/*
Copyright 2008-2010 Gephi
Authors : Mathieu Bastian <mathieu.bastian@gephi.org>
Website : http://www.gephi.org
This file is part of Gephi.
Gephi is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Gephi 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with Gephi. If not, see <http://www.gnu.org/licenses/>.
*/
package org.gephi.utils.collection.avl;
import java.util.Iterator;
import org.gephi.utils.collection.avl.ResetableIterator;
/**
* Simple AVL Tree storing items of {@link AVLItem} class. It uses the <code>getNumber()</code> method to
* get item's key. With the iterator, nodes in the tree will be returned in a ascending order.
* <p>
* The AVL tree implementaion is based on a iterative method and guarantee O(ln(n)) access.
* @author Mathieu Bastian
*/
public class SimpleAVLTree implements Iterable<AVLItem> {
protected SimpleAVLNode root;
protected int count;
public boolean add(AVLItem item) {
SimpleAVLNode p = this.root;
if (p == null) {
this.root = new SimpleAVLNode(item);
} else {
while (true) {
int c = item.getNumber() - p.item.getNumber();
if (c < 0) {
if (p.left != null) {
p = p.left;
} else {
p.left = new SimpleAVLNode(item, p);
p.balance--;
break;
}
} else if (c > 0) {
if (p.right != null) {
p = p.right;
} else {
p.right = new SimpleAVLNode(item, p);
p.balance++;
break;
}
} else {
return false;
}
}
while ((p.balance != 0) && (p.parent != null)) {
if (p.parent.left == p) {
p.parent.balance--;
} else {
p.parent.balance++;
}
p = p.parent;
if (p.balance == -2) {
SimpleAVLNode x = p.left;
if (x.balance == -1) {
x.parent = p.parent;
if (p.parent == null) {
this.root = x;
} else {
if (p.parent.left == p) {
p.parent.left = x;
} else {
p.parent.right = x;
}
}
p.left = x.right;
if (p.left != null) {
p.left.parent = p;
}
x.right = p;
p.parent = x;
x.balance = 0;
p.balance = 0;
} else {
SimpleAVLNode w = x.right;
w.parent = p.parent;
if (p.parent == null) {
this.root = w;
} else {
if (p.parent.left == p) {
p.parent.left = w;
} else {
p.parent.right = w;
}
}
x.right = w.left;
if (x.right != null) {
x.right.parent = x;
}
p.left = w.right;
if (p.left != null) {
p.left.parent = p;
}
w.left = x;
w.right = p;
x.parent = w;
p.parent = w;
if (w.balance == -1) {
x.balance = 0;
p.balance = 1;
} else if (w.balance == 0) {
x.balance = 0;
p.balance = 0;
} else // w.balance == 1
{
x.balance = -1;
p.balance = 0;
}
w.balance = 0;
}
break;
} else if (p.balance == 2) {
SimpleAVLNode x = p.right;
if (x.balance == 1) {
x.parent = p.parent;
if (p.parent == null) {
this.root = x;
} else {
if (p.parent.left == p) {
p.parent.left = x;
} else {
p.parent.right = x;
}
}
p.right = x.left;
if (p.right != null) {
p.right.parent = p;
}
x.left = p;
p.parent = x;
x.balance = 0;
p.balance = 0;
} else {
SimpleAVLNode w = x.left;
w.parent = p.parent;
if (p.parent == null) {
this.root = w;
} else {
if (p.parent.left == p) {
p.parent.left = w;
} else {
p.parent.right = w;
}
}
x.left = w.right;
if (x.left != null) {
x.left.parent = x;
}
p.right = w.left;
if (p.right != null) {
p.right.parent = p;
}
w.right = x;
w.left = p;
x.parent = w;
p.parent = w;
if (w.balance == 1) {
x.balance = 0;
p.balance = -1;
} else if (w.balance == 0) {
