XPath provides access to the XPath evaluation environment and expressions.
| Evaluation of XPath Expressions. | * * - * *|
|---|---|
| context | *
@@ -55,8 +54,8 @@
* 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 null for the variable.
- * The value of a variable must be immutable through the course of any single evaluation.
+ * the resolver returns {@code null} for the variable.
+ * The value of a variable must be immutable through the course of any single evaluation.
* |
*
| * 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. + * Conversion to the return type follows XPath conversion rules. * | *
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 evaluate
+ * more than one thread at any given time, and while the {@code evaluate}
* method is invoked, applications may not recursively call
- * the evaluate method.
+ * the {@code evaluate} method.
*
* * @author Norman Walsh @@ -100,36 +99,37 @@ */ public interface XPath { - /** - *
Reset this XPath to its original configuration.
XPath is reset to the same state as when it was created with
- * {@link XPathFactory#newXPath()}.
- * reset() is designed to allow the reuse of existing XPaths
- * thus saving resources associated with the creation of new XPaths.
The reset XPath is not guaranteed to have the same {@link XPathFunctionResolver}, {@link XPathVariableResolver}
- * or {@link NamespaceContext} Objects, e.g. {@link Object#equals(Object obj)}.
- * It is guaranteed to have a functionally equal XPathFunctionResolver, XPathVariableResolver
- * and NamespaceContext.
{@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. + * + *
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.
+ * Establish a variable resolver. * - *A NullPointerException is thrown if resolver is null.
A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
*
* @param resolver Variable resolver.
*
- * @throws NullPointerException If resolver is null.
+ * @throws NullPointerException If {@code resolver} is {@code null}.
*/
public void setXPathVariableResolver(XPathVariableResolver resolver);
/**
- *
Return the current variable resolver.
+ * Return the current variable resolver. * - *null is returned in no variable resolver is in effect.
{@code null} is returned in no variable resolver is in effect. * * @return Current variable resolver. */ @@ -136,40 +136,40 @@ public XPathVariableResolver getXPathVariableResolver(); /** - *
Establish a function resolver.
+ * Establish a function resolver. * - *A NullPointerException is thrown if resolver is null.
A {@code NullPointerException} is thrown if {@code resolver} is {@code null}.
*
* @param resolver XPath function resolver.
*
- * @throws NullPointerException If resolver is null.
+ * @throws NullPointerException If {@code resolver} is {@code null}.
*/
public void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
- *
Return the current function resolver.
+ * Return the current function resolver. + *+ * {@code null} is returned in no function resolver is in effect. * - *
null is returned in no function resolver is in effect.
Establish a namespace context.
+ * Establish a namespace context. * - *A NullPointerException is thrown if nsContext is null.
A {@code NullPointerException} is thrown if {@code nsContext} is {@code null}.
*
* @param nsContext Namespace context to use.
*
- * @throws NullPointerException If nsContext is null.
+ * @throws NullPointerException If {@code nsContext} is {@code null}.
*/
public void setNamespaceContext(NamespaceContext nsContext);
/**
- *
Return the current namespace context.
+ * Return the current namespace context. * - *null is returned in no namespace context is in effect.
{@code null} is returned in no namespace context is in effect. * * @return Current Namespace context. */ @@ -176,115 +176,111 @@ public NamespaceContext getNamespaceContext(); /** - *
Compile an XPath expression for later evaluation.
+ * Compile an XPath expression for later evaluation. * - *If expression contains any {@link XPathFunction}s,
+ *
If {@code expression} contains any {@link XPathFunction}s,
* they must be available via the {@link XPathFunctionResolver}.
* An {@link XPathExpressionException} will be thrown if the
- * XPathFunction
- * cannot be resovled with the XPathFunctionResolver.
If expression contains any variables, the
+ *
If {@code expression} contains any variables, the * {@link XPathVariableResolver} in effect - * at compile time will be used to resolve them.
+ * at compile time will be used to resolve them. * - *If expression is null, a NullPointerException is thrown.
expression cannot be compiled.
- * @throws NullPointerException If expression is null.
+ * @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 XPath expression in the specified context and return the result as the specified type.
See Evaluation of XPath Expressions for context item evaluation,
- * variable, function and QName resolution and return type conversion.
+ * See Evaluation of XPath Expressions + * for context item evaluation, variable, function and {@code QName} resolution + * and return type conversion. + *
+ * 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. * - *
If 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})
- * then an IllegalArgumentException is thrown.
