/*
* $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/expression/jexl/JexlExpression.java,v 1.9 2002/07/22 14:34:09 jstrachan Exp $
* $Revision: 1.9 $
* $Date: 2002/07/22 14:34:09 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2002 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* $Id: JexlExpression.java,v 1.9 2002/07/22 14:34:09 jstrachan Exp $
*/
package org.apache.commons.jelly.expression.jexl;
import java.util.Map;
import java.util.Set;
import java.util.Collection;
import org.apache.commons.jelly.JellyContext;
import org.apache.commons.jelly.expression.ExpressionSupport;
import org.apache.commons.jexl.Expression;
import org.apache.commons.jexl.JexlContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Represents a <a href="http://jakarta.apache.org/commons/jexl.html">Jexl</a>
* expression which fully supports the Expression Language in JSTL and JSP
* along with some extra features like object method invocation.
*
* @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
* @version $Revision: 1.9 $
*/
public class JexlExpression extends ExpressionSupport {
/** The Log to which logging calls will be made. */
private static final Log log = LogFactory.getLog(JexlExpression.class);
/** The Jexl expression object */
private Expression expression;
public JexlExpression(Expression expression) {
this.expression = expression;
}
// Expression interface
//-------------------------------------------------------------------------
public Object evaluate(JellyContext context) {
try {
JexlContext jexlContext = new JellyJexlContext( context );
if (log.isDebugEnabled()) {
log.debug("Evaluating EL: " + expression);
}
return expression.evaluate(jexlContext);
}
catch (Exception e) {
log.warn("Caught exception evaluating: " + expression + ". Reason: " + e, e);
return null;
}
}
}
class JellyJexlContext implements JexlContext {
private Map vars;
JellyJexlContext(JellyContext context) {
this.vars = new JellyMap( context );
}
public void setVars(Map vars) {
this.vars.clear();
this.vars.putAll( vars );
}
public Map getVars() {
return this.vars;
}
}
class JellyMap implements Map {
private JellyContext context;
JellyMap(JellyContext context) {
this.context = context;
}
public Object get(Object key) {
return context.findVariable( (String) key );
}
public void clear() {
// not implemented
}
public boolean containsKey(Object key) {
return ( get( key ) != null );
}
public boolean containsValue(Object value) {
return false;
}
public Set entrySet() {
return null;
}
public boolean isEmpty() {
return false;
}
public Set keySet() {
return null;
}
public Object put(Object key, Object value) {
return null;
}
public void putAll(Map t) {
// not implemented
}
public Object remove(Object key) {
return null;
}
public int size() {
return -1;
}
public Collection values() {
return null;
}
}