186 lines
8.4 KiB
Java
186 lines
8.4 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// $Id: XPathExpression.java 446598 2006-09-15 12:55:40Z jeremias $
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package javax.xml.xpath;
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import javax.xml.namespace.QName;
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import org.xml.sax.InputSource;
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/**
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* <p><code>XPathExpression</code> provides access to compiled XPath expressions.</p>
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*
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* <table id="XPathExpression-evaluation" border="1" cellpadding="2">
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* <thead>
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* <tr>
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* <th colspan="2">Evaluation of XPath Expressions.</th>
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* </tr>
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* </thead>
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* <tbody>
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* <tr>
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* <td>context</td>
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* <td>
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* If a request is made to evaluate the expression in the absence
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* of a context item, an empty document node will be used for the context.
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* For the purposes of evaluating XPath expressions, a DocumentFragment
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* is treated like a Document node.
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* </td>
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* </tr>
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* <tr>
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* <td>variables</td>
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* <td>
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* If the expression contains a variable reference, its value will be found through the {@link XPathVariableResolver}.
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* An {@link XPathExpressionException} is raised if the variable resolver is undefined or
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* the resolver returns <code>null</code> for the variable.
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* The value of a variable must be immutable through the course of any single evaluation.</p>
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* </td>
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* </tr>
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* <tr>
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* <td>functions</td>
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* <td>
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* If the expression contains a function reference, the function will be found through the {@link XPathFunctionResolver}.
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* An {@link XPathExpressionException} is raised if the function resolver is undefined or
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* the function resolver returns <code>null</code> for the function.</p>
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* </td>
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* </tr>
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* <tr>
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* <td>QNames</td>
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* <td>
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* QNames in the expression are resolved against the XPath namespace context.
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* </td>
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* </tr>
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* <tr>
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* <td>result</td>
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* <td>
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* This result of evaluating an expression is converted to an instance of the desired return type.
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* Valid return types are defined in {@link XPathConstants}.
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* Conversion to the return type follows XPath conversion rules.</p>
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* </td>
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* </tr>
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* </table>
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*
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* @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
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* @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
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* @version $Revision: 446598 $, $Date: 2006-09-15 05:55:40 -0700 (Fri, 15 Sep 2006) $
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* @see <a href="http://www.w3.org/TR/xpath#section-Expressions">XML Path Language (XPath) Version 1.0, Expressions</a>
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* @since 1.5
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*/
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public interface XPathExpression {
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/**
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* <p>Evaluate the compiled XPath expression in the specified context and return the result as the specified type.</p>
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*
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* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
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* variable, function and QName resolution and return type conversion.</p>
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*
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* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants},
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* then an <code>IllegalArgumentException</code> is thrown.</p>
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*
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* <p>If a <code>null</code> value is provided for
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* <code>item</code>, an empty document will be used for the
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* context.
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* If <code>returnType</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
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*
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* @param item The starting context (node or node list, for example).
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* @param returnType The desired return type.
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*
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* @return The <code>Object</code> that is the result of evaluating the expression and converting the result to
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* <code>returnType</code>.
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*
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* @throws XPathExpressionException If the expression cannot be evaluated.
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* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
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* @throws NullPointerException If <code>returnType</code> is <code>null</code>.
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*/
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public Object evaluate(Object item, QName returnType)
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throws XPathExpressionException;
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/**
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* <p>Evaluate the compiled XPath expression in the specified context and return the result as a <code>String</code>.</p>
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*
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* <p>This method calls {@link #evaluate(Object item, QName returnType)} with a <code>returnType</code> of
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* {@link XPathConstants#STRING}.</p>
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*
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* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
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* variable, function and QName resolution and return type conversion.</p>
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*
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* <p>If a <code>null</code> value is provided for
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* <code>item</code>, an empty document will be used for the
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* context.
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*
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* @param item The starting context (node or node list, for example).
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*
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* @return The <code>String</code> that is the result of evaluating the expression and converting the result to a
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* <code>String</code>.
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*
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* @throws XPathExpressionException If the expression cannot be evaluated.
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*/
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public String evaluate(Object item)
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throws XPathExpressionException;
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/**
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* <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as the
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* specified type.</p>
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*
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* <p>This method builds a data model for the {@link InputSource} and calls
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* {@link #evaluate(Object item, QName returnType)} on the resulting document object.</p>
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*
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* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
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* variable, function and QName resolution and return type conversion.</p>
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*
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* <p>If <code>returnType</code> is not one of the types defined in {@link XPathConstants},
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* then an <code>IllegalArgumentException</code> is thrown.</p>
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*
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* <p>If <code>source</code> or <code>returnType</code> is <code>null</code>,
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* then a <code>NullPointerException</code> is thrown.</p>
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*
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* @param source The <code>InputSource</code> of the document to evaluate over.
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* @param returnType The desired return type.
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*
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* @return The <code>Object</code> that is the result of evaluating the expression and converting the result to
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* <code>returnType</code>.
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*
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* @throws XPathExpressionException If the expression cannot be evaluated.
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* @throws IllegalArgumentException If <code>returnType</code> is not one of the types defined in {@link XPathConstants}.
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* @throws NullPointerException If <code>source</code> or <code>returnType</code> is <code>null</code>.
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*/
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public Object evaluate(InputSource source, QName returnType)
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throws XPathExpressionException;
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/**
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* <p>Evaluate the compiled XPath expression in the context of the specified <code>InputSource</code> and return the result as a
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* <code>String</code>.</p>
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*
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* <p>This method calls {@link #evaluate(InputSource source, QName returnType)} with a <code>returnType</code> of
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* {@link XPathConstants#STRING}.</p>
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*
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* <p>See <a href="#XPathExpression-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
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* variable, function and QName resolution and return type conversion.</p>
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*
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* <p>If <code>source</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
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*
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* @param source The <code>InputSource</code> of the document to evaluate over.
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*
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* @return The <code>String</code> that is the result of evaluating the expression and converting the result to a
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* <code>String</code>.
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*
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* @throws XPathExpressionException If the expression cannot be evaluated.
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* @throws NullPointerException If <code>source</code> is <code>null</code>.
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*/
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public String evaluate(InputSource source)
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throws XPathExpressionException;
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}
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