138 lines
4.6 KiB
C++
138 lines
4.6 KiB
C++
// <experimental/algorithm> -*- C++ -*-
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// Copyright (C) 2014-2015 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file experimental/algorithm
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* This is a TS C++ Library header.
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*/
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#ifndef _GLIBCXX_EXPERIMENTAL_ALGORITHM
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#define _GLIBCXX_EXPERIMENTAL_ALGORITHM 1
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#pragma GCC system_header
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#if __cplusplus <= 201103L
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# include <bits/c++14_warning.h>
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#else
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#include <algorithm>
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#include <random>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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namespace experimental
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{
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inline namespace fundamentals_v1
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<typename _ForwardIterator, typename _Searcher>
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inline _ForwardIterator
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search(_ForwardIterator __first, _ForwardIterator __last,
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const _Searcher& __searcher)
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{ return __searcher(__first, __last); }
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#define __cpp_lib_experimental_sample 201402
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/// Reservoir sampling algorithm.
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template<typename _InputIterator, typename _RandomAccessIterator,
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typename _Size, typename _UniformRandomNumberGenerator>
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_RandomAccessIterator
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__sample(_InputIterator __first, _InputIterator __last, input_iterator_tag,
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_RandomAccessIterator __out, random_access_iterator_tag,
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_Size __n, _UniformRandomNumberGenerator&& __g)
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{
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using __distrib_type = std::uniform_int_distribution<_Size>;
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using __param_type = typename __distrib_type::param_type;
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__distrib_type __d{};
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_Size __sample_sz = 0;
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while (__first != __last && __sample_sz != __n)
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__out[__sample_sz++] = *__first++;
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for (auto __pop_sz = __sample_sz; __first != __last;
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++__first, ++__pop_sz)
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{
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const auto __k = __d(__g, __param_type{0, __pop_sz});
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if (__k < __n)
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__out[__k] = *__first;
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}
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return __out + __sample_sz;
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}
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/// Selection sampling algorithm.
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template<typename _ForwardIterator, typename _OutputIterator, typename _Cat,
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typename _Size, typename _UniformRandomNumberGenerator>
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_OutputIterator
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__sample(_ForwardIterator __first, _ForwardIterator __last,
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forward_iterator_tag,
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_OutputIterator __out, _Cat,
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_Size __n, _UniformRandomNumberGenerator&& __g)
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{
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using __distrib_type = std::uniform_int_distribution<_Size>;
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using __param_type = typename __distrib_type::param_type;
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__distrib_type __d{};
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_Size __unsampled_sz = std::distance(__first, __last);
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for (__n = std::min(__n, __unsampled_sz); __n != 0; ++__first)
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if (__d(__g, __param_type{0, --__unsampled_sz}) < __n)
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{
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*__out++ = *__first;
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--__n;
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}
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return __out;
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}
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/// Take a random sample from a population.
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template<typename _PopulationIterator, typename _SampleIterator,
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typename _Distance, typename _UniformRandomNumberGenerator>
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_SampleIterator
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sample(_PopulationIterator __first, _PopulationIterator __last,
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_SampleIterator __out, _Distance __n,
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_UniformRandomNumberGenerator&& __g)
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{
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using __pop_cat = typename
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std::iterator_traits<_PopulationIterator>::iterator_category;
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using __samp_cat = typename
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std::iterator_traits<_SampleIterator>::iterator_category;
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static_assert(
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__or_<is_convertible<__pop_cat, forward_iterator_tag>,
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is_convertible<__samp_cat, random_access_iterator_tag>>::value,
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"output range must use a RandomAccessIterator when input range"
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" does not meet the ForwardIterator requirements");
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static_assert(is_integral<_Distance>::value,
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"sample size must be an integer type");
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return std::experimental::__sample(
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__first, __last, __pop_cat{}, __out, __samp_cat{},
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__n, std::forward<_UniformRandomNumberGenerator>(__g));
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace fundamentals_v1
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} // namespace experimental
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} // namespace std
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#endif // C++14
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#endif // _GLIBCXX_EXPERIMENTAL_ALGORITHM
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