llvm-project/libcxx/include/experimental/algorithm

121 lines
4.0 KiB
C++

// -*- 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).first; }
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 */