// ========================================================================
// Copyright (c) 2005-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
package org.eclipse.jetty.util.component;
import java.lang.ref.WeakReference;
import java.util.EventListener;
import java.util.concurrent.CopyOnWriteArrayList;
import org.eclipse.jetty.util.LazyList;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/* ------------------------------------------------------------ */
/** Container.
* This class allows a containment events to be generated from update methods.
*
* The style of usage is: <pre>
* public void setFoo(Foo foo)
* {
* getContainer().update(this,this.foo,foo,"foo");
* this.foo=foo;
* }
*
* public void setBars(Bar[] bars)
* {
* getContainer().update(this,this.bars,bars,"bar");
* this.bars=bars;
* }
* </pre>
*/
public class Container
{
private static final Logger LOG = Log.getLogger(Container.class);
private final CopyOnWriteArrayList<Container.Listener> _listeners=new CopyOnWriteArrayList<Container.Listener>();
public void addEventListener(Container.Listener listener)
{
_listeners.add(listener);
}
public void removeEventListener(Container.Listener listener)
{
_listeners.remove(listener);
}
/* ------------------------------------------------------------ */
/** Update single parent to child relationship.
* @param parent The parent of the child.
* @param oldChild The previous value of the child. If this is non null and differs from <code>child</code>, then a remove event is generated.
* @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
* @param relationship The name of the relationship
*/
public void update(Object parent, Object oldChild, final Object child, String relationship)
{
if (oldChild!=null && !oldChild.equals(child))
remove(parent,oldChild,relationship);
if (child!=null && !child.equals(oldChild))
add(parent,child,relationship);
}
/* ------------------------------------------------------------ */
/** Update single parent to child relationship.
* @param parent The parent of the child.
* @param oldChild The previous value of the child. If this is non null and differs from <code>child</code>, then a remove event is generated.
* @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
* @param relationship The name of the relationship
* @param addRemove If true add/remove is called for the new/old children as well as the relationships
*/
public void update(Object parent, Object oldChild, final Object child, String relationship,boolean addRemove)
{
if (oldChild!=null && !oldChild.equals(child))
{
remove(parent,oldChild,relationship);
if (addRemove)
removeBean(oldChild);
}
if (child!=null && !child.equals(oldChild))
{
if (addRemove)
addBean(child);
add(parent,child,relationship);
}
}
/* ------------------------------------------------------------ */
/** Update multiple parent to child relationship.
* @param parent The parent of the child.
* @param oldChildren The previous array of children. A remove event is generated for any child in this array but not in the <code>children</code> array.
* This array is modified and children that remain in the new children array are nulled out of the old children array.
* @param children The current array of children. An add event is generated for any child in this array but not in the <code>oldChildren</code> array.
* @param relationship The name of the relationship
*/
public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship)
{
update(parent,oldChildren,children,relationship,false);
}
/* ------------------------------------------------------------ */
/** Update multiple parent to child relationship.
* @param parent The parent of the child.
* @param oldChildren The previous array of children. A remove event is generated for any child in this array but not in the <code>children</code> array.
* This array is modified and children that remain in the new children array are nulled out of the old children array.
* @param children The current array of children. An add event is generated for any child in this array but not in the <code>oldChildren</code> array.
* @param relationship The name of the relationship
* @param addRemove If true add/remove is called for the new/old children as well as the relationships
*/
public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship, boolean addRemove)
{
Object[] newChildren = null;
if (children!=null)
{
newChildren = new Object[children.length];
for (int i=children.length;i-->0;)
{
boolean new_child=true;
if (oldChildren!=null)
{
for (int j=oldChildren.length;j-->0;)
{
if (children[i]!=null && children[i].equals(oldChildren[j]))
{
oldChildren[j]=null;
new_child=false;
}
}
}
if (new_child)
newChildren[i]=children[i];
}
}
if (oldChildren!=null)
{
for (int i=oldChildren.length;i-->0;)
{
if (oldChildren[i]!=null)
{
remove(parent,oldChildren[i],relationship);
if (addRemove)
removeBean(oldChildren[i]);
}
}
}
if (newChildren!=null)
{
for (int i=0;i<newChildren.length;i++)
if (newChildren[i]!=null)
{
if (addRemove)
addBean(newChildren[i]);
add(parent,newChildren[i],relationship);
}
}
}
/* ------------------------------------------------------------ */
public void addBean(Object obj)
{
if (_listeners!=null)
{
for (int i=0; i<LazyList.size(_listeners); i++)
{
Listener listener=(Listener)LazyList.get(_listeners, i);
listener.addBean(obj);
}
}
}
/* ------------------------------------------------------------ */
public void removeBean(Object obj)
{
if (_listeners!=null)
{
for (int i=0; i<LazyList.size(_listeners); i++)
((Listener)LazyList.get(_listeners, i)).removeBean(obj);
}
}
/* ------------------------------------------------------------ */
/** Add a parent child relationship
* @param parent
* @param child
* @param relationship
*/
private void add(Object parent, Object child, String relationship)
{
if (LOG.isDebugEnabled())
LOG.debug("Container "+parent+" + "+child+" as "+relationship);
if (_listeners!=null)
{
Relationship event=new Relationship(this,parent,child,relationship);
for (int i=0; i<LazyList.size(_listeners); i++)
((Listener)LazyList.get(_listeners, i)).add(event);
}
}
/* ------------------------------------------------------------ */
/** remove a parent child relationship
* @param parent
* @param child
* @param relationship
*/
private void remove(Object parent, Object child, String relationship)
{
if (LOG.isDebugEnabled())
LOG.debug("Container "+parent+" - "+child+" as "+relationship);
if (_listeners!=null)
{
Relationship event=new Relationship(this,parent,child,relationship);
for (int i=0; i<LazyList.size(_listeners); i++)
((Listener)LazyList.get(_listeners, i)).remove(event);
}
}
/* ------------------------------------------------------------ */
/** A Container event.
* @see Listener
*/
public static class Relationship
{
private final WeakReference<Object> _parent;
private final WeakReference<Object> _child;
private String _relationship;
private Container _container;
private Relationship(Container container, Object parent,Object child, String relationship)
{
_container=container;
_parent=new WeakReference<Object>(parent);
_child=new WeakReference<Object>(child);
_relationship=relationship;
}
public Container getContainer()
{
return _container;
}
public Object getChild()
{
return _child.get();
}
public Object getParent()
{
return _parent.get();
}
public String getRelationship()
{
return _relationship;
}
@Override
public String toString()
{
return _parent+"---"+_relationship+"-->"+_child;
}
@Override
public int hashCode()
{
return _parent.hashCode()+_child.hashCode()+_relationship.hashCode();
}
@Override
public boolean equals(Object o)
{
if (o==null || !(o instanceof Relationship))
return false;
Relationship r = (Relationship)o;
return r._parent.get()==_parent.get() && r._child.get()==_child.get() && r._relationship.equals(_relationship);
}
}
/* ------------------------------------------------------------ */
/** Listener.
* A listener for Container events.
*/
public interface Listener extends EventListener
{
public void addBean(Object bean);
public void removeBean(Object bean);
public void add(Container.Relationship relationship);
public void remove(Container.Relationship relationship);
}
}