experimental/algorithm
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// <experimental/algorithm> -*- C++ -*-
// Copyright (C) 2014-2016 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file experimental/algorithm
* This is a TS C++ Library header.
*/
#ifndef _GLIBCXX_EXPERIMENTAL_ALGORITHM
#define _GLIBCXX_EXPERIMENTAL_ALGORITHM 1
#pragma GCC system_header
#if __cplusplus <= 201103L
# include <bits/c++14_warning.h>
#else
#include <algorithm>
#include <random>
#include <experimental/bits/lfts_config.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
namespace experimental
{
inline namespace fundamentals_v1
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _ForwardIterator, typename _Searcher>
inline _ForwardIterator
search(_ForwardIterator __first, _ForwardIterator __last,
const _Searcher& __searcher)
{ return __searcher(__first, __last); }
#define __cpp_lib_experimental_sample 201402
/// Reservoir sampling algorithm.
template<typename _InputIterator, typename _RandomAccessIterator,
typename _Size, typename _UniformRandomNumberGenerator>
_RandomAccessIterator
__sample(_InputIterator __first, _InputIterator __last, input_iterator_tag,
_RandomAccessIterator __out, random_access_iterator_tag,
_Size __n, _UniformRandomNumberGenerator&& __g)
{
using __distrib_type = std::uniform_int_distribution<_Size>;
using __param_type = typename __distrib_type::param_type;
__distrib_type __d{};
_Size __sample_sz = 0;
while (__first != __last && __sample_sz != __n)
{
__out[__sample_sz++] = *__first;
++__first;
}
for (auto __pop_sz = __sample_sz; __first != __last;
++__first, (void)++__pop_sz)
{
const auto __k = __d(__g, __param_type{0, __pop_sz});
if (__k < __n)
__out[__k] = *__first;
}
return __out + __sample_sz;
}
/// Selection sampling algorithm.
template<typename _ForwardIterator, typename _OutputIterator, typename _Cat,
typename _Size, typename _UniformRandomNumberGenerator>
_OutputIterator
__sample(_ForwardIterator __first, _ForwardIterator __last,
forward_iterator_tag,
_OutputIterator __out, _Cat,
_Size __n, _UniformRandomNumberGenerator&& __g)
{
using __distrib_type = std::uniform_int_distribution<_Size>;
using __param_type = typename __distrib_type::param_type;
__distrib_type __d{};
_Size __unsampled_sz = std::distance(__first, __last);
for (__n = std::min(__n, __unsampled_sz); __n != 0; ++__first)
if (__d(__g, __param_type{0, --__unsampled_sz}) < __n)
{
*__out++ = *__first;
--__n;
}
return __out;
}
/// Take a random sample from a population.
template<typename _PopulationIterator, typename _SampleIterator,
typename _Distance, typename _UniformRandomNumberGenerator>
_SampleIterator
sample(_PopulationIterator __first, _PopulationIterator __last,
_SampleIterator __out, _Distance __n,
_UniformRandomNumberGenerator&& __g)
{
using __pop_cat = typename
std::iterator_traits<_PopulationIterator>::iterator_category;
using __samp_cat = typename
std::iterator_traits<_SampleIterator>::iterator_category;
static_assert(
__or_<is_convertible<__pop_cat, forward_iterator_tag>,
is_convertible<__samp_cat, random_access_iterator_tag>>::value,
"output range must use a RandomAccessIterator when input range"
" does not meet the ForwardIterator requirements");
static_assert(is_integral<_Distance>::value,
"sample size must be an integer type");
typename iterator_traits<_PopulationIterator>::difference_type __d = __n;
return std::experimental::__sample(
__first, __last, __pop_cat{}, __out, __samp_cat{},
__d, std::forward<_UniformRandomNumberGenerator>(__g));
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace fundamentals_v1
} // namespace experimental
} // namespace std
#endif // C++14
#endif // _GLIBCXX_EXPERIMENTAL_ALGORITHM