HEAP.H

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 */

#ifndef HEAP_H
#define HEAP_H

template <class RandomAccessIterator, class Distance, class T>
void __push_heap(RandomAccessIterator first, Distance holeIndex,
		 Distance topIndex, T value) {
    Distance parent = (holeIndex - 1) / 2;
    while (holeIndex > topIndex && *(first + parent) < value) {
	*(first + holeIndex) = *(first + parent);
	holeIndex = parent;
	parent = (holeIndex - 1) / 2;
    }    
    *(first + holeIndex) = value;
}

template <class RandomAccessIterator, class Distance, class T>
inline void __push_heap_aux(RandomAccessIterator first,
			    RandomAccessIterator last, Distance*, T*) {
    __push_heap(first, Distance((last - first) - 1), Distance(0), 
		T(*(last - 1)));
}

template <class RandomAccessIterator>
inline void push_heap(RandomAccessIterator first, RandomAccessIterator last) {
    __push_heap_aux(first, last, distance_type(first), value_type(first));
}

template <class RandomAccessIterator, class Distance, class T, class Compare>
void __push_heap(RandomAccessIterator first, Distance holeIndex,
		 Distance topIndex, T value, Compare comp) {
    Distance parent = (holeIndex - 1) / 2;
    while (holeIndex > topIndex && comp(*(first + parent), value)) {
	*(first + holeIndex) = *(first + parent);
	holeIndex = parent;
	parent = (holeIndex - 1) / 2;
    }
    *(first + holeIndex) = value;
}

template <class RandomAccessIterator, class Compare, class Distance, class T>
inline void __push_heap_aux(RandomAccessIterator first,
			    RandomAccessIterator last, Compare comp,
			    Distance*, T*) {
    __push_heap(first, Distance((last - first) - 1), Distance(0), 
		T(*(last - 1)), comp);
}

template <class RandomAccessIterator, class Compare>
inline void push_heap(RandomAccessIterator first, RandomAccessIterator last,
		      Compare comp) {
    __push_heap_aux(first, last, comp, distance_type(first), value_type(first));
}

template <class RandomAccessIterator, class Distance, class T>
void __adjust_heap(RandomAccessIterator first, Distance holeIndex,
		   Distance len, T value) {
    Distance topIndex = holeIndex;
    Distance secondChild = 2 * holeIndex + 2;
    while (secondChild < len) {
	if (*(first + secondChild) < *(first + (secondChild - 1)))
	    secondChild--;
	*(first + holeIndex) = *(first + secondChild);
	holeIndex = secondChild;
	secondChild = 2 * (secondChild + 1);
    }
    if (secondChild == len) {
	*(first + holeIndex) = *(first + (secondChild - 1));
	holeIndex = secondChild - 1;
    }
    __push_heap(first, holeIndex, topIndex, value);
}

template <class RandomAccessIterator, class T, class Distance>
inline void __pop_heap(RandomAccessIterator first, RandomAccessIterator last,
		       RandomAccessIterator result, T value, Distance*) {
    *result = *first;
    __adjust_heap(first, Distance(0), Distance(last - first), value);
}

template <class RandomAccessIterator, class T>
inline void __pop_heap_aux(RandomAccessIterator first,
			   RandomAccessIterator last, T*) {
    __pop_heap(first, last - 1, last - 1, T(*(last - 1)), distance_type(first));
}

template <class RandomAccessIterator>
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last) {
    __pop_heap_aux(first, last, value_type(first));
}

template <class RandomAccessIterator, class Distance, class T, class Compare>
void __adjust_heap(RandomAccessIterator first, Distance holeIndex,
		   Distance len, T value, Compare comp) {
    Distance topIndex = holeIndex;
    Distance secondChild = 2 * holeIndex + 2;
    while (secondChild < len) {
	if (comp(*(first + secondChild), *(first + (secondChild - 1))))
	    secondChild--;
	*(first + holeIndex) = *(first + secondChild);
	holeIndex = secondChild;
	secondChild = 2 * (secondChild + 1);
    }
    if (secondChild == len) {
	*(first + holeIndex) = *(first + (secondChild - 1));
	holeIndex = secondChild - 1;
    }
    __push_heap(first, holeIndex, topIndex, value, comp);
}

template <class RandomAccessIterator, class T, class Compare, class Distance>
inline void __pop_heap(RandomAccessIterator first, RandomAccessIterator last,
		       RandomAccessIterator result, T value, Compare comp,
		       Distance*) {
    *result = *first;
    __adjust_heap(first, Distance(0), Distance(last - first), value, comp);
}

template <class RandomAccessIterator, class T, class Compare>
inline void __pop_heap_aux(RandomAccessIterator first,
			   RandomAccessIterator last, T*, Compare comp) {
    __pop_heap(first, last - 1, last - 1, T(*(last - 1)), comp,
	       distance_type(first));
}

template <class RandomAccessIterator, class Compare>
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last,
		     Compare comp) {
    __pop_heap_aux(first, last, value_type(first), comp);
}

template <class RandomAccessIterator, class T, class Distance>
void __make_heap(RandomAccessIterator first, RandomAccessIterator last, T*,
		 Distance*) {
    if (last - first < 2) return;
    Distance len = last - first;
    Distance parent = (len - 2)/2;
    
    while (true) {
	__adjust_heap(first, parent, len, T(*(first + parent)));
	if (parent == 0) return;
	parent--;
    }
}

template <class RandomAccessIterator>
inline void make_heap(RandomAccessIterator first, RandomAccessIterator last) {
    __make_heap(first, last, value_type(first), distance_type(first));
}

template <class RandomAccessIterator, class Compare, class T, class Distance>
void __make_heap(RandomAccessIterator first, RandomAccessIterator last,
		 Compare comp, T*, Distance*) {
    if (last - first < 2) return;
    Distance len = last - first;
    Distance parent = (len - 2)/2;
    
    while (true) {
	__adjust_heap(first, parent, len, T(*(first + parent)), comp);
	if (parent == 0) return;
	parent--;
    }
}

template <class RandomAccessIterator, class Compare>
inline void make_heap(RandomAccessIterator first, RandomAccessIterator last,
		      Compare comp) {
    __make_heap(first, last, comp, value_type(first), distance_type(first));
}

template <class RandomAccessIterator>
void sort_heap(RandomAccessIterator first, RandomAccessIterator last) {
    while (last - first > 1) pop_heap(first, last--);
}

template <class RandomAccessIterator, class Compare>
void sort_heap(RandomAccessIterator first, RandomAccessIterator last,
	       Compare comp) {
    while (last - first > 1) pop_heap(first, last--, comp);
}

#endif