1 // <experimental/algorithm> -*- C++ -*-
3 // Copyright (C) 2014-2016 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
25 /** @file experimental/algorithm
26 * This is a TS C++ Library header.
29 #ifndef _GLIBCXX_EXPERIMENTAL_ALGORITHM
30 #define _GLIBCXX_EXPERIMENTAL_ALGORITHM 1
32 #pragma GCC system_header
34 #if __cplusplus <= 201103L
35 # include <bits/c++14_warning.h>
40 #include <experimental/bits/lfts_config.h>
42 namespace std _GLIBCXX_VISIBILITY(default)
44 namespace experimental
46 inline namespace fundamentals_v1
48 _GLIBCXX_BEGIN_NAMESPACE_VERSION
50 template<typename _ForwardIterator, typename _Searcher>
51 inline _ForwardIterator
52 search(_ForwardIterator __first, _ForwardIterator __last,
53 const _Searcher& __searcher)
54 { return __searcher(__first, __last); }
56 #define __cpp_lib_experimental_sample 201402
58 /// Reservoir sampling algorithm.
59 template<typename _InputIterator, typename _RandomAccessIterator,
60 typename _Size, typename _UniformRandomNumberGenerator>
62 __sample(_InputIterator __first, _InputIterator __last, input_iterator_tag,
63 _RandomAccessIterator __out, random_access_iterator_tag,
64 _Size __n, _UniformRandomNumberGenerator&& __g)
66 using __distrib_type = std::uniform_int_distribution<_Size>;
67 using __param_type = typename __distrib_type::param_type;
69 _Size __sample_sz = 0;
70 while (__first != __last && __sample_sz != __n)
71 __out[__sample_sz++] = *__first++;
72 for (auto __pop_sz = __sample_sz; __first != __last;
73 ++__first, ++__pop_sz)
75 const auto __k = __d(__g, __param_type{0, __pop_sz});
77 __out[__k] = *__first;
79 return __out + __sample_sz;
82 /// Selection sampling algorithm.
83 template<typename _ForwardIterator, typename _OutputIterator, typename _Cat,
84 typename _Size, typename _UniformRandomNumberGenerator>
86 __sample(_ForwardIterator __first, _ForwardIterator __last,
88 _OutputIterator __out, _Cat,
89 _Size __n, _UniformRandomNumberGenerator&& __g)
91 using __distrib_type = std::uniform_int_distribution<_Size>;
92 using __param_type = typename __distrib_type::param_type;
94 _Size __unsampled_sz = std::distance(__first, __last);
95 for (__n = std::min(__n, __unsampled_sz); __n != 0; ++__first)
96 if (__d(__g, __param_type{0, --__unsampled_sz}) < __n)
104 /// Take a random sample from a population.
105 template<typename _PopulationIterator, typename _SampleIterator,
106 typename _Distance, typename _UniformRandomNumberGenerator>
108 sample(_PopulationIterator __first, _PopulationIterator __last,
109 _SampleIterator __out, _Distance __n,
110 _UniformRandomNumberGenerator&& __g)
112 using __pop_cat = typename
113 std::iterator_traits<_PopulationIterator>::iterator_category;
114 using __samp_cat = typename
115 std::iterator_traits<_SampleIterator>::iterator_category;
118 __or_<is_convertible<__pop_cat, forward_iterator_tag>,
119 is_convertible<__samp_cat, random_access_iterator_tag>>::value,
120 "output range must use a RandomAccessIterator when input range"
121 " does not meet the ForwardIterator requirements");
123 static_assert(is_integral<_Distance>::value,
124 "sample size must be an integer type");
126 return std::experimental::__sample(
127 __first, __last, __pop_cat{}, __out, __samp_cat{},
128 __n, std::forward<_UniformRandomNumberGenerator>(__g));
131 _GLIBCXX_END_NAMESPACE_VERSION
132 } // namespace fundamentals_v1
133 } // namespace experimental
138 #endif // _GLIBCXX_EXPERIMENTAL_ALGORITHM