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add C++14 constexpr sample algorithm

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bolero-MURAKAMI 2014-04-05 20:59:19 +09:00
parent 20cd8402b7
commit ac66209e24
2 changed files with 83 additions and 0 deletions
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1
sprout/algorithm/cxx14.hpp
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@ -58,6 +58,7 @@
//#include <sprout/algorithm/cxx14/sort_heap.hpp>
//#include <sprout/algorithm/cxx14/next_permutation.hpp>
//#include <sprout/algorithm/cxx14/prev_permutation.hpp>
#include <sprout/algorithm/cxx14/sample.hpp>
//#include <sprout/algorithm/cxx14/copy_while.hpp>
//#include <sprout/algorithm/cxx14/copy_until.hpp>
//#include <sprout/algorithm/cxx14/clamp_range.hpp>

82
sprout/algorithm/cxx14/sample.hpp Normal file
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@ -0,0 +1,82 @@
/*=============================================================================
Copyright (c) 2011-2014 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_CXX14_SAMPLE_HPP
#define SPROUT_ALGORITHM_CXX14_SAMPLE_HPP
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/utility/forward.hpp>
#include <sprout/iterator/distance.hpp>
#include <sprout/workaround/detail/uniform_int_distribution.hpp>
#include HDR_ALGORITHM_MIN_MAX_SSCRISK_CEL_OR_SPROUT
namespace sprout {
namespace detail {
template<typename PopIterator, typename SampleIterator, typename Size, typename URNG>
inline SPROUT_CXX14_CONSTEXPR SampleIterator
sample_impl(
PopIterator first, PopIterator last, std::input_iterator_tag*,
SampleIterator out, std::random_access_iterator_tag*,
Size n, URNG&& g
)
{
typedef SPROUT_WORKAROUND_DETAIL_UNIFORM_INT_DISTRIBUTION<Size> distribution_type;
typedef typename distribution_type::param_type param_type;
distribution_type dist = {};
Size sample_size = 0;
while (first != last && sample_size != n) {
out[sample_size++] = *first++;
}
for (Size pop_size = sample_size; first != last; ++first, ++pop_size) {
param_type const p(0, pop_size);
Size const k = dist(g, p);
if (k < n) {
out[k] = *first;
}
}
return out + sample_size;
}
template<typename PopIterator, typename SampleIterator, typename Size, typename URNG>
inline SPROUT_CXX14_CONSTEXPR SampleIterator
sample_impl(
PopIterator first, PopIterator last, std::forward_iterator_tag*,
SampleIterator out, std::output_iterator_tag*,
Size n, URNG&& g
)
{
typedef SPROUT_WORKAROUND_DETAIL_UNIFORM_INT_DISTRIBUTION<Size> distribution_type;
typedef typename distribution_type::param_type param_type;
distribution_type dist = {};
Size unsampled_size = sprout::distance(first, last);
for (n = NS_SSCRISK_CEL_OR_SPROUT::min(n, unsampled_size); n != 0; ++first ) {
param_type const p(0, --unsampled_size);
if (dist(g, p) < n) {
*out++ = *first;
--n;
}
}
return out;
}
} // namespace detail
//
// sample
//
template<typename PopIterator, typename SampleIterator, typename Size, typename URNG>
inline SPROUT_CXX14_CONSTEXPR SampleIterator
sample(PopIterator first, PopIterator last, SampleIterator out, Size n, URNG&& g) {
typedef typename std::iterator_traits<PopIterator>::iterator_category* pop_category;
typedef typename std::iterator_traits<SampleIterator>::iterator_category* sample_category;
return sprout::detail::sample_impl(
first, last, pop_category(),
out, sample_category(),
n, SPROUT_FORWARD(URNG, g)
);
}
} // namespace sprout
#endif // #ifndef SPROUT_ALGORITHM_CXX14_SAMPLE_HPP