| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___ALGORITHM_SAMPLE_H |
| #define _LIBCPP___ALGORITHM_SAMPLE_H |
| |
| #include <__algorithm/iterator_operations.h> |
| #include <__algorithm/min.h> |
| #include <__assert> |
| #include <__config> |
| #include <__iterator/distance.h> |
| #include <__iterator/iterator_traits.h> |
| #include <__random/uniform_int_distribution.h> |
| #include <__type_traits/common_type.h> |
| #include <__utility/move.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| _LIBCPP_PUSH_MACROS |
| #include <__undef_macros> |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| template <class _AlgPolicy, |
| class _PopulationIterator, class _PopulationSentinel, class _SampleIterator, class _Distance, |
| class _UniformRandomNumberGenerator> |
| _LIBCPP_INLINE_VISIBILITY |
| _SampleIterator __sample(_PopulationIterator __first, |
| _PopulationSentinel __last, _SampleIterator __output_iter, |
| _Distance __n, |
| _UniformRandomNumberGenerator& __g, |
| input_iterator_tag) { |
| |
| _Distance __k = 0; |
| for (; __first != __last && __k < __n; ++__first, (void) ++__k) |
| __output_iter[__k] = *__first; |
| _Distance __sz = __k; |
| for (; __first != __last; ++__first, (void) ++__k) { |
| _Distance __r = uniform_int_distribution<_Distance>(0, __k)(__g); |
| if (__r < __sz) |
| __output_iter[__r] = *__first; |
| } |
| return __output_iter + _VSTD::min(__n, __k); |
| } |
| |
| template <class _AlgPolicy, |
| class _PopulationIterator, class _PopulationSentinel, class _SampleIterator, class _Distance, |
| class _UniformRandomNumberGenerator> |
| _LIBCPP_INLINE_VISIBILITY |
| _SampleIterator __sample(_PopulationIterator __first, |
| _PopulationSentinel __last, _SampleIterator __output_iter, |
| _Distance __n, |
| _UniformRandomNumberGenerator& __g, |
| forward_iterator_tag) { |
| _Distance __unsampled_sz = _IterOps<_AlgPolicy>::distance(__first, __last); |
| for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) { |
| _Distance __r = uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g); |
| if (__r < __n) { |
| *__output_iter++ = *__first; |
| --__n; |
| } |
| } |
| return __output_iter; |
| } |
| |
| template <class _AlgPolicy, |
| class _PopulationIterator, class _PopulationSentinel, class _SampleIterator, class _Distance, |
| class _UniformRandomNumberGenerator> |
| _LIBCPP_INLINE_VISIBILITY |
| _SampleIterator __sample(_PopulationIterator __first, |
| _PopulationSentinel __last, _SampleIterator __output_iter, |
| _Distance __n, _UniformRandomNumberGenerator& __g) { |
| _LIBCPP_ASSERT_UNCATEGORIZED(__n >= 0, "N must be a positive number."); |
| |
| using _PopIterCategory = typename _IterOps<_AlgPolicy>::template __iterator_category<_PopulationIterator>; |
| using _Difference = typename _IterOps<_AlgPolicy>::template __difference_type<_PopulationIterator>; |
| using _CommonType = typename common_type<_Distance, _Difference>::type; |
| |
| return std::__sample<_AlgPolicy>( |
| std::move(__first), std::move(__last), std::move(__output_iter), _CommonType(__n), |
| __g, _PopIterCategory()); |
| } |
| |
| #if _LIBCPP_STD_VER >= 17 |
| template <class _PopulationIterator, class _SampleIterator, class _Distance, |
| class _UniformRandomNumberGenerator> |
| inline _LIBCPP_INLINE_VISIBILITY |
| _SampleIterator sample(_PopulationIterator __first, |
| _PopulationIterator __last, _SampleIterator __output_iter, |
| _Distance __n, _UniformRandomNumberGenerator&& __g) { |
| static_assert(__has_forward_iterator_category<_PopulationIterator>::value || |
| __has_random_access_iterator_category<_SampleIterator>::value, |
| "SampleIterator must meet the requirements of RandomAccessIterator"); |
| |
| return std::__sample<_ClassicAlgPolicy>( |
| std::move(__first), std::move(__last), std::move(__output_iter), __n, __g); |
| } |
| |
| #endif // _LIBCPP_STD_VER >= 17 |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| _LIBCPP_POP_MACROS |
| |
| #endif // _LIBCPP___ALGORITHM_SAMPLE_H |