org.apache.commons.jexl.parser.ASTReference Maven / Gradle / Ivy
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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.
*/
package org.apache.commons.jexl.parser;
import org.apache.commons.jexl.JexlContext;
/**
* reference - any variable expression.
*
* @author Geir Magnusson Jr.
* @version $Id: ASTReference.java 480412 2006-11-29 05:11:23Z bayard $
*/
public class ASTReference extends SimpleNode {
/** first variable in the expression. */
protected SimpleNode root;
/**
* Create the node given an id.
*
* @param id node id.
*/
public ASTReference(int id) {
super(id);
}
/**
* Create a node with the given parser and id.
*
* @param p a parser.
* @param id node id.
*/
public ASTReference(Parser p, int id) {
super(p, id);
}
/** {@inheritDoc} */
public Object jjtAccept(ParserVisitor visitor, Object data) {
return visitor.visit(this, data);
}
/** {@inheritDoc} */
public Object value(JexlContext jc) throws Exception {
return execute(null, jc);
}
/** Store the first child as {@link ASTReference#root root}. */
public void jjtClose() {
root = (SimpleNode) jjtGetChild(0);
}
/**
* evaluate each piece of the reference.
*
* e.g. foo.bar.woogie[2].name, foo is our 'root', and we need to
* evaluate 'bar.woogie[2].name' relative to foo.
*
* @param jc the {@link JexlContext} to evaluate against.
* @param obj not used. root.value(jc) is used instead.
* @return the value of the array expression.
* @throws Exception on any error
*/
public Object execute(Object obj, JexlContext jc) throws Exception {
Object o = root.value(jc);
/*
* ignore the first child - it's our identifier
*/
for (int i = 1; i < jjtGetNumChildren(); i++) {
o = ((SimpleNode) jjtGetChild(i)).execute(o, jc);
// check for a variable in the context named
// child0.child1.child2 etc
if (o == null) {
String varName = getIdentifierToDepth(i);
o = jc.getVars().get(varName);
}
}
return o;
}
/**
* This method returns a variable from this identifier and it's children.
* For an expression like 'a.b.c', a is child zero, b is child 1 and c is
* child 2.
*
* @param i the depth of the child nodes to go to
* @return the a dotted variable from this identifier and it's child nodes.
*/
private String getIdentifierToDepth(int i) {
StringBuffer varName = new StringBuffer();
for (int j = 0; j <= i; j++) {
SimpleNode node = (SimpleNode) jjtGetChild(j);
if (node instanceof ASTIdentifier) {
varName.append(((ASTIdentifier) node).getIdentifierString());
if (j != i) {
varName.append('.');
}
}
}
return varName.toString();
}
/**
* Gets the variable name of {@link ASTReference#root root}.
* @return the identifier.
* @throws Exception on any error
* @see ASTIdentifier#getIdentifierString()
* @see ASTArrayAccess#getIdentifierString()
*/
public String getRootString() throws Exception {
if (root instanceof ASTIdentifier) {
return ((ASTIdentifier) root).getIdentifierString();
}
if (root instanceof ASTArrayAccess) {
return ((ASTArrayAccess) root).getIdentifierString();
}
throw new Exception("programmer error : ASTReference : root not known" + root);
}
}