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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.NamespaceContext; import javax.xml.namespace.QName; import org.xml.sax.InputSource; /** * {@code XPath} provides access to the XPath evaluation environment and expressions. * The XPath evaluation is affected by the factors described in the following table. * * <a id="XPath-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} * set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}. * 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} * set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}. * 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 * set with {@link #setNamespaceContext(NamespaceContext nsContext)}. * </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 object is not thread-safe and not reentrant. * In other words, it is the application's responsibility to make * sure that one {@link XPath} 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">XML Path Language (XPath) Version 1.0</a> * @since 1.5 */ public interface XPath { /** * Reset this {@code XPath} to its original configuration. * * <p>{@code XPath} is reset to the same state as when it was created with * {@link XPathFactory#newXPath()}. * {@code reset()} is designed to allow the reuse of existing {@code XPath}s * thus saving resources associated with the creation of new {@code XPath}s. * * <p>The reset {@code XPath} is not guaranteed to have the same * {@link XPathFunctionResolver}, {@link XPathVariableResolver} * or {@link NamespaceContext} {@code Object}s, e.g. {@link Object#equals(Object obj)}. * It is guaranteed to have a functionally equal {@code XPathFunctionResolver}, * {@code XPathVariableResolver} and {@code NamespaceContext}. */ public void reset(); /** * Establish a variable resolver. * * <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}. * * @param resolver Variable resolver. * * @throws NullPointerException If {@code resolver} is {@code null}. */ public void setXPathVariableResolver(XPathVariableResolver resolver); /** * Return the current variable resolver. * * <p>{@code null} is returned in no variable resolver is in effect. * * @return Current variable resolver. */ public XPathVariableResolver getXPathVariableResolver(); /** * Establish a function resolver. * * <p>A {@code NullPointerException} is thrown if {@code resolver} is {@code null}. * * @param resolver XPath function resolver. * * @throws NullPointerException If {@code resolver} is {@code null}. */ public void setXPathFunctionResolver(XPathFunctionResolver resolver); /** * Return the current function resolver. * <p> * {@code null} is returned in no function resolver is in effect. * * @return Current function resolver. */ public XPathFunctionResolver getXPathFunctionResolver(); /** * Establish a namespace context. * * <p>A {@code NullPointerException} is thrown if {@code nsContext} is {@code null}. * * @param nsContext Namespace context to use. * * @throws NullPointerException If {@code nsContext} is {@code null}. */ public void setNamespaceContext(NamespaceContext nsContext); /** * Return the current namespace context. * * <p>{@code null} is returned in no namespace context is in effect. * * @return Current Namespace context. */ public NamespaceContext getNamespaceContext(); /** * Compile an XPath expression for later evaluation. * * <p>If {@code expression} contains any {@link XPathFunction}s, * they must be available via the {@link XPathFunctionResolver}. * An {@link XPathExpressionException} will be thrown if the * {@code XPathFunction} * cannot be resovled with the {@code XPathFunctionResolver}. * * <p>If {@code expression} contains any variables, the * {@link XPathVariableResolver} in effect * <strong>at compile time</strong> will be used to resolve them. * * @param expression The XPath expression. * * @return Compiled XPath expression. * @throws XPathExpressionException If {@code expression} cannot be compiled. * @throws NullPointerException If {@code expression} is {@code null}. */ public XPathExpression compile(String expression) throws XPathExpressionException; /** * Evaluate an {@code XPath} expression in the specified context and * return the result as the specified type. * * <p> * See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> * for context item evaluation, variable, function and {@code 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 expression The XPath expression. * @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 result of evaluating an XPath expression as an {@code Object} of {@code returnType}. * * @throws XPathExpressionException If {@code expression} cannot be evaluated. * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants} ( * {@link XPathConstants#NUMBER NUMBER}, * {@link XPathConstants#STRING STRING}, * {@link XPathConstants#BOOLEAN BOOLEAN}, * {@link XPathConstants#NODE NODE} or * {@link XPathConstants#NODESET NODESET}). * @throws NullPointerException If {@code expression or returnType} is {@code null}. */ public Object evaluate(String expression, Object item, QName returnType) throws XPathExpressionException; /** * Evaluate an XPath expression in the specified