XMLXpath.java

/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
 * (c) 2001 - 2013 OpenPlans
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */

package org.geoserver.security.xml;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.xml.namespace.NamespaceContext;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;

import static org.geoserver.security.xml.XMLConstants.*;

/**
 * This class is a base class for concrete implemenations
 * 
 * The main purpose is to serve as registry of
 * precompiled {@link XPathExpression} objects
 * 
 * 
 * @author christian
 *
 */
public abstract class XMLXpath {
    
    
    /**
     * Inner class providing a {@link NamespaceContext}
     * implementation
     * 
     * @author christian
     *
     */
    public class NamespaceContextImpl implements NamespaceContext {
        private Map<String,String> prefix_ns_Map = new HashMap<String,String>();
        private Map<String,String> ns_prefix_Map = new HashMap<String,String>();
        
        public String getNamespaceURI(String prefix) {
            return prefix_ns_Map.get(prefix);
        }

        public String getPrefix(String namespaceURI) {
            return ns_prefix_Map.get(namespaceURI);
        }

        public Iterator getPrefixes(String namespaceURI) {
            return prefix_ns_Map.keySet().iterator();
        }
        
        public void register(String prefix, String ns) {
            prefix_ns_Map.put(prefix, ns);
            ns_prefix_Map.put(ns,prefix);
        }        
    }

    
    /**
     * XML name space context for user/group store
     */
    protected NamespaceContextImpl urContext;
    /**
     * XML name space context for role store
     */
    protected NamespaceContextImpl rrContext;

       
    protected XMLXpath() {
        
        urContext=new NamespaceContextImpl();
        urContext.register(NSP_UR, NS_UR);
        
        rrContext=new NamespaceContextImpl();
        rrContext.register(NSP_RR, NS_RR);

    }
    
    /**
     * Compile XPath Strings to {@link XPathExpression}
     * @param xpath
     * @param expression
     *
     */
    protected XPathExpression compile(XPath xpath,String expression) {
        try {
            return xpath.compile(expression);
        } catch (XPathExpressionException e) {
            // This should never happen
            throw new RuntimeException(e);
        }
    }

    /**
     * Creates a relatvie XPathExpression for
     * a XML attribute, needs name space prefix 
     * 
     * @param xpath
     * @param attrName
     * @param prefix
     *
     */
    protected XPathExpression compileRelativeAttribute(XPath xpath,String attrName,String prefix) {        
        //return compile(xpath,"@"+prefix+":"+attrName);
        return compile(xpath,"@"+attrName);
    }
        
}