LCOM1920-T02G10

// -*- C++ -*-

//===-------------------------- algorithm ---------------------------------===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is dual licensed under the MIT and the University of Illinois Open

// Source Licenses. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_EXPERIMENTAL_ALGORITHM

#define _LIBCPP_EXPERIMENTAL_ALGORITHM

/*

   experimental/algorithm synopsis

#include <algorithm>

namespace std {

namespace experimental {

inline namespace fundamentals_v1 {

template <class ForwardIterator, class Searcher>

ForwardIterator search(ForwardIterator first, ForwardIterator last,

                       const Searcher &searcher);

template <class PopulationIterator, class SampleIterator, class Distance,

          class UniformRandomNumberGenerator>

SampleIterator sample(PopulationIterator first, PopulationIterator last,

                      SampleIterator out, Distance n,

                      UniformRandomNumberGenerator &&g);

} // namespace fundamentals_v1

} // namespace experimental

} // namespace std

*/

#include <experimental/__config>

#include <algorithm>

#include <type_traits>

#include <__undef_min_max>

#include <__debug>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

#pragma GCC system_header

#endif

_LIBCPP_BEGIN_NAMESPACE_LFTS

template <class _ForwardIterator, class _Searcher>

_LIBCPP_INLINE_VISIBILITY

_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)

{ return __s(__f, __l); }

template <class _PopulationIterator, class _SampleIterator, class _Distance,

          class _UniformRandomNumberGenerator>

_LIBCPP_INLINE_VISIBILITY

_SampleIterator __sample(_PopulationIterator __first,

                         _PopulationIterator __last, _SampleIterator __out,

                         _Distance __n,

                         _UniformRandomNumberGenerator &&__g,

                         input_iterator_tag) {

  _Distance __k = 0;

  for (; __first != __last && __k < __n; ++__first, (void)++__k)

    __out[__k] = *__first;

  _Distance __sz = __k;

  for (; __first != __last; ++__first, (void)++__k) {

    _Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);

    if (__r < __sz)

      __out[__r] = *__first;

  }

  return __out + _VSTD::min(__n, __k);

}

template <class _PopulationIterator, class _SampleIterator, class _Distance,

          class _UniformRandomNumberGenerator>

_LIBCPP_INLINE_VISIBILITY

_SampleIterator __sample(_PopulationIterator __first,

                         _PopulationIterator __last, _SampleIterator __out,

                         _Distance __n,

                         _UniformRandomNumberGenerator &&__g,

                         forward_iterator_tag) {

  _Distance __unsampled_sz = _VSTD::distance(__first, __last);

  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {

    _Distance __r =

        _VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);

    if (__r < __n) {

      *__out++ = *__first;

      --__n;

    }

  }

  return __out;

}

template <class _PopulationIterator, class _SampleIterator, class _Distance,

          class _UniformRandomNumberGenerator>

_LIBCPP_INLINE_VISIBILITY

_SampleIterator sample(_PopulationIterator __first,

                         _PopulationIterator __last, _SampleIterator __out,

                         _Distance __n, _UniformRandomNumberGenerator &&__g) {

  typedef typename iterator_traits<_PopulationIterator>::iterator_category

        _PopCategory;

  typedef typename iterator_traits<_PopulationIterator>::difference_type

        _Difference;

  typedef typename common_type<_Distance, _Difference>::type _CommonType;

  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");

  return _VSTD_LFTS::__sample(

      __first, __last, __out, _CommonType(__n),

      _VSTD::forward<_UniformRandomNumberGenerator>(__g),

      _PopCategory());

}

_LIBCPP_END_NAMESPACE_LFTS

#endif /* _LIBCPP_EXPERIMENTAL_ALGORITHM */