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/* Implementation for Objective-C Red-Black Tree collection object
Copyright (C) 1993, 1994, 1996 Free Software Foundation, Inc.
Written by: Andrew Kachites McCallum <mccallum@gnu.ai.mit.edu>
Date: May 1993
This file is part of the GNUstep Base 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 <gnustep/base/RBTree.h>
#include <gnustep/base/IndexedCollectionPrivate.h>
#include <gnustep/base/RBTreeNode.h>
#define NODE_IS_RED(NODE) ([NODE isRed])
#define NODE_IS_BLACK(NODE) (![NODE isRed])
/* sentinal */
static id nilRBNode;
@implementation RBTree
+ (void) initialize
{
if (self == [RBTree class])
{
nilRBNode = [[RBTreeNode alloc] init];
[nilRBNode setBlack];
}
}
- nilNode
{
return nilRBNode;
}
- (void) sortAddObject: newObject
{
id y;
[super sortAddObject: newObject];
[newObject setRed];
while (newObject != _contents_root
&& [[newObject parentNode] isRed])
{
if ([newObject parentNode] ==
[[[newObject parentNode] parentNode] leftNode])
{
y = [[[newObject parentNode] parentNode] leftNode];
if ([y isRed])
{
[[newObject parentNode] setBlack];
[y setBlack];
[[[newObject parentNode] parentNode] setRed];
newObject = [[newObject parentNode] parentNode];
}
else
{
if (newObject == [[newObject parentNode] rightNode])
{
newObject = [newObject parentNode];
[self leftRotateAroundNode:newObject];
}
[[newObject parentNode] setBlack];
[[[newObject parentNode] parentNode] setRed];
[self rightRotateAroundNode:
[[newObject parentNode] parentNode]];
}
}
else
{
y = [[[newObject parentNode] parentNode] rightNode];
if ([y isRed])
{
[[newObject parentNode] setBlack];
[y setBlack];
[[[newObject parentNode] parentNode] setRed];
newObject = [[newObject parentNode] parentNode];
}
else
{
if (newObject == [[newObject parentNode] leftNode])
{
newObject = [newObject parentNode];
[self rightRotateAroundNode:newObject];
}
[[newObject parentNode] setBlack];
[[[newObject parentNode] parentNode] setRed];
[self leftRotateAroundNode:
[[newObject parentNode] parentNode]];
}
}
}
[_contents_root setBlack];
}
- (void) _RBTreeDeleteFixup: x
{
id w;
while (x != _contents_root && NODE_IS_BLACK(x))
{
if (NODE_IS_LEFTCHILD(x))
{
w = [[x parentNode] rightNode];
if (NODE_IS_RED(w))
{
[w setBlack];
[[x parentNode] setRed];
[self leftRotateAroundNode:[x parentNode]];
w = [[x parentNode] rightNode];
}
if (NODE_IS_BLACK([w leftNode]) && NODE_IS_BLACK([w rightNode]))
{
[w setRed];
x = [x parentNode];
}
else
{
if (NODE_IS_BLACK([w rightNode]))
{
[[w leftNode] setBlack];
[w setRed];
[self rightRotateAroundNode:w];
w = [[x parentNode] rightNode];
}
if (NODE_IS_BLACK([x parentNode]))
[w setBlack];
else
[w setRed];
[[x parentNode] setBlack];
[[w rightNode] setBlack];
[self leftRotateAroundNode:[x parentNode]];
x = _contents_root;
}
}
else
{
w = [[x parentNode] leftNode];
if (NODE_IS_RED(w))
{
[w setBlack];
[[x parentNode] setRed];
[self rightRotateAroundNode:[x parentNode]];
w = [[x parentNode] leftNode];
}
if (NODE_IS_BLACK([w rightNode]) && NODE_IS_BLACK([w leftNode]))
{
[w setRed];
x = [x parentNode];
}
else
{
if (NODE_IS_BLACK([w leftNode]))
{
[[w rightNode] setBlack];
[w setRed];
[self leftRotateAroundNode:w];
w = [[x parentNode] leftNode];
}
if (NODE_IS_BLACK([x parentNode]))
[w setBlack];
else
[w setRed];
[[x parentNode] setBlack];
[[w leftNode] setBlack];
[self rightRotateAroundNode:[x parentNode]];
x = _contents_root;
}
}
}
[x setBlack];
}
- (void) removeObject: oldObject
{
id x, y;
if ([oldObject leftNode] == [self nilNode]
|| [oldObject rightNode] == [self nilNode])
y = oldObject;
else
y = [self successorOfObject: oldObject];
if ([y leftNode] != [self nilNode])
x = [y leftNode];
else
x = [y rightNode];
[x setParentNode:[y parentNode]];
if ([y parentNode] == [self nilNode])
_contents_root = x;
else
{
if (y == [[y parentNode] leftNode])
[[y parentNode] setLeftNode:x];
else
[[y parentNode] setRightNode:x];
}
if (y != oldObject)
{
/* put y in the place of oldObject */
[y setParentNode:[oldObject parentNode]];
[y setLeftNode:[oldObject leftNode]];
[y setRightNode:[oldObject rightNode]];
if (oldObject == [[oldObject parentNode] leftNode])
[[oldObject parentNode] setLeftNode:y];
else
[[oldObject parentNode] setRightNode:oldObject];
[[oldObject leftNode] setParentNode:y];
[[oldObject rightNode] setParentNode:y];
}
if (NODE_IS_BLACK(y))
[self _RBTreeDeleteFixup:x];
_count--;
/* Release ownership of the object. */
#if 0
[oldObject setRightNode: [self nilNode]];
[oldObject setLeftNode: [self nilNode]];
[oldObject setParentNode: [self nilNode]];
#else
[oldObject setLeftNode: NO_OBJECT];
[oldObject setRightNode: NO_OBJECT];
[oldObject setParentNode: NO_OBJECT];
#endif
[oldObject setBinaryTree: NO_OBJECT];
[oldObject release];
}
@end
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