/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.xalan.xpath.xml;

/** 
 * <meta name="usage" content="internal"/>
 * A digital search trie for 7-bit ASCII text
 * The API is a subset of java.util.Hashtable
 * The key must be a 7-bit ASCII string
 * The value may be any Java Object
 */
public class Trie
{
	public static final int ALPHA_SIZE = 128;

	Node m_Root;

	public Trie()
	{
		m_Root = new Node();
	}

	public Object put(String key, Object value)
	{
  		final int len = key.length();

		Node node = m_Root;

		for (int i = 0; i< len; i++)
		{
			Node nextNode = node.m_nextChar[Character.toUpperCase(key.charAt(i))];

			if (nextNode != null)
			{
				node = nextNode;
			}
			else
			{
				for (;i<len; i++)
				{
					Node newNode = new Node();
					node.m_nextChar[Character.toUpperCase(key.charAt(i))] = newNode;
					node = newNode;
				}

				break;
			}
		}

		Object ret = node.m_Value;
		node.m_Value = value;

		return ret;
	}

	public Object get(String key)
	{
		final int len = key.length();

		Node node = m_Root;

		for (int i = 0; i< len; i++)
		{
			try
			{
				node = node.m_nextChar[Character.toUpperCase(key.charAt(i))];
			}

			catch (ArrayIndexOutOfBoundsException e)
			{
				// the key is not 7-bit ASCII so we won't find it here
				node = null;					
			}

			if (node == null)
  				return null;
  		}

		return node.m_Value;
	}

  	class Node
	{
		Node()
		{
			m_nextChar = new Node[ALPHA_SIZE];
			m_Value = null;
		}

		Node m_nextChar[];
		Object m_Value;
	}
}