/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 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.xml.utils;
/**
* <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
{
/** Size of the m_nextChar array. */
public static final int ALPHA_SIZE = 128;
/** The root node of the tree. */
Node m_Root;
/**
* Construct the trie.
*/
public Trie()
{
m_Root = new Node();
}
/**
* Put an object into the trie for lookup.
*
* @param key must be a 7-bit ASCII string
* @param value any java object.
*
* @return The old object that matched key, or null.
*/
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;
}
/**
* Get an object that matches the key.
*
* @param key must be a 7-bit ASCII string
*
* @return The object that matches the key, or null.
*/
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;
}
/**
* <meta name="usage" content="internal"/>
* The node representation for the trie.
*/
class Node
{
/**
* Constructor, creates a Node[ALPHA_SIZE].
*/
Node()
{
m_nextChar = new Node[ALPHA_SIZE];
m_Value = null;
}
/** The next nodes. */
Node m_nextChar[];
/** The value. */
Object m_Value;
}
}