BasePresenter.java

/*
 * Copyright (c) 2009, Paul Merlin. All Rights Reserved.
 *
 * Licensed 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.swing.on.steroids.presenters;

import java.util.HashSet;
import java.util.Set;

import org.swing.on.steroids.messagebus.Subscribtion;
import org.swing.on.steroids.views.handlers.HandlerRegistration;
import org.swing.on.steroids.views.View;

/**
 * Base class to implement Presenters that provide common code, mostly Handler & Subscription related.
 *
 * @param <V> View type required by this Presenter.
 */
public abstract class BasePresenter<V extends View>
        implements Presenter
{

    private boolean bound = false;
    private Set<HandlerRegistration> viewHandlerRegistrations = new HashSet<HandlerRegistration>();
    private Set<Subscribtion> messageSubscribtions = new HashSet<Subscribtion>();
    protected final V view;

    protected BasePresenter( V view )
    {
        this.view = view;
    }

    @Override
    public final V view()
    {
        return view;
    }

    @Override
    public synchronized final void bind()
    {
        if ( !bound ) {
            onBind();
            bound = true;
        }
    }

    @Override
    public synchronized final void unbind()
    {
        if ( bound ) {
            onUnbind();
            for ( HandlerRegistration eachViewRegistration : viewHandlerRegistrations ) {
                eachViewRegistration.removeHandler();
            }
            for ( Subscribtion subscribtion : messageSubscribtions ) {
                subscribtion.unsubscribe();
            }
            bound = false;
        }
    }

    /**
     * Called when the Presenter has to be bound to its views and other participants. Subtypes must implement this.
     */
    protected abstract void onBind();

    /**
     * Called when the Presenter has to be unbound from its views and other participants. Subtypes must implement this.
     */
    protected abstract void onUnbind();

    /**
     * HandlerRegistration recorded with this method will automatically be removed on unbind.
     * @param viewRegistration HandlerRegistration to be recorded.
     */
    protected final void recordViewRegistration( HandlerRegistration viewRegistration )
    {
        viewHandlerRegistrations.add( viewRegistration );
    }

    /**
     * Subscribtion recorded with this method will automatically be unsubscribed on unbind.
     * @param subscribtion Subscribtion
     */
    protected final void recordMessageSubscribtion( Subscribtion subscribtion )
    {
        messageSubscribtions.add( subscribtion );
    }

}