modules/assembly-xml/src/main/java/org/apache/tuscany/sca/policy/xml/PolicyXPathFunction.java - tuscany-sca-2.x - Git at Google

 /*
  * 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.
  */

 package org.apache.tuscany.sca.policy.xml;

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;

 import javax.xml.XMLConstants;
 import javax.xml.namespace.NamespaceContext;
 import javax.xml.namespace.QName;
 import javax.xml.xpath.XPathFunction;
 import javax.xml.xpath.XPathFunctionException;

 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;

 /**
  * The SCA-defined XPath function
  */
 public class PolicyXPathFunction implements XPathFunction {
     private static Logger logger = Logger.getLogger(PolicyXPathFunction.class.getName());

     static final QName InterfaceRef = new QName(PolicyConstants.SCA11_NS, "InterfaceRef");
     static final QName OperationRef = new QName(PolicyConstants.SCA11_NS, "OperationRef");
     static final QName MessageRef = new QName(PolicyConstants.SCA11_NS, "MessageRef");
     static final QName IntentRefs = new QName(PolicyConstants.SCA11_NS, "IntentRefs");
     static final QName URIRef = new QName(PolicyConstants.SCA11_NS, "URIRef");

     static final Set<QName> functions =
         new HashSet<QName>(Arrays.asList(InterfaceRef, OperationRef, MessageRef, IntentRefs, URIRef));

     private NamespaceContext namespaceContext;
     private final QName functionName;

     public PolicyXPathFunction(NamespaceContext namespaceContext, QName functionName) {
         super();
         this.namespaceContext = namespaceContext;
         this.functionName = functionName;
     }

     private Node getContextNode(List args) {
         if (args.size() >= 2) {
             NodeList nodeList = (NodeList)args.get(1);
             if (nodeList.getLength() > 0) {
                 return nodeList.item(0);
             }
         }
         return null;
     }

     public Object evaluate(List args) throws XPathFunctionException {
         if (logger.isLoggable(Level.FINE)) {
             logger.fine(functionName + "(" + args + ")");
         }

         String arg = (String)args.get(0);
         Node node = getContextNode(args);
         /**
          * If the xpath expression that contains the function does not select any nodes
          * (eg IntentRefs('someIntent')), the context node passed in will be a Document.
          * In this case we need to iterate over every Node in the Document and evaluate it.
          *
          * If the xpath expression does select nodes (eg //sca:component[IntentRefs('someIntent')])
          * then xpath will call evaluate for each node and we only need to return the result for that
          * node.
          */
         if ( node instanceof Document )
         	return evaluateDocument(arg, (Document)node);
         else
         	return evaluateNode(arg, node);
     }

     public Object evaluateNode(String arg, Node node) {
         if (InterfaceRef.equals(functionName)) {
             return evaluateInterface(arg, node);
         } else if (OperationRef.equals(functionName)) {
             String[] params = arg.split("/");
             if (params.length != 2) {
                 throw new IllegalArgumentException("Invalid argument: " + arg);
             }
             String interfaceName = params[0];
             String operationName = params[1];
             return evaluateOperation(interfaceName, operationName, node);
         } else if (MessageRef.equals(functionName)) {
             String[] params = arg.split("/");
             if (params.length != 3) {
                 throw new IllegalArgumentException("Invalid argument: " + arg);
             }
             String interfaceName = params[0];
             String operationName = params[1];
             String messageName = params[2];
             return evaluateMessage(interfaceName, operationName, messageName, node);
         } else if (URIRef.equals(functionName)) {
             return evaluateURI(arg, node);
         } else if (IntentRefs.equals(functionName)) {
             String[] intents = arg.split("(\\s)+");
             return evaluateIntents(intents, node);
         } else {
             return Boolean.FALSE;
         }
     }

     private class NodeListImpl implements NodeList {

     	private ArrayList<Node> list;

 		public NodeListImpl() {
     		this.list = new ArrayList<Node>();
     	}
 		public int getLength() {
 			return this.list.size();
 		}

 		public Node item(int index) {
 			return this.list.get(index);
 		}
 		public boolean add(Node node) {
 			return this.list.add(node);

