| /* |
| * 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. |
| */ |
| /* |
| * $Id$ |
| */ |
| |
| package org.apache.xpath.domapi; |
| |
| import javax.xml.transform.TransformerException; |
| |
| import org.apache.xml.utils.PrefixResolver; |
| import org.apache.xpath.XPath; |
| import org.apache.xpath.res.XPATHErrorResources; |
| import org.apache.xpath.res.XPATHMessages; |
| import org.w3c.dom.DOMException; |
| import org.w3c.dom.Document; |
| import org.w3c.dom.Node; |
| import org.w3c.dom.xpath.XPathEvaluator; |
| import org.w3c.dom.xpath.XPathException; |
| import org.w3c.dom.xpath.XPathExpression; |
| import org.w3c.dom.xpath.XPathNSResolver; |
| |
| /** |
| * |
| * The class provides an implementation of XPathEvaluator according |
| * to the DOM L3 XPath Specification, Working Group Note 26 February 2004. |
| * |
| * <p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p> |
| * |
| * </p>The evaluation of XPath expressions is provided by |
| * <code>XPathEvaluator</code>, which will provide evaluation of XPath 1.0 |
| * expressions with no specialized extension functions or variables. It is |
| * expected that the <code>XPathEvaluator</code> interface will be |
| * implemented on the same object which implements the <code>Document</code> |
| * interface in an implementation which supports the XPath DOM module. |
| * <code>XPathEvaluator</code> implementations may be available from other |
| * sources that may provide support for special extension functions or |
| * variables which are not defined in this specification.</p> |
| * |
| * @see org.w3c.dom.xpath.XPathEvaluator |
| * |
| * @xsl.usage internal |
| */ |
| public final class XPathEvaluatorImpl implements XPathEvaluator { |
| |
| /** |
| * This prefix resolver is created whenever null is passed to the |
| * evaluate method. Its purpose is to satisfy the DOM L3 XPath API |
| * requirement that if a null prefix resolver is used, an exception |
| * should only be thrown when an attempt is made to resolve a prefix. |
| */ |
| private static class DummyPrefixResolver implements PrefixResolver { |
| |
| /** |
| * Constructor for DummyPrefixResolver. |
| */ |
| DummyPrefixResolver() {} |
| |
| /** |
| * @exception DOMException |
| * NAMESPACE_ERR: Always throws this exceptionn |
| * |
| * @see org.apache.xml.utils.PrefixResolver#getNamespaceForPrefix(String, Node) |
| */ |
| public String getNamespaceForPrefix(String prefix, Node context) { |
| String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NULL_RESOLVER, null); |
| throw new DOMException(DOMException.NAMESPACE_ERR, fmsg); // Unable to resolve prefix with null prefix resolver. |
| } |
| |
| /** |
| * @exception DOMException |
| * NAMESPACE_ERR: Always throws this exceptionn |
| * |
| * @see org.apache.xml.utils.PrefixResolver#getNamespaceForPrefix(String) |
| */ |
| public String getNamespaceForPrefix(String prefix) { |
| return getNamespaceForPrefix(prefix,null); |
| } |
| |
| /** |
| * @see org.apache.xml.utils.PrefixResolver#handlesNullPrefixes() |
| */ |
| public boolean handlesNullPrefixes() { |
| return false; |
| } |
| |
| /** |
| * @see org.apache.xml.utils.PrefixResolver#getBaseIdentifier() |
| */ |
| public String getBaseIdentifier() { |
| return null; |
| } |
| |
| } |
| |
| /** |
| * The document to be searched to parallel the case where the XPathEvaluator |
| * is obtained by casting a Document. |
| */ |
| private final Document m_doc; |
| |
| /** |
| * Constructor for XPathEvaluatorImpl. |
| * |
| * @param doc The document to be searched, to parallel the case where'' |
| * the XPathEvaluator is obtained by casting the document. |
| */ |
| public XPathEvaluatorImpl(Document doc) { |
| m_doc = doc; |
| } |
| |
| /** |
| * Constructor in the case that the XPath expression can be evaluated |
| * without needing an XML document at all. |
| * |
| */ |
| public XPathEvaluatorImpl() { |
| m_doc = null; |
| } |
| |
| /** |
| * Creates a parsed XPath expression with resolved namespaces. This is |
| * useful when an expression will be reused in an application since it |
| * makes it possible to compile the expression string into a more |
| * efficient internal form and preresolve all namespace prefixes which |
| * occur within the expression. |
| * |
| * @param expression The XPath expression string to be parsed. |
| * @param resolver The <code>resolver</code> permits translation of |
| * prefixes within the XPath expression into appropriate namespace URIs |
| * . If this is specified as <code>null</code>, any namespace prefix |
| * within the expression will result in <code>DOMException</code> |
| * being thrown with the code <code>NAMESPACE_ERR</code>. |
| * @return The compiled form of the XPath expression. |
| * @exception XPathException |
| * INVALID_EXPRESSION_ERR: Raised if the expression is not legal |
| * according to the rules of the <code>XPathEvaluator</code>i |
| * @exception DOMException |
| * NAMESPACE_ERR: Raised if the expression contains namespace prefixes |
| * which cannot be resolved by the specified |
| * <code>XPathNSResolver</code>. |
| * |
| * @see org.w3c.dom.xpath.XPathEvaluator#createExpression(String, XPathNSResolver) |
