5aaefa510e
libc++ has started splicing standard library headers into much more fine-grained content for maintainability. It's very likely that outdated and naive tooling (some of which is outside of LLVM's scope) will suggest users include things such as <__ranges/access.h> instead of <ranges>, and Hyrum's law suggests that users will eventually begin to rely on this without the help of tooling. As such, this commit intends to protect users from themselves, by making it a hard error for anyone outside of the standard library to include libc++ detail headers. Differential Revision: https://reviews.llvm.org/D106124
104 lines
3.9 KiB
C++
104 lines
3.9 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ALGORITHM_SAMPLE_H
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#define _LIBCPP___ALGORITHM_SAMPLE_H
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#include <__algorithm/min.h>
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#include <__assert>
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#include <__config>
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#include <__random/uniform_int_distribution.h>
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#include <iterator>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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# pragma clang include_instead(<algorithm>)
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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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 __output_iter,
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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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__output_iter[__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 = uniform_int_distribution<_Distance>(0, __k)(__g);
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if (__r < __sz)
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__output_iter[__r] = *__first;
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}
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return __output_iter + _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 __output_iter,
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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 = uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
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if (__r < __n) {
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*__output_iter++ = *__first;
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--__n;
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}
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}
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return __output_iter;
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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 __output_iter,
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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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static_assert(__is_cpp17_forward_iterator<_PopulationIterator>::value ||
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__is_cpp17_random_access_iterator<_SampleIterator>::value,
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"SampleIterator must meet the requirements of RandomAccessIterator");
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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::__sample(
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__first, __last, __output_iter, _CommonType(__n),
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__g, _PopCategory());
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}
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#if _LIBCPP_STD_VER > 14
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template <class _PopulationIterator, class _SampleIterator, class _Distance,
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class _UniformRandomNumberGenerator>
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inline _LIBCPP_INLINE_VISIBILITY
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_SampleIterator sample(_PopulationIterator __first,
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_PopulationIterator __last, _SampleIterator __output_iter,
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_Distance __n, _UniformRandomNumberGenerator&& __g) {
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return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
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}
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#endif // _LIBCPP_STD_VER > 14
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ALGORITHM_SAMPLE_H
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