001/**
002 * Copyright 2005-2017 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.kew.rule.xmlrouting;
017
018import javax.xml.xpath.XPath;
019import javax.xml.xpath.XPathFactory;
020import javax.xml.xpath.XPathFunctionResolver;
021
022import org.kuali.rice.kew.api.WorkflowRuntimeException;
023import org.w3c.dom.Node;
024
025
026/**
027 * Provides utilities for obtaining XPath instances which are "good-to-go" with access to the Workflow
028 * namespace and custom XPath functions.
029 * 
030 * @author Kuali Rice Team (rice.collab@kuali.org)
031 */
032public class XPathHelper {
033
034        /**
035         * Creates a new XPath instance and initializes it with the WorkflowNamespaceContext and the
036         * WorkflowFunctionResolver.
037         */
038        public static XPath newXPath() {
039                XPath xPath = XPathFactory.newInstance().newXPath();
040                xPath.setNamespaceContext(new WorkflowNamespaceContext());
041                WorkflowFunctionResolver resolver = new WorkflowFunctionResolver();
042                xPath.setXPathFunctionResolver(resolver); 
043                resolver.setXpath(xPath);
044                return xPath;
045        }
046
047        /**
048         * Creates a new XPath instances and initializes it with the WorkflowNamespaceContext and the
049         * WorkflowFunctionResolver.  Also sets the root node on the WorkflowFunctionResolver to 
050         * the given Node.  This is required for some of the functions in the function resolver
051         * to perform properly.
052         */
053        public static XPath newXPath(Node rootNode) {
054                XPath xPath = newXPath();
055                WorkflowFunctionResolver resolver = extractFunctionResolver(xPath);
056                resolver.setRootNode(rootNode);
057                return xPath;
058        }
059        
060        /**
061         * A utility to extract the WorkflowFunctionResolver from the given XPath instances.  If the XPath instance
062         * does not contain a WorkflowFunctionResolver, then this method will throw a WorkflowRuntimeException.
063         * 
064         * @throws WorkflowRuntimeException if the given XPath instance does not contain a WorklflowFunctionResolver
065         */
066        public static WorkflowFunctionResolver extractFunctionResolver(XPath xPath) {
067                XPathFunctionResolver resolver = xPath.getXPathFunctionResolver();
068                if (!hasWorkflowFunctionResolver(xPath)) {
069                        throw new WorkflowRuntimeException("The XPathFunctionResolver on the given XPath instance is not an instance of WorkflowFunctionResolver, was: " + resolver);
070                }
071                return (WorkflowFunctionResolver)resolver;
072        }
073        
074        /**
075         * Returns true if the given XPath instance has a WorkflowFunctionResolver, false otherwise.
076         */
077        public static boolean hasWorkflowFunctionResolver(XPath xPath) {
078                return xPath.getXPathFunctionResolver() instanceof WorkflowFunctionResolver;
079        }
080        
081}