InterceptedValueHolder.java

package com.dragome.forms.bindings.client.value;

import com.dragome.forms.bindings.client.interceptor.Interceptor;
import com.dragome.forms.bindings.client.interceptor.InterceptorChain;
import com.dragome.forms.bindings.extra.user.client.Command;

/**
 * A ValueModel that can allows value changes to be intercepted by interested third parties.  The
 * interceptors can abort the value change if required.
 * 
 * @see #interceptUsing(com.pietschy.gwt.pectin.client.interceptor.Interceptor)
 */
public class InterceptedValueHolder<T> extends ValueHolder<T> implements InterceptedMutableValueModel<T>
{
	private InterceptorChain interceptors= new InterceptorChain();

	public InterceptedValueHolder()
	{
	}

	public InterceptedValueHolder(T value)
	{
		super(value);
	}

	@Override
	public void setValue(final T newValue)
	{
		setValueInternal(newValue, false);
	}

	public void setValue(final T newValue, boolean force)
	{
		setValueInternal(newValue, force);
	}

	private void setValueInternal(final T newValue, boolean force)
	{
		if (force)
		{
			super.setValue(newValue);
		}
		else
		{
			interceptors.execute(new Command()
			{
				public void execute()
				{
					InterceptedValueHolder.super.setValue(newValue);
				}
			});
		}
	}

	public void interceptUsing(Interceptor interceptor)
	{
		interceptors.addInterceptor(interceptor);
	}
}