 		}

     }
     private Object evaluateDocument(String arg, Document doc) {
     	NodeListImpl retList = new NodeListImpl();
     	NodeList elements = doc.getElementsByTagName("*");
 		for ( int i=0; i < elements.getLength(); i++) {
 			Object node = evaluateNode(arg, elements.item(i));
 			if ( node != null )
 				retList.add((Node)node);
 		}
 		return retList;
 	}

 	private Boolean evaluateInterface(String interfaceName, Node node) {
         return Boolean.FALSE;
     }

     private Boolean evaluateOperation(String interfaceName, String operationName, Node node) {
         return Boolean.FALSE;
     }

     private Boolean evaluateMessage(String interfaceName, String operationName, String messageName, Node node) {
         return Boolean.FALSE;
     }

     private Boolean evaluateURI(String uri, Node node) {
         return Boolean.FALSE;
     }

     /**
      * Evaluates a single node for the given intents.
      * @param intents
      * @param node
      * @return
      */
     private Object evaluateIntents(String[] intents, Node node) {
     	if ( node == null )
     		return false;

     	if ( node.getAttributes() != null ) {
     		for  ( int i=0; i < node.getAttributes().getLength(); i++) {
     			Node attr = node.getAttributes().item(i);

     			if ( "requires".equalsIgnoreCase(attr.getNodeName())) {

     				for ( int j = 0; j < intents.length; j++ ) {
     					// Check negative intents
     					if ( intents[j].startsWith("!")) {
     						if ( matchIntent(intents[j].substring(1), attr, node.getNamespaceURI()))
     							return null;
     					} else if ( !matchIntent(intents[j], attr, node.getNamespaceURI())){
     						return null;
     					}
     				}
     				return node;
     			}

     		}
     	}

         return null;
     }


     /**
      * Determine whether the given intent is present in the "requires" attribute
      * @param intent
      * @param node
      * @param namespaceURI
      * @return
      */
 	private boolean matchIntent(String intent, Node node, String namespaceURI) {
     	String[] requires = node.getNodeValue().split("(\\s)+");
 		QName intentName = getStringAsQName(intent);


 		for ( int i=0; i < requires.length; i++ ) {
 			QName nodeName = null;
 			int idx = requires[i].indexOf(':');

 			// No prefix specified
 			if ( idx == -1 ) {
 				nodeName = new QName(namespaceURI, requires[i]);
 			} else {
 				String prefix = requires[i].substring(0, idx);
 				String name = requires[i].substring(idx + 1);
 				String ns = node.lookupNamespaceURI(prefix);
 				nodeName = new QName(ns, name, prefix);
 			}
 			if ( intentName.equals(nodeName))
 				return true;
 		}
 		return false;
 	}


 	private QName getStringAsQName(String intent) {
 		int idx = intent.indexOf(':');
 		if (idx == -1)
 			return new QName(namespaceContext.getNamespaceURI(XMLConstants.DEFAULT_NS_PREFIX), intent);

 		String prefix = intent.substring(0, idx);
 		intent = intent.substring(idx + 1);

 		return new QName(namespaceContext.getNamespaceURI(prefix), intent, prefix);

 	}


 	private static Pattern FUNCTION;
     static {
         String functionPattern = "(URIRef|InterfaceRef|OperationRef|MessageRef|IntentRefs)\\s*\\(([^\\)]*)\\)";
         FUNCTION = Pattern.compile(functionPattern);
     }

     /** Adds the node as an argument to the XPath function.
      * Required in order to have access to the NodeList within the function
      */
     public static String normalize(String attachTo, String scaPrefix) {
     	// Get rid of any whitespace
     	attachTo = attachTo.trim();

         Matcher matcher = FUNCTION.matcher(attachTo);
         boolean result = matcher.find();
         if (result) {
             StringBuffer sb = new StringBuffer();
             do {
                 String function = matcher.group(1);
                 String args = matcher.group(2);
                 if ( (matcher.start() == 0) || (attachTo.charAt( matcher.start() -1) != ':' )) {
                 	function = scaPrefix + ":" + function;
                 }
                 String replacement = null;
                 if (args.trim().length() > 0) {
                     replacement = function + "(" + args + "," + "self::node())";
                 } else {
                     replacement = function + "(self::node())";
                 }
                 matcher.appendReplacement(sb, replacement);
                 result = matcher.find();
             } while (result);

             matcher.appendTail(sb);
             return sb.toString();
         }
         return attachTo;
     }

