1// -*- C++ -*-
2//===-------------------------- algorithm ---------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_EXPERIMENTAL_ALGORITHM
12#define _LIBCPP_EXPERIMENTAL_ALGORITHM
13
14/*
15   experimental/algorithm synopsis
16
17#include <algorithm>
18
19namespace std {
20namespace experimental {
21inline namespace fundamentals_v1 {
22
23template <class ForwardIterator, class Searcher>
24ForwardIterator search(ForwardIterator first, ForwardIterator last,
25                       const Searcher &searcher);
26template <class PopulationIterator, class SampleIterator, class Distance,
27          class UniformRandomNumberGenerator>
28SampleIterator sample(PopulationIterator first, PopulationIterator last,
29                      SampleIterator out, Distance n,
30                      UniformRandomNumberGenerator &&g);
31
32} // namespace fundamentals_v1
33} // namespace experimental
34} // namespace std
35
36*/
37
38#include <experimental/__config>
39#include <algorithm>
40#include <type_traits>
41
42#include <__undef_min_max>
43
44#include <__debug>
45
46#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
47#pragma GCC system_header
48#endif
49
50_LIBCPP_BEGIN_NAMESPACE_LFTS
51
52
53template <class _ForwardIterator, class _Searcher>
54_LIBCPP_INLINE_VISIBILITY
55_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
56{ return __s(__f, __l); }
57
58
59template <class _PopulationIterator, class _SampleIterator, class _Distance,
60          class _UniformRandomNumberGenerator>
61_LIBCPP_INLINE_VISIBILITY
62_SampleIterator __sample(_PopulationIterator __first,
63                         _PopulationIterator __last, _SampleIterator __out,
64                         _Distance __n,
65                         _UniformRandomNumberGenerator &&__g,
66                         input_iterator_tag) {
67
68  _Distance __k = 0;
69  for (; __first != __last && __k < __n; ++__first, (void)++__k)
70    __out[__k] = *__first;
71  _Distance __sz = __k;
72  for (; __first != __last; ++__first, (void)++__k) {
73    _Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);
74    if (__r < __sz)
75      __out[__r] = *__first;
76  }
77  return __out + _VSTD::min(__n, __k);
78}
79
80template <class _PopulationIterator, class _SampleIterator, class _Distance,
81          class _UniformRandomNumberGenerator>
82_LIBCPP_INLINE_VISIBILITY
83_SampleIterator __sample(_PopulationIterator __first,
84                         _PopulationIterator __last, _SampleIterator __out,
85                         _Distance __n,
86                         _UniformRandomNumberGenerator &&__g,
87                         forward_iterator_tag) {
88  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
89  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
90    _Distance __r =
91        _VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
92    if (__r < __n) {
93      *__out++ = *__first;
94      --__n;
95    }
96  }
97  return __out;
98}
99
100template <class _PopulationIterator, class _SampleIterator, class _Distance,
101          class _UniformRandomNumberGenerator>
102_LIBCPP_INLINE_VISIBILITY
103_SampleIterator sample(_PopulationIterator __first,
104                         _PopulationIterator __last, _SampleIterator __out,
105                         _Distance __n, _UniformRandomNumberGenerator &&__g) {
106  typedef typename iterator_traits<_PopulationIterator>::iterator_category
107        _PopCategory;
108  typedef typename iterator_traits<_PopulationIterator>::difference_type
109        _Difference;
110  typedef typename common_type<_Distance, _Difference>::type _CommonType;
111  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
112  return _VSTD_LFTS::__sample(
113      __first, __last, __out, _CommonType(__n),
114      _VSTD::forward<_UniformRandomNumberGenerator>(__g),
115      _PopCategory());
116}
117
118_LIBCPP_END_NAMESPACE_LFTS
119
120#endif /* _LIBCPP_EXPERIMENTAL_ALGORITHM */
121