libstdc++
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00001 // <experimental/algorithm> -*- C++ -*- 00002 00003 // Copyright (C) 2014-2016 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file experimental/algorithm 00026 * This is a TS C++ Library header. 00027 */ 00028 00029 #ifndef _GLIBCXX_EXPERIMENTAL_ALGORITHM 00030 #define _GLIBCXX_EXPERIMENTAL_ALGORITHM 1 00031 00032 #pragma GCC system_header 00033 00034 #if __cplusplus <= 201103L 00035 # include <bits/c++14_warning.h> 00036 #else 00037 00038 #include <algorithm> 00039 #include <random> 00040 #include <experimental/bits/lfts_config.h> 00041 00042 namespace std _GLIBCXX_VISIBILITY(default) 00043 { 00044 namespace experimental 00045 { 00046 inline namespace fundamentals_v1 00047 { 00048 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00049 00050 template<typename _ForwardIterator, typename _Searcher> 00051 inline _ForwardIterator 00052 search(_ForwardIterator __first, _ForwardIterator __last, 00053 const _Searcher& __searcher) 00054 { return __searcher(__first, __last); } 00055 00056 #define __cpp_lib_experimental_sample 201402 00057 00058 /// Reservoir sampling algorithm. 00059 template<typename _InputIterator, typename _RandomAccessIterator, 00060 typename _Size, typename _UniformRandomNumberGenerator> 00061 _RandomAccessIterator 00062 __sample(_InputIterator __first, _InputIterator __last, input_iterator_tag, 00063 _RandomAccessIterator __out, random_access_iterator_tag, 00064 _Size __n, _UniformRandomNumberGenerator&& __g) 00065 { 00066 using __distrib_type = std::uniform_int_distribution<_Size>; 00067 using __param_type = typename __distrib_type::param_type; 00068 __distrib_type __d{}; 00069 _Size __sample_sz = 0; 00070 while (__first != __last && __sample_sz != __n) 00071 { 00072 __out[__sample_sz++] = *__first; 00073 ++__first; 00074 } 00075 for (auto __pop_sz = __sample_sz; __first != __last; 00076 ++__first, (void)++__pop_sz) 00077 { 00078 const auto __k = __d(__g, __param_type{0, __pop_sz}); 00079 if (__k < __n) 00080 __out[__k] = *__first; 00081 } 00082 return __out + __sample_sz; 00083 } 00084 00085 /// Selection sampling algorithm. 00086 template<typename _ForwardIterator, typename _OutputIterator, typename _Cat, 00087 typename _Size, typename _UniformRandomNumberGenerator> 00088 _OutputIterator 00089 __sample(_ForwardIterator __first, _ForwardIterator __last, 00090 forward_iterator_tag, 00091 _OutputIterator __out, _Cat, 00092 _Size __n, _UniformRandomNumberGenerator&& __g) 00093 { 00094 using __distrib_type = std::uniform_int_distribution<_Size>; 00095 using __param_type = typename __distrib_type::param_type; 00096 __distrib_type __d{}; 00097 _Size __unsampled_sz = std::distance(__first, __last); 00098 for (__n = std::min(__n, __unsampled_sz); __n != 0; ++__first) 00099 if (__d(__g, __param_type{0, --__unsampled_sz}) < __n) 00100 { 00101 *__out++ = *__first; 00102 --__n; 00103 } 00104 return __out; 00105 } 00106 00107 /// Take a random sample from a population. 00108 template<typename _PopulationIterator, typename _SampleIterator, 00109 typename _Distance, typename _UniformRandomNumberGenerator> 00110 _SampleIterator 00111 sample(_PopulationIterator __first, _PopulationIterator __last, 00112 _SampleIterator __out, _Distance __n, 00113 _UniformRandomNumberGenerator&& __g) 00114 { 00115 using __pop_cat = typename 00116 std::iterator_traits<_PopulationIterator>::iterator_category; 00117 using __samp_cat = typename 00118 std::iterator_traits<_SampleIterator>::iterator_category; 00119 00120 static_assert( 00121 __or_<is_convertible<__pop_cat, forward_iterator_tag>, 00122 is_convertible<__samp_cat, random_access_iterator_tag>>::value, 00123 "output range must use a RandomAccessIterator when input range" 00124 " does not meet the ForwardIterator requirements"); 00125 00126 static_assert(is_integral<_Distance>::value, 00127 "sample size must be an integer type"); 00128 00129 typename iterator_traits<_PopulationIterator>::difference_type __d = __n; 00130 return std::experimental::__sample( 00131 __first, __last, __pop_cat{}, __out, __samp_cat{}, 00132 __d, std::forward<_UniformRandomNumberGenerator>(__g)); 00133 } 00134 00135 _GLIBCXX_END_NAMESPACE_VERSION 00136 } // namespace fundamentals_v1 00137 } // namespace experimental 00138 } // namespace std 00139 00140 #endif // C++14 00141 00142 #endif // _GLIBCXX_EXPERIMENTAL_ALGORITHM