 }
	/*
	* 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.
	*/

	package org.apache.tuscany.sca.policy.xml;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Set;
	import java.util.logging.Level;
	import java.util.logging.Logger;
	import java.util.regex.Matcher;
	import java.util.regex.Pattern;

	import javax.xml.XMLConstants;
	import javax.xml.namespace.NamespaceContext;
	import javax.xml.namespace.QName;
	import javax.xml.xpath.XPathFunction;
	import javax.xml.xpath.XPathFunctionException;

	import org.w3c.dom.Document;
	import org.w3c.dom.Node;
	import org.w3c.dom.NodeList;

	/**
	* The SCA-defined XPath function
	*/
	public class PolicyXPathFunction implements XPathFunction {
	private static Logger logger = Logger.getLogger(PolicyXPathFunction.class.getName());

	static final QName InterfaceRef = new QName(PolicyConstants.SCA11_NS, "InterfaceRef");
	static final QName OperationRef = new QName(PolicyConstants.SCA11_NS, "OperationRef");
	static final QName MessageRef = new QName(PolicyConstants.SCA11_NS, "MessageRef");
	static final QName IntentRefs = new QName(PolicyConstants.SCA11_NS, "IntentRefs");
	static final QName URIRef = new QName(PolicyConstants.SCA11_NS, "URIRef");

	static final Set<QName> functions =
	new HashSet<QName>(Arrays.asList(InterfaceRef, OperationRef, MessageRef, IntentRefs, URIRef));

	private NamespaceContext namespaceContext;
	private final QName functionName;

	public PolicyXPathFunction(NamespaceContext namespaceContext, QName functionName) {
	super();
	this.namespaceContext = namespaceContext;
	this.functionName = functionName;
	}

	private Node getContextNode(List args) {
	if (args.size() >= 2) {
	NodeList nodeList = (NodeList)args.get(1);
	if (nodeList.getLength() > 0) {
	return nodeList.item(0);
	}
	}
	return null;
	}

	public Object evaluate(List args) throws XPathFunctionException {
	if (logger.isLoggable(Level.FINE)) {
	logger.fine(functionName + "(" + args + ")");
	}

	String arg = (String)args.get(0);
	Node node = getContextNode(args);
	/**
	* If the xpath expression that contains the function does not select any nodes
	* (eg IntentRefs('someIntent')), the context node passed in will be a Document.
	* In this case we need to iterate over every Node in the Document and evaluate it.
	*
	* If the xpath expression does select nodes (eg //sca:component[IntentRefs('someIntent')])
	* then xpath will call evaluate for each node and we only need to return the result for that
	* node.
	*/
	if ( node instanceof Document )
	return evaluateDocument(arg, (Document)node);
	else
	return evaluateNode(arg, node);
	}

	public Object evaluateNode(String arg, Node node) {
	if (InterfaceRef.equals(functionName)) {
	return evaluateInterface(arg, node);
	} else if (OperationRef.equals(functionName)) {
	String[] params = arg.split("/");
	if (params.length != 2) {
	throw new IllegalArgumentException("Invalid argument: " + arg);
	}
	String interfaceName = params[0];
	String operationName = params[1];
	return evaluateOperation(interfaceName, operationName, node);
	} else if (MessageRef.equals(functionName)) {
	String[] params = arg.split("/");
	if (params.length != 3) {
	throw new IllegalArgumentException("Invalid argument: " + arg);
	}
	String interfaceName = params[0];
	String operationName = params[1];
	String messageName = params[2];
	return evaluateMessage(interfaceName, operationName, messageName, node);
	} else if (URIRef.equals(functionName)) {
	return evaluateURI(arg, node);
	} else if (IntentRefs.equals(functionName)) {
	String[] intents = arg.split("(\\s)+");
	return evaluateIntents(intents, node);
	} else {
	return Boolean.FALSE;
	}
	}

	private class NodeListImpl implements NodeList {

	private ArrayList<Node> list;

	public NodeListImpl() {
	this.list = new ArrayList<Node>();
	}
	public int getLength() {
	return this.list.size();
	}

	public Node item(int index) {
	return this.list.get(index);
	}
	public boolean add(Node node) {
	return this.list.add(node);

