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/* * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.xml.xpath; import javax.xml.namespace.QName; import org.xml.sax.InputSource; /** * {@code XPathExpression} provides access to compiled XPath expressions. * The XPath evaluation is affected by the factors described in the following table. * * <a id="XPathExpression-evaluation"></a> * <table class="striped"> * <caption>Evaluation of XPath Expressions</caption> * <thead> * <tr> * <th scope="col">Factor</th> * <th scope="col">Behavior</th> * </tr> * </thead> * <tbody> * <tr> * <th scope="row">context</th> * <td> * The type of the context is implementation-dependent. If the value is * null, the operation must have no dependency on the context, otherwise * an XPathExpressionException will be thrown. * * For the purposes of evaluating XPath expressions, a DocumentFragment * is treated like a Document node. * </td> * </tr> * <tr> * <th scope="row">variables</th> * <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} for the variable. * The value of a variable must be immutable through the course of any single evaluation. * </td> * </tr> * <tr> * <th scope="row">functions</th> * <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} for the function. * </td> * </tr> * <tr> * <th scope="row">QNames</th> * <td> * QNames in the expression are resolved against the XPath namespace context. * </td> * </tr> * <tr> * <th scope="row">result</th> * <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. * </td> * </tr> * </tbody> * </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} * method is invoked, applications may not recursively call * the {@code evaluate} method. * * @author Norman Walsh * @author Jeff Suttor * @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 { /** * Evaluate the compiled XPath expression in the specified context and return the result as the specified type. * * <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> * The parameter {@code item} represents the context the XPath expression * will be operated on. The type of the context is implementation-dependent. * If the value is {@code null}, the operation must have no dependency on * the context, otherwise an XPathExpressionException will be thrown. * * @implNote * The type of the context is usually {@link org.w3c.dom.Node}. * * @param item The context the XPath expression will be evaluated in. * @param returnType The result type expected to be returned by the XPath expression. * * @return The {@code Object} that is the result of evaluating the expression and converting the result to * {@code returnType}. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}. * @throws NullPointerException If {@code returnType} is {@code null}. */ public Object evaluate(Object item, QName returnType) throws XPathExpressionException; /** * Evaluate the compiled XPath expression in the specified context and return the result as a {@code String}. * * <p>This method calls {@link #evaluate(Object item, QName returnType)} with a {@code returnType} of * {@link XPathConstants#STRING}. * * <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> * The parameter {@code item} represents the context the XPath expression * will be operated on. The type of the context is implementation-dependent. * If the value is {@code null}, the operation must have no dependency on * the context, otherwise an XPathExpressionException will be thrown. * * @implNote * The type of the context is usually {@link org.w3c.dom.Node}. * * @param item The context the XPath expression will be evaluated in. * * @return The result of evaluating an XPath expression as a {@code String}. * * @throws XPathExpressionException If the expression cannot be evaluated. */ public String evaluate(Object item) throws XPathExpressionException; /** * Evaluate the compiled XPath expression in the context * of the specified {@code InputSource} and return the result as the * specified type. * * <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>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion. * * <p>If {@code returnType} is not one of the types defined in {@link XPathConstants}, * then an {@code IllegalArgumentException} is thrown. * * <p>If {@code source} or {@code returnType} is {@code null}, * then a {@code NullPointerException} is thrown. * * @param source The {@code InputSource} of the document to evaluate over. * @param returnType The desired return type. * * @return The {@code Object} that is the result of evaluating the expression and converting the result to * {@code returnType}. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}. * @throws NullPointerException If {@code source or returnType} is {@code null}. */ public Object evaluate(InputSource source, QName returnType) throws XPathExpressionException; /** * Evaluate the compiled XPath expression in the context * of the specified {@code InputSource} and return the result as a * {@code String}. * * <p>This method calls {@link #evaluate(InputSource source, QName returnType)} with a {@code returnType} of * {@link XPathConstants#STRING}. * * <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>If {@code source} is {@code null}, then a {@code NullPointerException} is thrown. * * @param source The {@code InputSource} of the document to evaluate over. * * @return The {@code String} that is the result of evaluating the expression and converting the result to a * {@code String}. