libcxx/include/__algorithm/pop_heap.h

   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
  35 void __pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp,
  36     typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
  37   _LIBCPP_ASSERT_UNCATEGORIZED(__len > 0, "The heap given to pop_heap must be non-empty");
  38
  39   __comp_ref_type<_Compare> __comp_ref = __comp;
  40
  41   using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
  42   if (__len > 1) {
  43     value_type __top = _IterOps<_AlgPolicy>::__iter_move(__first);  // create a hole at __first
  44     _RandomAccessIterator __hole = std::__floyd_sift_down<_AlgPolicy>(__first, __comp_ref, __len);
  45     --__last;
  46
  47     if (__hole == __last) {
  48       *__hole = std::move(__top);
  49     } else {
  50       *__hole = _IterOps<_AlgPolicy>::__iter_move(__last);
  51       ++__hole;
  52       *__last = std::move(__top);
  53       std::__sift_up<_AlgPolicy>(__first, __hole, __comp_ref, __hole - __first);
  54     }
  55   }
  56 }
  57
  58 template <class _RandomAccessIterator, class _Compare>
  59 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  60 void pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
  61   static_assert(std::is_copy_constructible<_RandomAccessIterator>::value, "Iterators must be copy constructible.");
  62   static_assert(std::is_copy_assignable<_RandomAccessIterator>::value, "Iterators must be copy assignable.");
  63
  64   typename iterator_traits<_RandomAccessIterator>::difference_type __len = __last - __first;
  65   std::__pop_heap<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, __len);
  66 }
  67
  68 template <class _RandomAccessIterator>
  69 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  70 void pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) {
  71   std::pop_heap(std::move(__first), std::move(__last), __less<>());
  72 }
  73
  74 _LIBCPP_END_NAMESPACE_STD
  75
  76 _LIBCPP_POP_MACROS
  77
  78 #endif // _LIBCPP___ALGORITHM_POP_HEAP_H