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320 lines
13 KiB
320 lines
13 KiB
/*
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* Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.xml.xpath;
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import org.xml.sax.InputSource;
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import javax.xml.namespace.QName;
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import javax.xml.namespace.NamespaceContext;
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/**
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* <p><code>XPath</code> provides access to the XPath evaluation environment and expressions.</p>
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*
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* <a name="XPath-evaluation"/>
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* <table 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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* set with {@link #setXPathVariableResolver(XPathVariableResolver resolver)}.
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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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* set with {@link #setXPathFunctionResolver(XPathFunctionResolver resolver)}.
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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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* set with {@link #setNamespaceContext(NamespaceContext nsContext)}.
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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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* <p>An XPath object is not thread-safe and not reentrant.
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* In other words, it is the application's responsibility to make
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* sure that one {@link XPath} object is not used from
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* more than one thread at any given time, and while the <code>evaluate</code>
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* method is invoked, applications may not recursively call
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* the <code>evaluate</code> method.
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* <p>
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*
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* @author <a href="Norman.Walsh@Sun.com">Norman Walsh</a>
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* @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>
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* @see <a href="http://www.w3.org/TR/xpath">XML Path Language (XPath) Version 1.0</a>
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* @since 1.5
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*/
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public interface XPath {
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/**
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* <p>Reset this <code>XPath</code> to its original configuration.</p>
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*
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* <p><code>XPath</code> is reset to the same state as when it was created with
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* {@link XPathFactory#newXPath()}.
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* <code>reset()</code> is designed to allow the reuse of existing <code>XPath</code>s
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* thus saving resources associated with the creation of new <code>XPath</code>s.</p>
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*
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* <p>The reset <code>XPath</code> is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
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* or {@link NamespaceContext} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.
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* It is guaranteed to have a functionally equal <code>XPathFunctionResolver</code>, <code>XPathVariableResolver</code>
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* and <code>NamespaceContext</code>.</p>
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*/
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public void reset();
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/**
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* <p>Establish a variable resolver.</p>
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*
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* <p>A <code>NullPointerException</code> is thrown if <code>resolver</code> is <code>null</code>.</p>
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*
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* @param resolver Variable resolver.
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*
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* @throws NullPointerException If <code>resolver</code> is <code>null</code>.
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*/
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public void setXPathVariableResolver(XPathVariableResolver resolver);
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/**
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* <p>Return the current variable resolver.</p>
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*
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* <p><code>null</code> is returned in no variable resolver is in effect.</p>
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*
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* @return Current variable resolver.
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*/
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public XPathVariableResolver getXPathVariableResolver();
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/**
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* <p>Establish a function resolver.</p>
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*
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* <p>A <code>NullPointerException</code> is thrown if <code>resolver</code> is <code>null</code>.</p>
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*
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* @param resolver XPath function resolver.
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*
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* @throws NullPointerException If <code>resolver</code> is <code>null</code>.
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*/
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public void setXPathFunctionResolver(XPathFunctionResolver resolver);
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/**
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* <p>Return the current function resolver.</p>
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*
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* <p><code>null</code> is returned in no function resolver is in effect.</p>
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*
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* @return Current function resolver.
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*/
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public XPathFunctionResolver getXPathFunctionResolver();
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/**
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* <p>Establish a namespace context.</p>
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*
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* <p>A <code>NullPointerException</code> is thrown if <code>nsContext</code> is <code>null</code>.</p>
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*
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* @param nsContext Namespace context to use.
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*
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* @throws NullPointerException If <code>nsContext</code> is <code>null</code>.
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*/
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public void setNamespaceContext(NamespaceContext nsContext);
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/**
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* <p>Return the current namespace context.</p>
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*
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* <p><code>null</code> is returned in no namespace context is in effect.</p>
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*
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* @return Current Namespace context.
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*/
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public NamespaceContext getNamespaceContext();
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/**
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* <p>Compile an XPath expression for later evaluation.</p>
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*
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* <p>If <code>expression</code> contains any {@link XPathFunction}s,
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* they must be available via the {@link XPathFunctionResolver}.