context and return the result as a {@code String}. * * <p>This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a {@code returnType} of * {@link XPathConstants#STRING}. * * <p>See <a href="#XPath-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 expression The XPath expression. * @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 {@code expression} cannot be evaluated. * @throws NullPointerException If {@code expression} is {@code null}. */ public String evaluate(String expression, Object item) throws XPathExpressionException; /** * Evaluate an 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(String expression, Object item, QName returnType)} on the resulting document object. * * <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion. * * @param expression The XPath expression. * @param source The input source of the document to evaluate over. * @param returnType The desired return type. * * @return The {@code Object} that encapsulates the result of evaluating the expression. * * @throws XPathExpressionException If expression cannot be evaluated. * @throws IllegalArgumentException If {@code returnType} is not one of the types defined in {@link XPathConstants}. * @throws NullPointerException If {@code expression, source or returnType} is {@code null}. */ public Object evaluate(String expression, InputSource source, QName returnType) throws XPathExpressionException; /** * Evaluate an XPath expression in the context of the specified {@code InputSource} * and return the result as a {@code String}. * * <p>This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a * {@code returnType} of {@link XPathConstants#STRING}. * * <p>See <a href="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation, * variable, function and QName resolution and return type conversion. * * @param expression The XPath expression. * @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 expression cannot be evaluated. * @throws NullPointerException If {@code expression or source} is {@code null}. */ public String evaluate(String expression, InputSource source) throws XPathExpressionException; /** * Evaluate an 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(expression, 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 expression 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}, * 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 expression or type} is {@code null}. * * @since 9 */ default <T> T evaluateExpression(String expression, Object item, Class<T> type) throws XPathExpressionException { return type.cast(evaluate(expression, item, XPathEvaluationResult.XPathResultType.getQNameType(type))); } /** * Evaluate an XPath expression in the specified context. This is equivalent to * calling {@link #evaluateExpression(String expression, Object item, Class type)} * with type {@link XPathEvaluationResult}: * <pre> {@code * evaluateExpression(expression, 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(expression, 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 expression The XPath expression. * @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. * @throws NullPointerException If {@code expression} is {@code null}. * * @since 9 */ default XPathEvaluationResult<?> evaluateExpression(String expression, Object item) throws XPathExpressionException { return evaluateExpression(expression, item, XPathEvaluationResult.class); } /** * Evaluate an XPath expression in the context of the specified {@code source} * and return the result as specified. * <p> * This method builds a data model for the {@link InputSource} and calls * {@link #evaluateExpression(String expression, Object item, Class type)} * on the resulting document object. The data model is usually * {@link org.w3c.dom.Document} * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code (T)evaluate(expression, 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 expression The XPath expression. * @param source The input source 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 expression, source or type}is {@code null}. * * @since 9 */ default <T> T evaluateExpression(String expression, InputSource source, Class<T> type) throws XPathExpressionException { return type.cast(evaluate(expression, source, XPathEvaluationResult.XPathResultType.getQNameType(type))); } /** * Evaluate an XPath expression in the specified context. This is equivalent to * calling {@link #evaluateExpression(String expression, Object item, Class type)} * with type {@link XPathEvaluationResult}: * <pre> {@code * evaluateExpression(expression, item, XPathEvaluationResult.class); * }</pre> * * @implSpec * The default implementation in the XPath API is equivalent to: * <pre> {@code * evaluateExpression(expression, 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 expression The XPath expression. * @param source The input source 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 expression or source} is {@code null}. * * @since 9 */ default XPathEvaluationResult<?> evaluateExpression(String expression, InputSource source) throws XPathExpressionException { return evaluateExpression(expression, source, XPathEvaluationResult.class); } }