/*
* 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.
*/
/*
* $Id: PluggableLookupCommand.java 473876 2006-11-12 04:50:13Z gvanmatre $
*/
package org.apache.shale.clay.utils;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import org.apache.commons.chain.Catalog;
import org.apache.commons.chain.CatalogFactory;
import org.apache.commons.chain.Command;
import org.apache.commons.chain.Context;
import org.apache.commons.chain.generic.LookupCommand;
/**
* <p>This chains class performs a check to verify the catalog exists.
* If the catalog doesn't exist, it returns <code>true</code> if the
* <code>optional</code> property in the super class is <code>true</code>.
* If the catalog is not found and the command is not optional, it returns a
* <code>false</code> value. Otherwise, if the catalog exists, the super
* implementation is invoked. The name of the command can be a value
* binding expression. The value is evaluated if it contains an expression
* and the resolved command is invoked.</p>
*
*/
public class PluggableLookupCommand extends LookupCommand {
/**
* <p>Checks to see if the catalog exists.</p>
*
* @return <code>true</code> if the catalog exists
*/
private boolean catalogExists() {
String catalogName = getCatalogName();
if (catalogName == null) {
return false;
}
CatalogFactory catalogFactory = CatalogFactory.getInstance();
return (catalogFactory.getCatalog(catalogName) != null);
}
/**
* @return <code>Catalog</code> for the <code>catalogName</code>
*/
private Catalog getCatalog() {
CatalogFactory catalogFactory = CatalogFactory.getInstance();
return catalogFactory.getCatalog(getCatalogName());
}
/**
* <p>Adds an additional check to determine if the catalog name is loaded.
* If loaded, the super implementation is invoked. Otherwise, the chain
* continues if the command is optional.</p>
*
* @param context chains context
* @return <code>true</code> if the chain is done
* @exception Exception up the calling chain
*/
public boolean execute(Context context) throws Exception {
if (!catalogExists()) {
return !isOptional();
}
if (isValueReference(getName())) {
// command is a binding expression; evaluate and the find the target command
FacesContext facesContext = FacesContext.getCurrentInstance();
ValueBinding vb = facesContext.getApplication().createValueBinding(getName());
String targetCommand = (String) vb.getValue(facesContext);
if (targetCommand != null) {
Command command = getCatalog().getCommand(targetCommand);
if (command != null) {
return command.execute(context);
}
}
}
return super.execute(context);
}
/**
* @param value the command name to test for a binding expression
* @return <code>true</code> if the <code>value</code> is a binding expression
*/
private boolean isValueReference(String value) {
if (value == null) {
return false;
}
if ((value.indexOf("#{") > -1)
&& (value.indexOf("}") > -1)) {
return true;
}
return false;
}
}