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SplayTreeMap.java

package ca.mcgill.sable.util;

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SableUtil, a clean room implementation of the Collection API.     *
 * Copyright (C) 1997, 1998 Etienne Gagnon (gagnon@sable.mcgill.ca). *
 * All rights reserved.                                              *
 *                                                                   *
 * This work was done as a project of the Sable Research Group,      *
 * School of Computer Science, McGill University, Canada             *
 * (http://www.sable.mcgill.ca/).  It is understood that any         *
 * modification not identified as such is not covered by the         *
 * preceding statement.                                              *
 *                                                                   *
 * This work 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 work 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., 59 Temple Place - Suite 330,      *
 * Boston, MA  02111-1307, USA.                                      *
 *                                                                   *
 * To submit a bug report, send a comment, or get the latest news on *
 * this project and other Sable Research Group projects, please      *
 * visit the web site: http://www.sable.mcgill.ca/                   *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 Reference Version
 -----------------
 This is the latest official version on which this file is based.
 The reference version is: $SableUtilVersion: 1.11 $

 Change History
 --------------
 A) Notes:

 Please use the following template.  Most recent changes should
 appear at the top of the list.

 - Modified on [date (March 1, 1900)] by [name]. [(*) if appropriate]
   [description of modification].

 Any Modification flagged with "(*)" was done as a project of the
 Sable Research Group, School of Computer Science,
 McGill University, Canada (http://www.sable.mcgill.ca/).

 You should add your copyright, using the following template, at
 the top of this file, along with other copyrights.

 *                                                                   *
 * Modifications by [name] are                                       *
 * Copyright (C) [year(s)] [your name (or company)].  All rights     *
 * reserved.                                                         *
 *                                                                   *

 B) Changes:

 - Modified on June 7, 1998 by Etienne Gagnon (gagnon@sable.mcgill.ca). (*)
   Changed the license.
*/

import ca.mcgill.sable.util.Map.Entry;

public class SplayTreeMap extends AbstractMap
{
    private int size;
    private Comparator comparator;
    private Node root;
    private boolean toggle;
    private Collection entries;
    private transient int modCount;

    private class EntryCollection extends AbstractCollection
    {
        public int size()
        {
            return size;
        }

        public Iterator iterator()
        {
            return new EntryIterator();
        }
    }

    private class EntryIterator implements Iterator
    {
        private Node node;
        private Object lastKey;
        private int localModCount = modCount;

        EntryIterator()
        {
            node = root;

            while((node != null) && (node.getLeft() != null))
            {
                node = node.getLeft();
            }
        }

        public boolean hasNext()
        {
            if(localModCount != modCount)
            {
                throw new ConcurrentModificationException();
            }

            return node != null;
        }

        public Object next()
        {
            if(localModCount != modCount)
            {
                throw new ConcurrentModificationException();
            }

            lastKey = node.getKey();
            Object result = node;

            if(node.getRight() != null)
            {
                node = node.getRight();

                while(node.getLeft() != null)
                {
                    node = node.getLeft();
                }
            }
            else
            {
                Node child = node;
                node = node.getParent();

                while((node != null) && (child == node.getRight()))
                {
                    child = node;
                    node = node.getParent();
                }
            }

            return result;
        }

        public void remove()
        {
            if(localModCount != modCount)
            {
                throw new ConcurrentModificationException();
            }

            if(lastKey == null)
            {
                throw new java.util.NoSuchElementException();
            }

            SplayTreeMap.this.remove(lastKey);
            localModCount = modCount;
            lastKey = null;
        }
    }

    private static class Node extends AbstractEntry
    {
        private Object key;
        private Object value;

        private Node left;
        private Node right;
        private Node parent;

        Node(Object key, Object value)
        {
            if((key == null) || (value == null))
            {
                throw new NullPointerException();
            }

            this.key = key;
            this.value = value;
        }

        public Object getKey()
        {
            return key;
        }

        public Object getValue()
        {
            return value;
        }

        public Object setValue(Object value)
        {
            if(value == null)
            {
                throw new NullPointerException();
            }

