org.apache.commons.jexl.parser.ASTArrayAccess 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 java.lang.reflect.Array;
import java.util.List;
import java.util.Map;
import org.apache.commons.jexl.JexlContext;
import org.apache.commons.jexl.util.Coercion;
import org.apache.commons.jexl.util.introspection.Info;
import org.apache.commons.jexl.util.introspection.Uberspect;
import org.apache.commons.jexl.util.introspection.VelPropertyGet;
/**
* Like an ASTIdentifier, but with array access allowed.
*
* $foo[2]
*
* @author Geir Magnusson Jr.
* @version $Id: ASTArrayAccess.java 548229 2007-06-18 06:11:32Z dion $
*/
public class ASTArrayAccess extends SimpleNode {
/** dummy velocity info. */
private static final Info DUMMY = new Info("", 1, 1);
/**
* Create the node given an id.
*
* @param id node id.
*/
public ASTArrayAccess(int id) {
super(id);
}
/**
* Create a node with the given parser and id.
*
* @param p a parser.
* @param id node id.
*/
public ASTArrayAccess(Parser p, int id) {
super(p, id);
}
/** {@inheritDoc} */
public Object jjtAccept(ParserVisitor visitor, Object data) {
return visitor.visit(this, data);
}
/**
* evaluate array access upon a base object.
*
* foo.bar[2]
*
* makes me rethink the array operator :)
* @param jc the {@link JexlContext} to evaluate against.
* @param obj not used.
* @return the value of the array expression.
* @throws Exception on any error
*/
public Object execute(Object obj, JexlContext jc) throws Exception {
ASTIdentifier base = (ASTIdentifier) jjtGetChild(0);
Object result = base.execute(obj, jc);
/*
* ignore the first child - it's our identifier
*/
for (int i = 1; i < jjtGetNumChildren(); i++) {
Object loc = ((SimpleNode) jjtGetChild(i)).value(jc);
if (loc == null) {
return null;
}
result = evaluateExpr(result, loc, getUberspect());
}
return result;
}
/** {@inheritDoc} */
public Object value(JexlContext jc) throws Exception {
/*
* get the base ASTIdentifier
*/
ASTIdentifier base = (ASTIdentifier) jjtGetChild(0);
Object o = base.value(jc);
/*
* ignore the first child - it's our identifier
*/
for (int i = 1; i < jjtGetNumChildren(); i++) {
Object loc = ((SimpleNode) jjtGetChild(i)).value(jc);
if (loc == null) {
return null;
}
o = evaluateExpr(o, loc, getUberspect());
}
return o;
}
/**
* Evaluate the Array expression 'loc' on the given object, o.
* e.g. in 'a[2]', 2 is 'loc' and a is 'o'.
*
* If o or loc are null, null is returned.
* If o is a Map, o.get(loc) is returned.
* If o is a List, o.get(loc) is returned. loc must resolve to an int value.
* If o is an Array, o[loc] is returned. loc must resolve to an int value.
* Otherwise loc is treated as a bean property of o.
*
* @param o an object to be accessed using the array operator or '.' operator.
* @param loc the index of the object to be returned.
* @param uberspect Uberspector to use during evaluation
* @return the resulting value.
* @throws Exception on any error.
*/
public static Object evaluateExpr(Object o, Object loc, Uberspect uberspect) throws Exception {
/*
* following the JSTL EL rules
*/
if (o == null) {
return null;
}
if (loc == null) {
return null;
}
if (o instanceof Map) {
if (!((Map) o).containsKey(loc)) {
return null;
}
return ((Map) o).get(loc);
} else if (o instanceof List) {
int idx = Coercion.coerceInteger(loc).intValue();
try {
return ((List) o).get(idx);
} catch (IndexOutOfBoundsException iobe) {
return null;
}
} else if (o.getClass().isArray()) {
int idx = Coercion.coerceInteger(loc).intValue();
try {
return Array.get(o, idx);
} catch (ArrayIndexOutOfBoundsException aiobe) {
return null;
}
} else {
/*
* "Otherwise (a JavaBean object)..." huh? :)
*/
String s = loc.toString();
VelPropertyGet vg = uberspect.getPropertyGet(o, s, DUMMY);
if (vg != null) {
return vg.invoke(o);
}
}
throw new Exception("Unsupported object type for array [] accessor");
}
/**
* Gets the variable name piece of the expression.
* @return a String of the identifer.
* @see ASTIdentifier#getIdentifierString().
*/
public String getIdentifierString() {
return ((ASTIdentifier) jjtGetChild(0)).getIdentifierString();
}
}