package org.apache.velocity.anakia;
/*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2001 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 acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Velocity", 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 names without prior written
* permission of the Apache Group.
*
* 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. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
import com.werken.xpath.XPath;
import java.util.Map;
import java.util.WeakHashMap;
/**
* Provides a cache for XPath expressions. Used by {@link NodeList} and
* {@link AnakiaElement} to minimize XPath parsing in their
* <code>selectNodes()</code> methods.
*
* @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a>
* @version $Id: XPathCache.java,v 1.1 2001/08/08 04:30:47 jon Exp $
*/
class XPathCache
{
// Cache of already parsed XPath expressions, keyed by String representations
// of the expression as passed to getXPath().
private static final Map XPATH_CACHE = new WeakHashMap();
private XPathCache()
{
}
/**
* Returns an XPath object representing the requested XPath expression.
* A cached object is returned if it already exists for the requested expression.
* @param xpathString the XPath expression to parse
* @return the XPath object that represents the parsed XPath expression.
*/
static XPath getXPath(String xpathString)
{
XPath xpath = null;
synchronized(XPATH_CACHE)
{
xpath = (XPath)XPATH_CACHE.get(xpathString);
if(xpath == null)
{
xpath = new XPath(xpathString);
XPATH_CACHE.put(xpathString, xpath);
}
}
return xpath;
}
}