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws NullPointerException If {@code source} is {@code null}. */ public String evaluate(InputSource source) throws XPathExpressionException; /** * Evaluate the compiled XPath expression in the specified context, and return * the result with the type specified through the {@code class type}. * * <p> * The parameter {@code item} represents the context the XPath expression * will be operated on. The type of the context is implementation-dependent. * If the value is {@code null}, the operation must have no dependency on * the context, otherwise an XPathExpressionException will be thrown. * * @implNote * The type of the context is usually {@link org.w3c.dom.Node}. * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code * (T)evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type)); * }</pre> * * Since the {@code evaluate} method does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying * XPathEvaluationResult as the type will result in IllegalArgumentException. * Any implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override * this method. * * @param <T> The class type that will be returned by the XPath expression. * @param item The context the XPath expression will be evaluated in. * @param type The class type expected to be returned by the XPath expression. * * @return The result of evaluating the expression. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If {@code type} is not of the types * corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType * XPathResultType}, or XPathEvaluationResult is specified as the type but an * implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type is not available. * @throws NullPointerException If {@code type} is {@code null}. * * @since 9 */ default <T> T evaluateExpression(Object item, Class<T> type) throws XPathExpressionException { return type.cast(evaluate(item, XPathEvaluationResult.XPathResultType.getQNameType(type))); } /** * Evaluate the compiled XPath expression in the specified context. This is * equivalent to calling {@link #evaluateExpression(Object item, Class type)} * with type {@link XPathEvaluationResult}: * <pre> {@code * evaluateExpression(item, XPathEvaluationResult.class); * }</pre> * <p> * The parameter {@code item} represents the context the XPath expression * will be operated on. The type of the context is implementation-dependent. * If the value is {@code null}, the operation must have no dependency on * the context, otherwise an XPathExpressionException will be thrown. * * @implNote * The type of the context is usually {@link org.w3c.dom.Node}. * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code * evaluateExpression(item, XPathEvaluationResult.class); * }</pre> * * Since the {@code evaluate} method does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} * type, the default implementation of this method will always throw an * IllegalArgumentException. Any implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore * override this method. * * @param item The context the XPath expression will be evaluated in. * * @return The result of evaluating the expression. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If the implementation of this method * does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type. * * @since 9 */ default XPathEvaluationResult<?> evaluateExpression(Object item) throws XPathExpressionException { return evaluateExpression(item, XPathEvaluationResult.class); } /** * Evaluate the compiled XPath expression in the specified context, * and return the result with the type specified through the {@code class type} * <p> * This method builds a data model for the {@link InputSource} and calls * {@link #evaluateExpression(Object item, Class type)} on the resulting * document object. * <P> * By default, the JDK's data model is {@link org.w3c.dom.Document}. * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code (T)evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type)); * }</pre> * * Since the {@code evaluate} method does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type, specifying * XPathEvaluationResult as the type will result in IllegalArgumentException. * Any implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must override * this method. * * @param <T> The class type that will be returned by the XPath expression. * @param source The {@code InputSource} of the document to evaluate over. * @param type The class type expected to be returned by the XPath expression. * * @return The result of evaluating the expression. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If {@code type} is not of the types * corresponding to the types defined in the {@link XPathEvaluationResult.XPathResultType * XPathResultType}, or XPathEvaluationResult is specified as the type but an * implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type * is not available. * @throws NullPointerException If {@code source or type} is {@code null}. * * @since 9 */ default <T> T evaluateExpression(InputSource source, Class<T> type) throws XPathExpressionException { return type.cast(evaluate(source, XPathEvaluationResult.XPathResultType.getQNameType(type))); } /** * Evaluate the compiled XPath expression in the specified context. This is * equivalent to calling {@link #evaluateExpression(InputSource source, Class type)} * with type {@link XPathEvaluationResult}: * <pre> {@code * evaluateExpression(source, XPathEvaluationResult.class); * }</pre> * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code * (XPathEvaluationResult)evaluateExpression(source, XPathEvaluationResult.class); * }</pre> * * Since the {@code evaluate} method does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} * type, the default implementation of this method will always throw an * IllegalArgumentException. Any implementation supporting the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type must therefore * override this method. * * @param source The {@code InputSource} of the document to evaluate over. * * @return The result of evaluating the expression. * * @throws XPathExpressionException If the expression cannot be evaluated. * @throws IllegalArgumentException If the implementation of this method * does not support the * {@link XPathEvaluationResult.XPathResultType#ANY ANY} type. * @throws NullPointerException If {@code source} is {@code null}. * * @since 9 */ default XPathEvaluationResult<?> evaluateExpression(InputSource source) throws XPathExpressionException { return evaluateExpression(source, XPathEvaluationResult.class); } }