	}

	}
	private Object evaluateDocument(String arg, Document doc) {
	NodeListImpl retList = new NodeListImpl();
	NodeList elements = doc.getElementsByTagName("*");
	for ( int i=0; i < elements.getLength(); i++) {
	Object node = evaluateNode(arg, elements.item(i));
	if ( node != null )
	retList.add((Node)node);
	}
	return retList;
	}

	private Boolean evaluateInterface(String interfaceName, Node node) {
	return Boolean.FALSE;
	}

	private Boolean evaluateOperation(String interfaceName, String operationName, Node node) {
	return Boolean.FALSE;
	}

	private Boolean evaluateMessage(String interfaceName, String operationName, String messageName, Node node) {
	return Boolean.FALSE;
	}

	private Boolean evaluateURI(String uri, Node node) {
	return Boolean.FALSE;
	}

	/**
	* Evaluates a single node for the given intents.
	* @param intents
	* @param node
	* @return
	*/
	private Object evaluateIntents(String[] intents, Node node) {
	if ( node == null )
	return false;

	if ( node.getAttributes() != null ) {
	for ( int i=0; i < node.getAttributes().getLength(); i++) {
	Node attr = node.getAttributes().item(i);

	if ( "requires".equalsIgnoreCase(attr.getNodeName())) {

	for ( int j = 0; j < intents.length; j++ ) {
	// Check negative intents
	if ( intents[j].startsWith("!")) {
	if ( matchIntent(intents[j].substring(1), attr, node.getNamespaceURI()))
	return null;
	} else if ( !matchIntent(intents[j], attr, node.getNamespaceURI())){
	return null;
	}
	}
	return node;
	}

	}
	}

	return null;
	}



	/**
	* Determine whether the given intent is present in the "requires" attribute
	* @param intent
	* @param node
	* @param namespaceURI
	* @return
	*/
	private boolean matchIntent(String intent, Node node, String namespaceURI) {
	String[] requires = node.getNodeValue().split("(\\s)+");
	QName intentName = getStringAsQName(intent);


	for ( int i=0; i < requires.length; i++ ) {
	QName nodeName = null;
	int idx = requires[i].indexOf(':');

	// No prefix specified
	if ( idx == -1 ) {
	nodeName = new QName(namespaceURI, requires[i]);
	} else {
	String prefix = requires[i].substring(0, idx);
	String name = requires[i].substring(idx + 1);
	String ns = node.lookupNamespaceURI(prefix);
	nodeName = new QName(ns, name, prefix);
	}
	if ( intentName.equals(nodeName))
	return true;
	}
	return false;
	}


	private QName getStringAsQName(String intent) {
	int idx = intent.indexOf(':');
	if (idx == -1)
	return new QName(namespaceContext.getNamespaceURI(XMLConstants.DEFAULT_NS_PREFIX), intent);

	String prefix = intent.substring(0, idx);
	intent = intent.substring(idx + 1);

	return new QName(namespaceContext.getNamespaceURI(prefix), intent, prefix);

	}


	private static Pattern FUNCTION;
	static {
	String functionPattern = "(URIRef\|InterfaceRef\|OperationRef\|MessageRef\|IntentRefs)\\s\\(([^\\)])\\)";
	FUNCTION = Pattern.compile(functionPattern);
	}

	/** Adds the node as an argument to the XPath function.
	* Required in order to have access to the NodeList within the function
	*/
	public static String normalize(String attachTo, String scaPrefix) {
	// Get rid of any whitespace
	attachTo = attachTo.trim();

	Matcher matcher = FUNCTION.matcher(attachTo);
	boolean result = matcher.find();
	if (result) {
	StringBuffer sb = new StringBuffer();
	do {
	String function = matcher.group(1);
	String args = matcher.group(2);
	if ( (matcher.start() == 0) \|\| (attachTo.charAt( matcher.start() -1) != ':' )) {
	function = scaPrefix + ":" + function;
	}
	String replacement = null;
	if (args.trim().length() > 0) {
	replacement = function + "(" + args + "," + "self::node())";
	} else {
	replacement = function + "(self::node())";
	}
	matcher.appendReplacement(sb, replacement);
	result = matcher.find();
	} while (result);

	matcher.appendTail(sb);
	return sb.toString();
	}
	return attachTo;
	}

	}