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/* Implementation for Objective-C Heap object
Copyright (C) 1993 Free Software Foundation, Inc.
Written by: R. Andrew McCallum <mccallum@cs.rochester.edu>
Dept. of Computer Science, U. of Rochester, Rochester, NY 14627
This file is part of the GNU Objective-C Collection library.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <coll/Heap.h>
#include <coll/ArrayPrivate.h>
#define HEAP_PARENT(i) (i/2)
#define HEAP_LEFT(i) (2 * i)
#define HEAP_RIGHT(i) ((2 * i) + 1)
@implementation Heap
/* We could take out the recursive call to make it a little more efficient */
- heapifyFromIndex: (unsigned)index
{
unsigned right, left, largest;
elt tmp;
right = HEAP_RIGHT(index);
left = HEAP_LEFT(index);
if (left <= _count
&& COMPARE_ELEMENTS(_contents_array[left],_contents_array[index]) > 0)
largest = left;
else
largest = index;
if (right <= _count
&& COMPARE_ELEMENTS(_contents_array[right],_contents_array[largest]) > 0)
largest = right;
if (largest != index)
{
tmp = _contents_array[index];
_contents_array[index] = _contents_array[largest];
_contents_array[largest] = tmp;
[self heapifyFromIndex:largest];
}
return self;
}
- heapify
{
int i;
// could use objc_msg_lookup here;
for (i = _count / 2; i >= 1; i--)
[self heapifyFromIndex:i];
return self;
}
- (elt) removeFirstElement
{
elt ret;
if (_count == 0)
NO_ELEMENT_FOUND_ERROR();
ret = _contents_array[0];
_contents_array[0] = _contents_array[_count-1];
decrementCount(self);
[self heapifyFromIndex:0];
return ret;
}
- addElement: (elt)newElement
{
int i;
incrementCount(self);
for (i = _count-1;
i > 0
&& COMPARE_ELEMENTS(_contents_array[HEAP_PARENT(i)], newElement) < 0;
i = HEAP_PARENT(i))
{
_contents_array[i] = _contents_array[HEAP_PARENT(i)];
}
_contents_array[i] = newElement;
return self;
}
@end
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