/*
 * Copyright  1999-2004 The Apache Software Foundation.
 *
 *  Licensed 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.
 *
 */
package org.apache.xml.security.utils;

import org.apache.xpath.CachedXPathAPI;
import org.w3c.dom.Document;

/**
 * @author Raul Benito
 */
public class CachedXPathAPIHolder {

    static ThreadLocal  local=new ThreadLocal();
    static ThreadLocal localDoc=new ThreadLocal();
  
    /**
     * Sets the doc for the xpath transformation. Resets the cache if needed
     * @param doc
     */
    public static void setDoc(Document doc) {                    
        if (localDoc.get()!=doc) {
            CachedXPathAPI cx=(CachedXPathAPI)local.get();
            if (cx==null) {
                cx=new CachedXPathAPI();
                local.set(cx);
                localDoc.set(doc);
                return;
            }
            //Different docs reset.
            cx.getXPathContext().reset();
            localDoc.set(doc);                     
        }		
    }

    /**
     * @return the cachexpathapi for this thread
     */
    public static CachedXPathAPI getCachedXPathAPI() {        
        CachedXPathAPI cx=(CachedXPathAPI)local.get();        
        if (cx==null) {
            cx=new CachedXPathAPI();
            local.set(cx);
            localDoc.set(null);            
        }
    	return cx;
    }
}