/*
* Copyright 1999,2004 The Apache Software Foundation.
*
* Licensed 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.
*/
package org.apache.taglibs.standard.lang.jpath.expression;
import javax.servlet.jsp.PageContext;
import org.apache.taglibs.standard.lang.jpath.adapter.ConversionException;
import org.apache.taglibs.standard.lang.jpath.adapter.Convert;
import org.apache.taglibs.standard.lang.jpath.adapter.IterationContext;
import org.apache.taglibs.standard.lang.jpath.adapter.JSPList;
import org.apache.taglibs.standard.lang.jpath.adapter.JSPListUnion;
/**
* The UnionOperator class
*
*
* @author <a href='mailto:scott.hasse@isthmusgroup.com'>Scott Hasse</a>
* @version
*/
public class UnionOperator extends SimpleNode {
/**
* Used to create an instance of the UnionOperator class
*
*
* @param id
*
*/
public UnionOperator(int id) {
super(id);
}
/**
* Used to create an instance of the UnionOperator class
*
*
* @param p
* @param id
*
*/
public UnionOperator(Parser p, int id) {
super(p, id);
}
/**
* Provides a method to print a normalized version of the original
* expression. The normalized version has standardized spacing and
* parenthesis, and can be used to compare expressions formatted
* in different ways to see if they are actually the same expression.
*
*
* @return The normalized version of the original expression
*
*/
public String toNormalizedString() {
String normalized = "";
normalized = "(" + jjtGetChild(0).toNormalizedString() + " "
+ getTokenImage(ParserConstants.UNION) + " "
+ jjtGetChild(1).toNormalizedString() + ")";
return normalized;
}
/**
* This method evaluates this node of the expression and all child nodes.
* It returns the result of the
* evaluation as an <tt>Object</tt>. If any problems are encountered
* during the evaluation, an <tt>EvaluationException</tt> is thrown.
*
*
* @param pageContext the current JSP PageContext
*
* @param icontext the Iteration Context of the expression. If there is
* no interation context, this should be null.
*
* @return the result of the expression evaluation as an object
*
* @throws EvaluationException if a problem is encountered during the
* evaluation
*/
public Object evaluate(PageContext pageContext, IterationContext icontext)
throws EvaluationException {
JSPList result;
try {
JSPList leftSide =
Convert.toJSPList(jjtGetChild(0).evaluate(pageContext,
icontext));
JSPList rightSide =
Convert.toJSPList(jjtGetChild(1).evaluate(pageContext,
icontext));
result = new JSPListUnion(leftSide, rightSide);
} catch (ConversionException ce) {
throw new EvaluationException(this, ce.getMessage());
}
return result;
}
}