e78f53d1e8
This reverts commit 68c04b0ae62d8431d72d8b47fc13008002ee4387. This disables the IWYU mapping that caused the failure, since the headers aren't reachable for now. This is the first part of the "Freezing C++03 headers" proposal explained in https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319/58. This patch mechanically copies the headers as of the LLVM 19.1 release into a subdirectory of libc++ so that we can start using these headers when building in C++03 mode. We are going to be backporting important changes to that copy of the headers until the LLVM 21 release. After the LLVM 21 release, only critical bugfixes will be fixed in the C++03 copy of the headers. This patch only performs a copy of the headers -- these headers are still unused by the rest of the codebase.
119 lines
3.8 KiB
C++
119 lines
3.8 KiB
C++
//===----------------------------------------------------------------------===//
|
|
//
|
|
// 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_SIFT_DOWN_H
|
|
#define _LIBCPP___ALGORITHM_SIFT_DOWN_H
|
|
|
|
#include <__algorithm/iterator_operations.h>
|
|
#include <__assert>
|
|
#include <__config>
|
|
#include <__iterator/iterator_traits.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 _Compare, class _RandomAccessIterator>
|
|
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
|
|
__sift_down(_RandomAccessIterator __first,
|
|
_Compare&& __comp,
|
|
typename iterator_traits<_RandomAccessIterator>::difference_type __len,
|
|
_RandomAccessIterator __start) {
|
|
using _Ops = _IterOps<_AlgPolicy>;
|
|
|
|
typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
|
|
typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
|
|
// left-child of __start is at 2 * __start + 1
|
|
// right-child of __start is at 2 * __start + 2
|
|
difference_type __child = __start - __first;
|
|
|
|
if (__len < 2 || (__len - 2) / 2 < __child)
|
|
return;
|
|
|
|
__child = 2 * __child + 1;
|
|
_RandomAccessIterator __child_i = __first + __child;
|
|
|
|
if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + difference_type(1)))) {
|
|
// right-child exists and is greater than left-child
|
|
++__child_i;
|
|
++__child;
|
|
}
|
|
|
|
// check if we are in heap-order
|
|
if (__comp(*__child_i, *__start))
|
|
// we are, __start is larger than its largest child
|
|
return;
|
|
|
|
value_type __top(_Ops::__iter_move(__start));
|
|
do {
|
|
// we are not in heap-order, swap the parent with its largest child
|
|
*__start = _Ops::__iter_move(__child_i);
|
|
__start = __child_i;
|
|
|
|
if ((__len - 2) / 2 < __child)
|
|
break;
|
|
|
|
// recompute the child based off of the updated parent
|
|
__child = 2 * __child + 1;
|
|
__child_i = __first + __child;
|
|
|
|
if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + difference_type(1)))) {
|
|
// right-child exists and is greater than left-child
|
|
++__child_i;
|
|
++__child;
|
|
}
|
|
|
|
// check if we are in heap-order
|
|
} while (!__comp(*__child_i, __top));
|
|
*__start = std::move(__top);
|
|
}
|
|
|
|
template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
|
|
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _RandomAccessIterator __floyd_sift_down(
|
|
_RandomAccessIterator __first,
|
|
_Compare&& __comp,
|
|
typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
|
|
using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
|
|
_LIBCPP_ASSERT_INTERNAL(__len >= 2, "shouldn't be called unless __len >= 2");
|
|
|
|
_RandomAccessIterator __hole = __first;
|
|
_RandomAccessIterator __child_i = __first;
|
|
difference_type __child = 0;
|
|
|
|
while (true) {
|
|
__child_i += difference_type(__child + 1);
|
|
__child = 2 * __child + 1;
|
|
|
|
if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + difference_type(1)))) {
|
|
// right-child exists and is greater than left-child
|
|
++__child_i;
|
|
++__child;
|
|
}
|
|
|
|
// swap __hole with its largest child
|
|
*__hole = _IterOps<_AlgPolicy>::__iter_move(__child_i);
|
|
__hole = __child_i;
|
|
|
|
// if __hole is now a leaf, we're done
|
|
if (__child > (__len - 2) / 2)
|
|
return __hole;
|
|
}
|
|
}
|
|
|
|
_LIBCPP_END_NAMESPACE_STD
|
|
|
|
_LIBCPP_POP_MACROS
|
|
|
|
#endif // _LIBCPP___ALGORITHM_SIFT_DOWN_H
|