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* An {@link XPathExpressionException} will be thrown if the
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* <code>XPathFunction</code>
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* cannot be resovled with the <code>XPathFunctionResolver</code>.</p>
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*
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* <p>If <code>expression</code> contains any variables, the
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* {@link XPathVariableResolver} in effect
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* <strong>at compile time</strong> will be used to resolve them.</p>
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*
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* <p>If <code>expression</code> is <code>null</code>, a <code>NullPointerException</code> is thrown.</p>
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*
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* @param expression The XPath expression.
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*
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* @return Compiled XPath expression.
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* @throws XPathExpressionException If <code>expression</code> cannot be compiled.
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* @throws NullPointerException If <code>expression</code> is <code>null</code>.
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*/
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public XPathExpression compile(String expression)
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throws XPathExpressionException;
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/**
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* <p>Evaluate an <code>XPath</code> 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="#XPath-evaluation">Evaluation of XPath Expressions</a> for context item evaluation,
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* variable, function and <code>QName</code> 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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* {@link XPathConstants#NUMBER NUMBER},
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* {@link XPathConstants#STRING STRING},
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* {@link XPathConstants#BOOLEAN BOOLEAN},
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* {@link XPathConstants#NODE NODE} or
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* {@link XPathConstants#NODESET NODESET})
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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>expression</code> or <code>returnType</code> is <code>null</code>, then a
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* <code>NullPointerException</code> is thrown.</p>
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*
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* @param expression The XPath expression.
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* @param item The starting context (a node, for example).
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* @param returnType The desired return type.
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*
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* @return Result of evaluating an XPath expression as an <code>Object</code> of <code>returnType</code>.
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*
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* @throws XPathExpressionException If <code>expression</code> 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>expression</code> or <code>returnType</code> is <code>null</code>.
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*/
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public Object evaluate(String expression, Object item, QName returnType)
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throws XPathExpressionException;
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/**
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* <p>Evaluate an 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(String expression, 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="#XPath-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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* If <code>expression</code> is <code>null</code>, then a <code>NullPointerException</code> is thrown.</p>
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*
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* @param expression The XPath expression.
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* @param item The starting context (a node, for example).
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*
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* @return The <code>String</code> that is the result of evaluating the expression and
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* converting the result to a <code>String</code>.
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*
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* @throws XPathExpressionException If <code>expression</code> cannot be evaluated.
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* @throws NullPointerException If <code>expression</code> is <code>null</code>.
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*/
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public String evaluate(String expression, Object item)
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throws XPathExpressionException;
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/**
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* <p>Evaluate an XPath expression in the context of the specified <code>InputSource</code>
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* and return the result as the 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(String expression, Object item, QName returnType)} on the resulting document object.</p>
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*
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* <p>See <a href="#XPath-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>expression</code>, <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 expression The XPath expression.
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* @param source The input source 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 encapsulates the result of evaluating the expression.
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*
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* @throws XPathExpressionException If 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>expression</code>, <code>source</code> or <code>returnType</code>
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* is <code>null</code>.
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*/
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public Object evaluate(
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String expression,
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InputSource source,
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QName returnType)
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throws XPathExpressionException;
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/**
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* <p>Evaluate an XPath expression in the context of the specified <code>InputSource</code>
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* and return the result as a <code>String</code>.</p>
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*
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* <p>This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
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* <code>returnType</code> of {@link XPathConstants#STRING}.</p>
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*
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* <p>See <a href="#XPath-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>expression</code> or <code>source</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 expression The XPath expression.
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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
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* converting the result to a <code>String</code>.
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*
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* @throws XPathExpressionException If expression cannot be evaluated.
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* @throws NullPointerException If <code>expression</code> or <code>source</code> is <code>null</code>.
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*/
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public String evaluate(String expression, InputSource source)
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throws XPathExpressionException;
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}
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