is_heap.h

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/***************************************************************************
 * include/stxxl/bits/common/is_heap.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2015 Timo Bingmann <[email protected]>
 *
 * 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)
 **************************************************************************/

#ifndef STXXL_COMMON_IS_HEAP_HEADER
#define STXXL_COMMON_IS_HEAP_HEADER

#include <stxxl/bits/namespace.h>
#include <iterator>
#include <functional>

STXXL_BEGIN_NAMESPACE

template <typename RandomAccessIterator, typename StrictWeakOrdering>
bool is_heap(
 RandomAccessIterator first, RandomAccessIterator last,
 StrictWeakOrdering comp =
 std::less<typename std::iterator_traits<RandomAccessIterator>
 ::value_type>())
{
 typedef typename std::iterator_traits<RandomAccessIterator>
 ::difference_type diff_type;

 if (first == last) return true;

 RandomAccessIterator parent = first;

 diff_type num = 1;
 for (RandomAccessIterator child = first + 1; child != last; ++child, ++num)
 {
 if (comp(*parent, *child)) // parent < child -> max-heap violated
 return false;

 if ((num & 1) == 0)
 ++parent;
 }

 return true;
}

STXXL_END_NAMESPACE

#endif // !STXXL_COMMON_IS_HEAP_HEADER