0
)
: sprout::array<std::ptrdiff_t, N>{{}}
;
}
template<typename Container, typename Shuffled, sprout::index_t... Indexes>
inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
shuffle_impl_1(
Container const& cont,
sprout::index_tuple<Indexes...>,
Shuffled const& shuffled,
typename sprout::container_traits<Container>::difference_type offset,
typename sprout::container_traits<Container>::size_type size
)
{
return sprout::remake<Container>(
cont,
sprout::size(cont),
(Indexes >= offset && Indexes < offset + size
? *sprout::next(sprout::begin(cont), shuffled[Indexes - offset])
: *sprout::next(sprout::internal_begin(cont), Indexes)
)...
);
}
template<typename Container, typename UniformRandomNumberGenerator, sprout::index_t... Indexes>
inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
shuffle_impl(
Container const& cont,
sprout::index_tuple<Indexes...> indexes,
UniformRandomNumberGenerator&& g,
typename sprout::container_traits<Container>::difference_type offset,
typename sprout::container_traits<Container>::size_type size
)
{
return sprout::fixed::detail::shuffle_impl_1(
cont,
indexes,
sprout::fixed::detail::make_shuffle_indexes<sprout::container_traits<Container>::static_size>(
size,
SPROUT_FORWARD(UniformRandomNumberGenerator, g)
),
offset,
size
);
}
} // namespace detail
//
// shuffle
//
template<typename Container, typename UniformRandomNumberGenerator>
inline SPROUT_CONSTEXPR typename sprout::fixed::results::algorithm<Container>::type
shuffle(Container const& cont, UniformRandomNumberGenerator&& g) {
return sprout::fixed::detail::shuffle_impl(
cont,
sprout::container_indexes<Container>::make(),
SPROUT_FORWARD(UniformRandomNumberGenerator, g),
sprout::internal_begin_offset(cont),
sprout::size(cont)
);
}
} // namespace fixed
using sprout::fixed::shuffle;
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_FIXED_SHUFFLE_HPP