package bboss.org.apache.velocity.anakia;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
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 463298 2006-10-12 16:10:32Z henning $
*/
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;
}
}