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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// $Id: XPath.java 569998 2007-08-27 04:40:02Z mrglavas $
package javax.xml.xpath;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import org.xml.sax.InputSource;
/**
* XPath provides access to the XPath evaluation environment and expressions.
*
*
*
*
* Evaluation of XPath Expressions.
*
*
*
*
* context
*
* If a request is made to evaluate the expression in the absence
* of a context item, an empty document node will be used for the context.
* For the purposes of evaluating XPath expressions, a DocumentFragment
* is treated like a Document node.
*
*
*
* variables
*
* 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.
*
*
*
* functions
*
* 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 null for the function.
*
*
*
* QNames
*
* QNames in the expression are resolved against the XPath namespace context
* set with {@link #setNamespaceContext(NamespaceContext nsContext)}.
*
*
*
* result
*
* 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.
*
*
*
*
* @author Norman Walsh
* @author Jeff Suttor
* @version $Revision: 569998 $, $Date: 2007-08-26 21:40:02 -0700 (Sun, 26 Aug 2007) $
* @see XML Path Language (XPath) Version 1.0
* @since 1.5
*/
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.
*/
public void reset();
/**
* Establish a variable resolver.
*
* A NullPointerException is thrown if resolver is null.
*
* @param resolver Variable resolver.
*
* @throws NullPointerException If resolver is null.
*/
public void setXPathVariableResolver(XPathVariableResolver resolver);
/**
* Return the current variable resolver.
*
* null is returned in no variable resolver is in effect.
*
* @return Current variable resolver.
*/
public XPathVariableResolver getXPathVariableResolver();
/**
* Establish a function resolver.
*
* A NullPointerException is thrown if resolver is null.
*
* @param resolver XPath function resolver.
*
* @throws NullPointerException If resolver is null.
*/
public void setXPathFunctionResolver(XPathFunctionResolver resolver);
/**
* Return the current function resolver.
*
* null is returned in no function resolver is in effect.
*
* @return Current function resolver.
*/
public XPathFunctionResolver getXPathFunctionResolver();
/**
* Establish a namespace context.
*
* A NullPointerException is thrown if nsContext is null.
*
* @param nsContext Namespace context to use.
*
* @throws NullPointerException If nsContext is null.
*/
public void setNamespaceContext(NamespaceContext nsContext);
/**
* Return the current namespace context.
*
* null is returned in no namespace context is in effect.
*
* @return Current Namespace context.
*/
public NamespaceContext getNamespaceContext();
/**
* Compile an XPath expression for later evaluation.
*
* If 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 resolved with the XPathFunctionResolver.
*
* If expression is null, a NullPointerException is thrown.
*
* @param expression The XPath expression.
*
* @return Compiled XPath expression.
* @throws XPathExpressionException If expression cannot be compiled.
* @throws NullPointerException If expression is 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.
*
* 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.
*
* @param expression The XPath expression.
* @param item The starting context (node or node list, for example).
* @param returnType The desired return type.
*
* @return Result of evaluating an XPath expression as an Object of 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.
*/
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}.
*
* See Evaluation of XPath Expressions for context item evaluation,
* 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.
*
* @param expression The XPath expression.
* @param item The starting context (node or node list, for example).
*
* @return The String that is the result of evaluating the expression and
* converting the result to a String.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws NullPointerException If expression is 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.
*
* See Evaluation of XPath Expressions for context item evaluation,
* 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.
*
* @param expression The XPath expression.
* @param source The input source of the document to evaluate over.
* @param returnType The desired return type.
*
* @return The 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.
*/
public Object evaluate(
String expression,
InputSource source,
QName returnType)
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.
*
* If expression or source is null,
* then a NullPointerException is thrown.
*
* @param expression The XPath expression.
* @param source The 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.
*
* @throws XPathExpressionException If expression cannot be evaluated.
* @throws NullPointerException If expression or source is null.
*/
public String evaluate(String expression, InputSource source)
throws XPathExpressionException;
}