/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2003 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 acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation", "Tapestry"
* 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"
* or "Tapestry", nor may "Apache" or "Tapestry" appear in their
* name, without prior written permission of the Apache Software Foundation.
*
* 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 TAPESTRY CONTRIBUTOR COMMUNITY
* 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/>.
*
*/
package org.apache.tapestry.util;
import java.util.ArrayList;
import java.util.List;
import org.apache.tapestry.engine.IPropertySource;
/**
* An implementation of {@link org.apache.tapestry.IPropertySource}
* that delegates to a list of other implementations. This makes
* it possible to create a search path for property values.
*
* @author Howard Lewis Ship
* @version $Id: DelegatingPropertySource.java,v 1.1 2003/03/05 22:59:33 hlship Exp $
* @since 2.3
*
**/
public class DelegatingPropertySource implements IPropertySource
{
private List _sources = new ArrayList();
public DelegatingPropertySource()
{
}
public DelegatingPropertySource(IPropertySource delegate)
{
addSource(delegate);
}
/**
* Adds another source to the list of delegate property sources.
* This is typically only done during initialization
* of this DelegatingPropertySource.
*
**/
public void addSource(IPropertySource source)
{
_sources.add(source);
}
/**
* Re-invokes the method on each delegate property source,
* in order, return the first non-null value found.
*
**/
public String getPropertyValue(String propertyName)
{
String result = null;
int count = _sources.size();
for (int i = 0; i < count; i++)
{
IPropertySource source = (IPropertySource)_sources.get(i);
result = source.getPropertyValue(propertyName);
if (result != null)
break;
}
return result;
}
}