| */ |
| public XPathExpression createExpression( |
| String expression, |
| XPathNSResolver resolver) |
| throws XPathException, DOMException { |
| |
| try { |
| |
| // If the resolver is null, create a dummy prefix resolver |
| XPath xpath = new XPath(expression,null, |
| ((null == resolver) ? new DummyPrefixResolver() : ((PrefixResolver)resolver)), |
| XPath.SELECT); |
| |
| return new XPathExpressionImpl(xpath, m_doc); |
| |
| } catch (TransformerException e) { |
| // Need to pass back exception code DOMException.NAMESPACE_ERR also. |
| // Error found in DOM Level 3 XPath Test Suite. |
| if(e instanceof XPathStylesheetDOM3Exception) |
| throw new DOMException(DOMException.NAMESPACE_ERR,e.getMessageAndLocation()); |
| else |
| throw new XPathException(XPathException.INVALID_EXPRESSION_ERR,e.getMessageAndLocation()); |
| |
| } |
| } |
| |
| /** |
| * Adapts any DOM node to resolve namespaces so that an XPath expression |
| * can be easily evaluated relative to the context of the node where it |
| * appeared within the document. This adapter works like the DOM Level 3 |
| * method <code>lookupNamespaceURI</code> on nodes in resolving the |
| * namespaceURI from a given prefix using the current information available |
| * in the node's hierarchy at the time lookupNamespaceURI is called, also |
| * correctly resolving the implicit xml prefix. |
| * |
| * @param nodeResolver The node to be used as a context for namespace |
| * resolution. |
| * @return <code>XPathNSResolver</code> which resolves namespaces with |
| * respect to the definitions in scope for a specified node. |
| * |
| * @see org.w3c.dom.xpath.XPathEvaluator#createNSResolver(Node) |
| */ |
| public XPathNSResolver createNSResolver(Node nodeResolver) { |
| |
| return new XPathNSResolverImpl((nodeResolver.getNodeType() == Node.DOCUMENT_NODE) |
| ? ((Document) nodeResolver).getDocumentElement() : nodeResolver); |
| } |
| |
| /** |
| * Evaluates an XPath expression string and returns a result of the |
| * specified type if possible. |
| * |
| * @param expression The XPath expression string to be parsed and |
| * evaluated. |
| * @param contextNode The <code>context</code> is context node for the |
| * evaluation of this XPath expression. If the XPathEvaluator was |
| * obtained by casting the <code>Document</code> then this must be |
| * owned by the same document and must be a <code>Document</code>, |
| * <code>Element</code>, <code>Attribute</code>, <code>Text</code>, |
| * <code>CDATASection</code>, <code>Comment</code>, |
| * <code>ProcessingInstruction</code>, or <code>XPathNamespace</code> |
| * node. If the context node is a <code>Text</code> or a |
| * <code>CDATASection</code>, then the context is interpreted as the |
| * whole logical text node as seen by XPath, unless the node is empty |
| * in which case it may not serve as the XPath context. |
| * @param resolver The <code>resolver</code> permits translation of |
| * prefixes within the XPath expression into appropriate namespace URIs |
| * . If this is specified as <code>null</code>, any namespace prefix |
| * within the expression will result in <code>DOMException</code> |
| * being thrown with the code <code>NAMESPACE_ERR</code>. |
| * @param type If a specific <code>type</code> is specified, then the |
| * result will be coerced to return the specified type relying on |
| * XPath type conversions and fail if the desired coercion is not |
| * possible. This must be one of the type codes of |
| * <code>XPathResult</code>. |
| * @param result The <code>result</code> specifies a specific result |
| * object which may be reused and returned by this method. If this is |
| * specified as <code>null</code>or the implementation does not reuse |
| * the specified result, a new result object will be constructed and |
| * returned.For XPath 1.0 results, this object will be of type |
| * <code>XPathResult</code>. |
| * @return The result of the evaluation of the XPath expression.For XPath |
| * 1.0 results, this object will be of type <code>XPathResult</code>. |
| * @exception XPathException |
| * INVALID_EXPRESSION_ERR: Raised if the expression is not legal |
| * according to the rules of the <code>XPathEvaluator</code>i |
| * <br>TYPE_ERR: Raised if the result cannot be converted to return the |
| * specified type. |
| * @exception DOMException |
| * NAMESPACE_ERR: Raised if the expression contains namespace prefixes |
| * which cannot be resolved by the specified |
| * <code>XPathNSResolver</code>. |
| * <br>WRONG_DOCUMENT_ERR: The Node is from a document that is not |
| * supported by this XPathEvaluator. |
| * <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath |
| * context node. |
| * |
| * @see org.w3c.dom.xpath.XPathEvaluator#evaluate(String, Node, XPathNSResolver, short, XPathResult) |
| */ |
| public Object evaluate( |
| String expression, |
| Node contextNode, |
| XPathNSResolver resolver, |
| short type, |
| Object result) |
| throws XPathException, DOMException { |
| |
| XPathExpression xpathExpression = createExpression(expression, resolver); |
| |
| return xpathExpression.evaluate(contextNode, type, result); |
| } |
| |
| } |