boost/move/algo/detail/heap_sort.hpp
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2017-2018.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/move for documentation.
//
//////////////////////////////////////////////////////////////////////////////
//! \file
#ifndef BOOST_MOVE_DETAIL_HEAP_SORT_HPP
#define BOOST_MOVE_DETAIL_HEAP_SORT_HPP
#ifndef BOOST_CONFIG_HPP
# include <boost/config.hpp>
#endif
#
#if defined(BOOST_HAS_PRAGMA_ONCE)
# pragma once
#endif
#include <boost/move/detail/config_begin.hpp>
#include <boost/move/detail/workaround.hpp>
#include <boost/move/detail/iterator_traits.hpp>
#include <boost/move/algo/detail/is_sorted.hpp>
#include <boost/move/utility_core.hpp>
#if defined(BOOST_CLANG) || (defined(BOOST_GCC) && (BOOST_GCC >= 40600))
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-conversion"
#endif
namespace boost { namespace movelib{
template <class RandomAccessIterator, class Compare>
class heap_sort_helper
{
typedef typename boost::movelib::iterator_traits<RandomAccessIterator>::size_type size_type;
typedef typename boost::movelib::iterator_traits<RandomAccessIterator>::value_type value_type;
static void adjust_heap(RandomAccessIterator first, size_type hole_index, size_type const len, value_type &value, Compare comp)
{
size_type const top_index = hole_index;
size_type second_child = size_type(2u*(hole_index + 1u));
while (second_child < len) {
if (comp(*(first + second_child), *(first + size_type(second_child - 1u))))
second_child--;
*(first + hole_index) = boost::move(*(first + second_child));
hole_index = second_child;
second_child = size_type(2u * (second_child + 1u));
}
if (second_child == len) {
*(first + hole_index) = boost::move(*(first + size_type(second_child - 1u)));
hole_index = size_type(second_child - 1);
}
{ //push_heap-like ending
size_type parent = size_type((hole_index - 1u) / 2u);
while (hole_index > top_index && comp(*(first + parent), value)) {
*(first + hole_index) = boost::move(*(first + parent));
hole_index = parent;
parent = size_type((hole_index - 1u) / 2u);
}
*(first + hole_index) = boost::move(value);
}
}
static void make_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
size_type const len = size_type(last - first);
if (len > 1) {
size_type parent = size_type(len/2u - 1u);
do {
value_type v(boost::move(*(first + parent)));
adjust_heap(first, parent, len, v, comp);
}while (parent--);
}
}
static void sort_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
size_type len = size_type(last - first);
while (len > 1) {
//move biggest to the safe zone
--last;
value_type v(boost::move(*last));
*last = boost::move(*first);
adjust_heap(first, size_type(0), --len, v, comp);
}
}
public:
static void sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
make_heap(first, last, comp);
sort_heap(first, last, comp);
BOOST_ASSERT(boost::movelib::is_sorted(first, last, comp));
}
};
template <class RandomAccessIterator, class Compare>
BOOST_MOVE_FORCEINLINE void heap_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp)
{
heap_sort_helper<RandomAccessIterator, Compare>::sort(first, last, comp);
}
}} //namespace boost { namespace movelib{
#if defined(BOOST_CLANG) || (defined(BOOST_GCC) && (BOOST_GCC >= 40600))
#pragma GCC diagnostic pop
#endif
#include <boost/move/detail/config_end.hpp>
#endif //#ifndef BOOST_MOVE_DETAIL_HEAP_SORT_HPP