forked from OSchip/llvm-project
121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
// -*- C++ -*-
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//===-------------------------- algorithm ---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP_EXPERIMENTAL_ALGORITHM
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#define _LIBCPP_EXPERIMENTAL_ALGORITHM
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/*
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experimental/algorithm synopsis
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#include <algorithm>
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namespace std {
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namespace experimental {
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inline namespace fundamentals_v1 {
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template <class ForwardIterator, class Searcher>
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ForwardIterator search(ForwardIterator first, ForwardIterator last,
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const Searcher &searcher);
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template <class PopulationIterator, class SampleIterator, class Distance,
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class UniformRandomNumberGenerator>
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SampleIterator sample(PopulationIterator first, PopulationIterator last,
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SampleIterator out, Distance n,
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UniformRandomNumberGenerator &&g);
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} // namespace fundamentals_v1
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} // namespace experimental
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} // namespace std
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*/
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#include <experimental/__config>
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#include <algorithm>
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#include <type_traits>
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#include <__undef_min_max>
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#include <__debug>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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#pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_LFTS
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template <class _ForwardIterator, class _Searcher>
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_LIBCPP_INLINE_VISIBILITY
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_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
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{ return __s(__f, __l).first; }
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template <class _PopulationIterator, class _SampleIterator, class _Distance,
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class _UniformRandomNumberGenerator>
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_LIBCPP_INLINE_VISIBILITY
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_SampleIterator __sample(_PopulationIterator __first,
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_PopulationIterator __last, _SampleIterator __out,
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_Distance __n,
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_UniformRandomNumberGenerator &&__g,
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input_iterator_tag) {
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_Distance __k = 0;
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for (; __first != __last && __k < __n; ++__first, (void)++__k)
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__out[__k] = *__first;
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_Distance __sz = __k;
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for (; __first != __last; ++__first, (void)++__k) {
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_Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);
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if (__r < __sz)
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__out[__r] = *__first;
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}
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return __out + _VSTD::min(__n, __k);
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}
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template <class _PopulationIterator, class _SampleIterator, class _Distance,
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class _UniformRandomNumberGenerator>
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_LIBCPP_INLINE_VISIBILITY
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_SampleIterator __sample(_PopulationIterator __first,
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_PopulationIterator __last, _SampleIterator __out,
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_Distance __n,
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_UniformRandomNumberGenerator &&__g,
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forward_iterator_tag) {
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_Distance __unsampled_sz = _VSTD::distance(__first, __last);
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for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
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_Distance __r =
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_VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
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if (__r < __n) {
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*__out++ = *__first;
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--__n;
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}
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}
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return __out;
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}
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template <class _PopulationIterator, class _SampleIterator, class _Distance,
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class _UniformRandomNumberGenerator>
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_LIBCPP_INLINE_VISIBILITY
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_SampleIterator sample(_PopulationIterator __first,
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_PopulationIterator __last, _SampleIterator __out,
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_Distance __n, _UniformRandomNumberGenerator &&__g) {
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typedef typename iterator_traits<_PopulationIterator>::iterator_category
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_PopCategory;
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typedef typename iterator_traits<_PopulationIterator>::difference_type
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_Difference;
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typedef typename common_type<_Distance, _Difference>::type _CommonType;
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_LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
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return _VSTD_LFTS::__sample(
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__first, __last, __out, _CommonType(__n),
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_VSTD::forward<_UniformRandomNumberGenerator>(__g),
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_PopCategory());
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}
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_LIBCPP_END_NAMESPACE_LFTS
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#endif /* _LIBCPP_EXPERIMENTAL_ALGORITHM */
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