            Object oldValue = this.value;
            this.value = value;

            return oldValue;
        }

        Node getLeft()
        {
            return left;
        }

        void setLeft(Node node)
        {
            if(left != null)
            {
                left.parent = null;
            }

            if(node != null)
            {
                if(node.parent != null)
                {
                    node.parent.removeChild(node);
                }

                node.parent = this;
            }

            left = node;
        }

        Node getRight()
        {
            return right;
        }

        void setRight(Node node)
        {
            if(right != null)
            {
                right.parent = null;
            }

            if(node != null)
            {
                if(node.parent != null)
                {
                    node.parent.removeChild(node);
                }

                node.parent = this;
            }

            right = node;
        }

        Node getParent()
        {
            return parent;
        }

        private void removeChild(Node node)
        {
            if(left == node)
            {
                setLeft(null);
            }

            if(right == node)
            {
                setRight(null);
            }
        }
    }
    public SplayTreeMap()
    {
    }
    public SplayTreeMap(Comparator comparator)
    {
        this.comparator = comparator;
    }
    public SplayTreeMap(Map map)
    {
        for(Iterator i = map.entries().iterator(); i.hasNext();)
        {
            Entry e = (Entry) i.next();
            put(e.getKey(), e.getValue());
        }
    }
    public SplayTreeMap(Map map, Comparator comparator)
    {
        this.comparator = comparator;

        for(Iterator i = map.entries().iterator(); i.hasNext();)
        {
            Entry e = (Entry) i.next();
            put(e.getKey(), e.getValue());
        }
    }
    public void clear()
    {
        modCount++;
        root = null;
    }
    public Object clone()
    {
        return new SplayTreeMap(this, comparator);
    }
    private int compare(Object key1, Object key2)
    {
        if(comparator != null)
        {
            return comparator.compare(key1, key2);
        }

        return ((Comparable) key1).compareTo(key2);
    }
    public boolean containsKey(Object key)
    {
        if(key == null)
        {
            throw new NullPointerException();
        }

        Node node = find(key);

        return node != null;
    }
    private Object delete(Object key)
    {
        Node node = root;
        Node lastVisited = null;

        while(node != null)
        {
            lastVisited = node;

            int comp = compare(key, node.getKey());

            if(comp == 0)
            {
                if(node.getLeft() == null)
                {
                    Node right = node.getRight();

                    if(node.getParent() == null)
                    {
                        node.setRight(null);
                        root = right;
                        return node.getValue();
                    }

                    Node parent = node.getParent();

                    if(node == parent.getLeft())
                    {
                        parent.setLeft(right);
                    }
                    else
                    {
                        parent.setRight(right);
                    }

                    splay(right);
                    return node.getValue();
                }

                if(node.getRight() == null)
                {
                    Node left = node.getLeft();

                    if(node.getParent() == null)
                    {
                        node.setLeft(null);
                        root = left;
                        return node.getValue();
                    }

                    Node parent = node.getParent();

                    if(node == parent.getRight())
                    {
                        parent.setRight(left);
                    }
                    else
                    {
                        parent.setLeft(left);
                    }

                    splay(left);
                    return node.getValue();
                }

                Node leaf;

                toggle = !toggle;
                if(toggle)
                {
                    leaf = node.getRight();

                    while(leaf.getLeft() != null)
                    {
                        leaf = leaf.getLeft();
                    }
                }
                else
                {
                    leaf = node.getLeft();

                    while(leaf.getRight() != null)
                    {
                        leaf = leaf.getRight();
                    }
                }

                delete(leaf.getKey());

                if(node.getParent() == null)
                {
                    leaf.setRight(node.getRight());
                    leaf.setLeft(node.getLeft());
                    root = leaf;
                    return node.getValue();
                }