x.balance = 0;
p.balance = 0;
} else // w.balance == -1
{
x.balance = 1;
p.balance = 0;
}
w.balance = 0;
}
break;
}
}
}
this.count++;
return true;
}
public boolean remove(AVLItem item) {
return this.remove(item.getNumber());
}
public boolean remove(int number) {
SimpleAVLNode p = this.root;
while (p != null) {
int c = number - p.item.getNumber();
if (c < 0) {
p = p.left;
} else if (c > 0) {
p = p.right;
} else {
SimpleAVLNode y; // node from which rebalancing begins
int choice = 0; //0:Done 1:Left 2:Right
if (p.right == null) // Case 1: p has no right child
{
if (p.left != null) {
p.left.parent = p.parent;
}
if (p.parent == null) {
this.root = p.left;
count--;
return true;
}
if (p == p.parent.left) {
p.parent.left = p.left;
y = p.parent;
choice = 1;
// goto LeftDelete;
} else {
p.parent.right = p.left;
y = p.parent;
choice = 2;
//goto RightDelete;
}
} else if (p.right.left == null) // Case 2: p's right child has no left child
{
if (p.left != null) {
p.left.parent = p.right;
p.right.left = p.left;
}
p.right.balance = p.balance;
p.right.parent = p.parent;
if (p.parent == null) {
this.root = p.right;
} else {
if (p == p.parent.left) {
p.parent.left = p.right;
} else {
p.parent.right = p.right;
}
}
y = p.right;
choice = 2;
//goto RightDelete;
} else // Case 3: p's right child has a left child
{
SimpleAVLNode s = p.right.left;
while (s.left != null) {
s = s.left;
}
if (p.left != null) {
p.left.parent = s;
s.left = p.left;
}
s.parent.left = s.right;
if (s.right != null) {
s.right.parent = s.parent;
}
p.right.parent = s;
s.right = p.right;
y = s.parent; // for rebalacing, must be set before we change s.parent
s.balance = p.balance;
s.parent = p.parent;
if (p.parent == null) {
this.root = s;
} else {
if (p == p.parent.left) {
p.parent.left = s;
} else {
p.parent.right = s;
}
}
choice = 1;
// goto LeftDelete;
}
// rebalancing begins
while (choice != 0) {
if (choice == 1) {
//LeftDelete:
y.balance++;
if (y.balance == 1) {
//goto Done;
choice = 0;
} else if (y.balance == 2) {
SimpleAVLNode x = y.right;
if (x.balance == -1) {
SimpleAVLNode w = x.left;
w.parent = y.parent;
if (y.parent == null) {
this.root = w;
} else {
if (y.parent.left == y) {
y.parent.left = w;
} else {
y.parent.right = w;
}
}
x.left = w.right;
if (x.left != null) {
x.left.parent = x;
}
y.right = w.left;
if (y.right != null) {
y.right.parent = y;
}
w.right = x;
w.left = y;
x.parent = w;
y.parent = w;
if (w.balance == 1) {
x.balance = 0;
y.balance = -1;
} else if (w.balance == 0) {
x.balance = 0;
y.balance = 0;
} else // w.balance == -1
{
x.balance = 1;
y.balance = 0;
}
w.balance = 0;
y = w; // for next iteration
} else {
x.parent = y.parent;
if (y.parent != null) {
if (y.parent.left == y) {
y.parent.left = x;
} else {
y.parent.right = x;
}
} else {
this.root = x;
}
y.right = x.left;
if (y.right != null) {
y.right.parent = y;
}
x.left = y;
y.parent = x;
if (x.balance == 0) {
x.balance = -1;
y.balance = 1;
//goto Done
choice = 0;
} else {
x.balance = 0;
y.balance = 0;
y = x; // for next iteration
}
}
}
} else if (choice == 2) {
//goto LoopTest;
//RightDelete:
y.balance--;
if (y.balance == -1) {
choice = 0;
//goto Done;
} else if (y.balance == -2) {
