/*
* 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.shindig.gadgets.templates;
import org.apache.shindig.expressions.Expressions;
import org.apache.shindig.gadgets.spec.MessageBundle;
import java.beans.FeatureDescriptor;
import java.util.Iterator;
import java.util.List;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.PropertyNotWritableException;
import com.google.common.collect.Lists;
/**
* ELResolver for the Msg property in templates.
*/
public class MessageELResolver extends ELResolver {
public static final String PROPERTY_MSG = "Msg";
private final MessageBundle bundle;
private final Expressions expressions;
public MessageELResolver(Expressions expressions, MessageBundle bundle) {
this.expressions = expressions;
this.bundle = bundle;
}
@Override
public Class<?> getCommonPropertyType(ELContext context, Object base) {
if (base == null) {
return String.class;
}
return null;
}
@Override
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,
Object base) {
return null;
}
@Override
public Class<?> getType(ELContext context, Object base, Object property) {
// TODO: implement
return null;
}
@Override
public Object getValue(ELContext context, Object base, Object property) {
if ((base == null) && PROPERTY_MSG.equals(property)) {
context.setPropertyResolved(true);
return bundle;
} else if (base instanceof MessageBundle) {
String text = bundle.getMessages().get(property);
if (text == null) {
context.setPropertyResolved(true);
return null;
}
List<Object> properties = null;
try {
properties = pushCurrentProperty(context, property);
context.setPropertyResolved(false);
return expressions.parse(text, Object.class).getValue(context);
} finally {
popProperty(properties);
context.setPropertyResolved(true);
}
}
return null;
}
/**
* Track the set of message bundle properties being evaluated. We allow
* recursion, but don't want to allow infinite self-recursion (though the
* stack overflows quickly).
*/
private List<Object> pushCurrentProperty(ELContext context, Object property) {
@SuppressWarnings("unchecked")
List<Object> propertyList = (List<Object>) context.getContext(MessageELResolver.class);
if (propertyList == null) {
propertyList = Lists.newArrayList();
context.putContext(MessageELResolver.class, propertyList);
} else {
if (propertyList.contains(property)) {
throw new ELException("Recursive invocation of message bundle properties");
}
}
propertyList.add(property);
return propertyList;
}
private void popProperty(List<Object> properties) {
if (properties != null) {
properties.remove(properties.size() - 1);
}
}
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
if ((base == null) && PROPERTY_MSG.equals(property)) {
context.setPropertyResolved(true);
return true;
}
return false;
}
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
if ((base == null) && PROPERTY_MSG.equals(property)) {
throw new PropertyNotWritableException();
}
}
}