                Node parent = node.getParent();

                if(node == parent.getLeft())
                {
                    parent.setLeft(leaf);
                }
                else
                {
                    parent.setRight(leaf);
                }

                leaf.setRight(node.getRight());
                leaf.setLeft(node.getLeft());

                splay(leaf);
                return node.getValue();
            }

            if(comp < 0)
            {
                node = node.getLeft();
            }
            else
            {
                node = node.getRight();
            }
        }

        splay(lastVisited);
        return null;
    }
    public Collection entries()
    {
        if(entries == null)
        {
            entries = new EntryCollection();
        }

        return entries;
    }
    private Node find(Object key)
    {
        Node node = root;
        Node lastVisited = null;

        while(node != null)
        {
            lastVisited = node;

            int comp = compare(key, node.getKey());

            if(comp == 0)
            {
                splay(node);
                return node;
            }

            if(comp < 0)
            {
                node = node.getLeft();
            }
            else
            {
                node = node.getRight();
            }
        }

        splay(lastVisited);
        return null;
    }
    public Object get(Object key)
    {
        if(key == null)
        {
            throw new NullPointerException();
        }

        Node node = find(key);

        if(node != null)
        {
            return node.getValue();
        }

        return null;
    }
    public Comparator getComparator()
    {
        return comparator;
    }
    private Object insert(Object key, Object value)
    {
        Node node = root;
        Node lastVisited = null;

        while(node != null)
        {
            lastVisited = node;

            int comp = compare(key, node.getKey());

            if(comp == 0)
            {
                Object oldValue = node.getValue();
                node.setValue(value);
                splay(node);
                return oldValue;
            }

            if(comp < 0)
            {
                node = node.getLeft();
            }
            else
            {
                node = node.getRight();
            }
        }

        if(lastVisited != null)
        {
            int comp = compare(key, lastVisited.getKey());

            if(comp < 0)
            {
                lastVisited.setLeft(new Node(key, value));
                splay(lastVisited.getLeft());
                return null;
            }
            else
            {
                lastVisited.setRight(new Node(key, value));
                splay(lastVisited.getRight());
                return null;
            }
        }

        compare(key, key);
        root = new Node(key, value);
        return null;
    }
    public Object put(Object key, Object value)
    {
        modCount++;
        Object result = insert(key, value);

        if(result == null)
        {
            size++;
        }

        return result;
    }
    public Object remove(Object key)
    {
        modCount++;
        Object result = delete(key);

        if(result != null)
        {
            size--;
        }

        return result;
    }
    public int size()
    {
        return size;
    }
    private void splay(Node node)
    {
        if(node == null)
        {
            return;
        }

        while(node.getParent() != null)
        {
            Node parent = node.getParent();
            Node grandParent = parent.getParent();

            if(grandParent == null)
            {
                if(node == parent.getLeft())
                {
                    parent.setLeft(node.getRight());
                    node.setRight(parent);
                }
                else
                {
                    parent.setRight(node.getLeft());
                    node.setLeft(parent);
                }
            }
            else
            {
                Node grandGrandParent = grandParent.getParent();
                boolean grandParentIsLeft = false;

                if(grandGrandParent != null)
                {
                    if(grandParent == grandGrandParent.getLeft())
                    {
                        grandParentIsLeft = true;
                    }
                }

                if(parent == grandParent.getLeft())
                {
                    if(node == parent.getLeft())
                    {
                        grandParent.setLeft(parent.getRight());
                        parent.setRight(grandParent);
                        parent.setLeft(node.getRight());
                        node.setRight(parent);
                    }
                    else
                    {
                        grandParent.setLeft(node.getRight());
                        node.setRight(grandParent);
                        parent.setRight(node.getLeft());
                        node.setLeft(parent);
                    }
                }
                else
                {
                    if(node == parent.getRight())
                    {
                        grandParent.setRight(parent.getLeft());
                        parent.setLeft(grandParent);
                        parent.setRight(node.getLeft());
                        node.setLeft(parent);
                    }
                    else
                    {
                        grandParent.setRight(node.getLeft());
                        node.setLeft(grandParent);
                        parent.setLeft(node.getRight());
                        node.setRight(parent);
                    }
                }

                if(grandGrandParent != null)
                {
                    if(grandParentIsLeft)
                    {
                        grandGrandParent.setLeft(node);
                    }
                    else
                    {
                        grandGrandParent.setRight(node);
                    }
                }
            }
        }

        root = node;
    }
}

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