If a null value is provided for
- * item, an empty document will be used for the
- * context.
- * If expression or returnType is null, then a
- * NullPointerException is thrown.
Object of returnType.
+ * @return The result of evaluating an XPath expression as an {@code Object} of {@code returnType}.
*
- * @throws XPathExpressionException If expression cannot be evaluated.
- * @throws IllegalArgumentException If returnType is not one of the types defined in {@link XPathConstants}.
- * @throws NullPointerException If expression or returnType is null.
+ * @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 String.
This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a returnType of
- * {@link XPathConstants#STRING}.
This method calls {@link #evaluate(String expression, Object item, QName returnType)} with a {@code returnType} of + * {@link XPathConstants#STRING}. * *
See Evaluation of XPath Expressions for context item evaluation, - * variable, function and QName resolution and return type conversion.
+ * variable, function and QName resolution and return type conversion. * - *If a null value is provided for
- * item, an empty document will be used for the
- * context.
- * If expression is null, then a NullPointerException is thrown.
+ * 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 starting context (a node, for example).
+ * @param item The context the XPath expression will be evaluated in.
*
- * @return The String that is the result of evaluating the expression and
- * converting the result to a String.
+ * @return The result of evaluating an XPath expression as a {@code String}.
*
- * @throws XPathExpressionException If expression cannot be evaluated.
- * @throws NullPointerException If expression is null.
+ * @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 InputSource
- * and return the result as the specified type.
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.
+ * {@link #evaluate(String expression, Object item, QName returnType)} on the resulting document object. * *See Evaluation of XPath Expressions for context item evaluation, - * variable, function and QName resolution and return type conversion.
+ * variable, function and QName resolution and return type conversion. * - *If returnType is not one of the types defined in {@link XPathConstants},
- * then an IllegalArgumentException is thrown.
If expression, source or returnType is null,
- * then a NullPointerException is thrown.
Object that encapsulates the result of evaluating the expression.
+ * @return The {@code Object} that encapsulates the result of evaluating the expression.
*
* @throws XPathExpressionException If expression cannot be evaluated.
- * @throws IllegalArgumentException If returnType is not one of the types defined in {@link XPathConstants}.
- * @throws NullPointerException If expression, source or returnType
- * is null.
+ * @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,
@@ -293,27 +289,209 @@
throws XPathExpressionException;
/**
- * Evaluate an XPath expression in the context of the specified InputSource
- * and return the result as a String.
This method calls {@link #evaluate(String expression, InputSource source, QName returnType)} with a
- * returnType of {@link XPathConstants#STRING}.
See Evaluation of XPath Expressions for context item evaluation, - * variable, function and QName resolution and return type conversion.
+ * variable, function and QName resolution and return type conversion. * - *If expression or source is null,
- * then a NullPointerException is thrown.
InputSource of the document to evaluate over.
+ * @param source The {@code InputSource} of the document to evaluate over.
*
- * @return The String that is the result of evaluating the expression and
- * converting the result to a String.
+ * @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 expression or source is null.
+ * @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}
+ *
+ * + * 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: + *
{@code
+ * (T)evaluate(expression, item,
+ * XPathEvaluationResult.XPathResultType.getQNameType(type));
+ * }
+ *
+ * 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 {@code
+ * evaluateExpression(expression, item, XPathEvaluationResult.class);
+ * }
+ * + * 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: + *
{@code
+ * evaluateExpression(expression, item, XPathEvaluationResult.class);
+ * }
+ *
+ * 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 1.9
+ */
+ 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.
+ * + * 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: + *
{@code
+ (T)evaluate(expression, source,
+ XPathEvaluationResult.XPathResultType.getQNameType(type));
+ * }
+ *
+ * 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 {@code
+ * evaluateExpression(expression, item, XPathEvaluationResult.class);
+ * }
+ * + * + * @implSpec + * The default implementation in the XPath API is equivalent to: + *
{@code
+ * evaluateExpression(expression, source, XPathEvaluationResult.class);
+ * }
+ *
+ * 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 1.9
+ */
+ default XPathEvaluationResult evaluateExpression(String expression, InputSource source)
+ throws XPathExpressionException
+ {
+ return evaluateExpression(expression, source, XPathEvaluationResult.class);
+ }
}