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/* * The contents of this file are subject to the terms * of the Common Development and Distribution License * (the "License"). You may not use this file except * in compliance with the License. * * You can obtain a copy of the license at * https://jaxp.dev.java.net/CDDLv1.0.html. * See the License for the specific language governing * permissions and limitations under the License. * * When distributing Covered Code, include this CDDL * HEADER in each file and include the License file at * https://jaxp.dev.java.net/CDDLv1.0.html * If applicable add the following below this CDDL HEADER * with the fields enclosed by brackets "[]" replaced with * your own identifying information: Portions Copyright * [year] [name of copyright owner] */ /* * $Id: XMLEntityReader.java,v 1.3 2005/11/03 17:02:21 jeffsuttor Exp $ * @(#)XPathExpression.java 1.15 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved. */ package javax.xml.xpath; import org.xml.sax.InputSource; import javax.xml.namespace.QName; /** * <p><code>XPathExpression</code> provides access to compiled XPath expressions.</p> * * <a name="XPathExpression-evaluation"/> * <table border="1" cellpadding="2"> * <thead> * <tr> * <th colspan="2">Evaluation of XPath Expressions.</th> * </tr> * </thead> * <tbody> * <tr> * <td>context</td> * <td> * If a request is made to evaluate the expression in the absence * of a context item, an empty document node will be used for the context. * For the purposes of evaluating XPath expressions, a DocumentFragment * is treated like a Document node. * </td> * </tr> * <tr> * <td>variables</td> * <td> * If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}. * An {@link XPathExpressionException} is raised if the variable resolver is undefined or * the resolver returns <code>null</code> for the variable. * The value of a variable must be immutable through the course of any single evaluation.</p> * </td> * </tr> * <tr> * <td>functions</td> * <td> * If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}. * An {@link XPathExpressionException} is raised if the function resolver is undefined or * the function resolver returns <code>null</code> for the function.</p> * </td> * </tr> * <tr> * <td>QNames</td> * <td> * QNames in the expression are resolved against the XPath namespace context. * </td> * </tr> * <tr> * <td>result</td> * <td> * This result of evaluating an expression is converted to an instance of the desired return type. * Valid return types are defined in {@link XPathConstants}. * Conversion to the return type follows XPath conversion rules.</p> * </td> * </tr> * </table> * * <p>An XPath expression is not thread-safe and not reentrant. * In other words, it is the application's responsibility to make * sure that one {@link XPathExpression} object is not used from * more than one thread at any given time, and while the <code>evaluate</code> * method is invoked, applications may not recursively call * the <code>evaluate</code> method. * <p> * * @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a> * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a> * @version $Revision: 1.4 $, $Date: 2005/10/13 17:00:49 $ * @see <a href="http://www.w3.org/TR/xpath#section-Expressions">XML Path Language (XPath) Version 1.0, Expressions</a> * @since 1.5 */ public interface XPathExpression { /** * <p>Evaluate the compiled XPath expression in the specified context and return the result as the specified type.</p> * * <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion.</p> * * <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants}, * then an <code>IllegalArgumentException</code> is thrown.</p> * * <p>If a <code>null</code> value is provided for * <code>item</code>, an empty document will be used for the * context. * If <code>returnType</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p> * * @param item The starting context (a node, for example). * @param returnType The desired return type. * * @return The <code>Object</code> that is the result of evaluating the expression and converting the result to * <code>returnType</code>. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}. * @throws NullPointerException If <code>returnType</code> is <code>null</code>. */ public Object evaluate(Object item, QName returnType) throws XPathExpressionException; /** * <p>Evaluate the compiled XPath expression in the specified context and return the result as a <code>String</code>.</p> * * <p>This method calls {@link #evaluate(Object item, QName returnType)} with a <code>returnType</code> of * {@link XPathConstants#STRING}.</p> * * <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion.</p> * * <p>If a <code>null</code> value is provided for * <code>item</code>, an empty document will be used for the * context. * * @param item The starting context (a node, for example). * * @return The <code>String</code> that is the result of evaluating the expression and converting the result to a * <code>String</code>. * * @throws XPathExpressionException If the expression cannot be evaluated. */ public String evaluate(Object item) throws XPathExpressionException; /** * <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as the * specified type.</p> * * <p>This method builds a data model for the {@link InputSource} and calls * {@link #evaluate(Object item, QName returnType)} on the resulting document object.</p> * * <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion.</p> * * <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants}, * then an <code>IllegalArgumentException</code> is thrown.</p> * * <p>If <code>source</code> or <code>returnType</code> is <code>null</code>, * then a <code>NullPointerException</code> is thrown.</p> * * @param source The <code>InputSource</code> of the document to evaluate over. * @param returnType The desired return type. * * @return The <code>Object</code> that is the result of evaluating the expression and converting the result to * <code>returnType</code>. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}. * @throws NullPointerException If <code>source</code> or <code>returnType</code> is <code>null</code>. */ public Object evaluate(InputSource source, QName returnType) throws XPathExpressionException; /** * <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as a * <code>String</code>.</p> * * <p>This method calls {@link #evaluate(InputSource source, QName returnType)} with a <code>returnType</code> of * {@link XPathConstants#STRING}.</p> * * <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion.</p> * * <p>If <code>source</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p> * * @param source The <code>InputSource</code> of the document to evaluate over. * * @return The <code>String</code> that is the result of evaluating the expression and converting the result to a * <code>String</code>. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws NullPointerException If <code>source</code> is <code>null</code>. */ public String evaluate(InputSource source) throws XPathExpressionException; }