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	/*
	* Copyright (c) 2003, 2021, 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,
	* must be one of the types described in section
	* <a href="package-summary.html#XPath.Datatypes.Class">3.2 Class types</a>
	* in the package summary.
	*
	*
	* @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,
	* must be one of the types described in section
	* <a href="package-summary.html#XPath.Datatypes.Class">3.2 Class types</a>
	* in the package summary.
	*
	* @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);
	}
	}

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