1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___ALGORITHM_POP_HEAP_H 10 #define _LIBCPP___ALGORITHM_POP_HEAP_H 11 12 #include <__algorithm/comp.h> 13 #include <__algorithm/comp_ref_type.h> 14 #include <__algorithm/iterator_operations.h> 15 #include <__algorithm/push_heap.h> 16 #include <__algorithm/sift_down.h> 17 #include <__assert> 18 #include <__config> 19 #include <__iterator/iterator_traits.h> 20 #include <__type_traits/is_copy_assignable.h> 21 #include <__type_traits/is_copy_constructible.h> 22 #include <__utility/move.h> 23 24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 25 # pragma GCC system_header 26 #endif 27 28 _LIBCPP_PUSH_MACROS 29 #include <__undef_macros> 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 33 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator> 34 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void 35 __pop_heap(_RandomAccessIterator __first, 36 _RandomAccessIterator __last, 37 _Compare& __comp, 38 typename iterator_traits<_RandomAccessIterator>::difference_type __len) { 39 // Calling `pop_heap` on an empty range is undefined behavior, but in practice it will be a no-op. 40 _LIBCPP_ASSERT_PEDANTIC(__len > 0, "The heap given to pop_heap must be non-empty"); 41 42 __comp_ref_type<_Compare> __comp_ref = __comp; 43 44 using value_type = typename iterator_traits<_RandomAccessIterator>::value_type; 45 if (__len > 1) { 46 value_type __top = _IterOps<_AlgPolicy>::__iter_move(__first); // create a hole at __first 47 _RandomAccessIterator __hole = std::__floyd_sift_down<_AlgPolicy>(__first, __comp_ref, __len); 48 --__last; 49 50 if (__hole == __last) { 51 *__hole = std::move(__top); 52 } else { 53 *__hole = _IterOps<_AlgPolicy>::__iter_move(__last); 54 ++__hole; 55 *__last = std::move(__top); 56 std::__sift_up<_AlgPolicy>(__first, __hole, __comp_ref, __hole - __first); 57 } 58 } 59 } 60 61 template <class _RandomAccessIterator, class _Compare> 62 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void 63 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) { 64 static_assert(std::is_copy_constructible<_RandomAccessIterator>::value, "Iterators must be copy constructible."); 65 static_assert(std::is_copy_assignable<_RandomAccessIterator>::value, "Iterators must be copy assignable."); 66 67 typename iterator_traits<_RandomAccessIterator>::difference_type __len = __last - __first; 68 std::__pop_heap<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, __len); 69 } 70 71 template <class _RandomAccessIterator> 72 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void 73 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) { 74 std::pop_heap(std::move(__first), std::move(__last), __less<>()); 75 } 76 77 _LIBCPP_END_NAMESPACE_STD 78 79 _LIBCPP_POP_MACROS 80 81 #endif // _LIBCPP___ALGORITHM_POP_HEAP_H 82