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package javax.xml.xpath;
import javax.xml.namespace.QName;
import org.xml.sax.InputSource;
/**
* {@code XPathExpression} provides access to compiled XPath expressions.
*
* <a name="XPathExpression-evaluation"></a>
* <table border="1" cellpadding="2">
* <thead>
* <tr>
* <th colspan="2">Evaluation of XPath Expressions.</th>
* </tr>
* </thead>
* <tr>
* <td>context</td>
* <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>
* <td>variables</td>
* <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>
* <td>functions</td>
* <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>
* <td>QNames</td>
* <td>
* QNames in the expression are resolved against the XPath namespace context.
* </td>
* </tr>
* <tr>
* <td>result</td>
* <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 <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a>
* @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
* @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);
}
}