SimpleAVLNode x = y.left;
if (x.balance == 1) {
SimpleAVLNode w = x.right;
w.parent = y.parent;
if (y.parent == null) {
this.root = w;
} else {
if (y.parent.left == y) {
y.parent.left = w;
} else {
y.parent.right = w;
}
}
x.right = w.left;
if (x.right != null) {
x.right.parent = x;
}
y.left = w.right;
if (y.left != null) {
y.left.parent = y;
}
w.left = x;
w.right = y;
x.parent = w;
y.parent = w;
if (w.balance == -1) {
x.balance = 0;
y.balance = 1;
} else if (w.balance == 0) {
x.balance = 0;
y.balance = 0;
} else // w.balance == 1
{
x.balance = -1;
y.balance = 0;
}
w.balance = 0;
y = w; // for next iteration
} else {
x.parent = y.parent;
if (y.parent != null) {
if (y.parent.left == y) {
y.parent.left = x;
} else {
y.parent.right = x;
}
} else {
this.root = x;
}
y.left = x.right;
if (y.left != null) {
y.left.parent = y;
}
x.right = y;
y.parent = x;
if (x.balance == 0) {
x.balance = 1;
y.balance = -1;
choice = 0;
//goto Done;
} else {
x.balance = 0;
y.balance = 0;
y = x; // for next iteration
}
}
}
}
if (choice == 0) {
this.count--;
return true;
}
//LoopTest: {
if (y.parent != null) {
if (y == y.parent.left) {
y = y.parent;
choice = 1;
// goto LeftDelete;
} else {
y = y.parent;
choice = 2;
//goto RightDelete;
}
} else {
//Done
this.count--;
return true;
}
}
}
}
return false;
}
public boolean contains(AVLItem item) {
SimpleAVLNode p = this.root;
while (p != null) {
int c = item.getNumber() - p.item.getNumber();
if (c < 0) {
p = p.left;
} else if (c > 0) {
p = p.right;
} else {
return true;
}
}
return false;
}
public AVLItem get(int number) {
SimpleAVLNode p = this.root;
while (p != null) {
int c = number - p.item.getNumber();
if (c < 0) {
p = p.left;
} else if (c > 0) {
p = p.right;
} else {
return p.item;
}
}
return null;
}
public void clear() {
this.root = null;
this.count = 0;
}
public Iterator<AVLItem> iterator() {
return new SimpleAVLIterator(this);
}
public int getCount() {
return count;
}
private class SimpleAVLNode {
SimpleAVLNode parent;
SimpleAVLNode left;
SimpleAVLNode right;
int balance;
AVLItem item;
public SimpleAVLNode(AVLItem item) {
this.item = item;
}
public SimpleAVLNode(AVLItem item, SimpleAVLNode parent) {
this.item = item;
this.parent = parent;
}
}
private class SimpleAVLIterator implements Iterator<AVLItem>, ResetableIterator {
private SimpleAVLNode next;
private AVLItem current;
public SimpleAVLIterator() {
}
public SimpleAVLIterator(SimpleAVLNode node) {
this.next = node;
goToDownLeft();
}
public SimpleAVLIterator(SimpleAVLTree tree) {
this(tree.root);
}
public void setNode(SimpleAVLTree tree) {
this.next = tree.root;
goToDownLeft();
}
private void goToDownLeft() {
if (next != null) {
while (next.left != null) {
next = next.left;
}
}
}
public boolean hasNext() {
if (next == null) {
return false;
}
current = this.next.item;
if (next.right == null) {
while ((next.parent != null) && (next == next.parent.right)) {
this.next = this.next.parent;
}
this.next = this.next.parent;
} else {
this.next = this.next.right;
while (this.next.left != null) {
this.next = this.next.left;
}
}
return true;
}
public AVLItem next() {
return current;
}
public void remove() {
SimpleAVLTree.this.remove(current);
}
}
}