Constructor.

This IView implementation is a Multiton, so you should not call the constructor directly, but instead call the static getInstance method.

• Throws MultitonErrorViewExists if instance for this Multiton key has already been constructed

View( String key )
{
  if (instanceMap[ key ] != null) throw new MultitonErrorViewExists();
  multitonKey = key;
  instanceMap[ multitonKey ] = this;
  mediatorMap = new Map<String,IMediator>();
  observerMap = new Map<String,List<IObserver>>();    
  initializeView();    
}

IView Multiton Factory method.

• Returns the IView Multiton instance for the specified key.

static IView getInstance( String key )
{
  if ( key == null || key == "" ) return null;
  if ( instanceMap == null ) instanceMap = new Map<String,IView>();
  if ( instanceMap[ key ] == null ) instanceMap[ key ] = new View( key );
  return instanceMap[ key ];
}

Remove an IView Multiton instance.

• Param key - the Multiton key of IView instance to remove.

static void removeView( String key )
{
    instanceMap[ key ] = null;
}

Check if an IMediator is registered with the IView.

• Param mediatorName - the name of the IMediator you're looking for.
• Returns bool - whether an IMediator is registered in this core with the given mediatorName.

bool hasMediator( String mediatorName )
{
    return mediatorMap[ mediatorName ] != null;
}

Initialize the Multiton View instance.

Called automatically by the constructor, this is your opportunity to initialize the Multiton instance in your subclass without overriding the constructor.

void initializeView(  ){}

Notify the IObservers for a particular INotification.

All previously attached IObservers for this INotification's list are notified and are passed a reference to the INotification in the order in which they were registered.

• Param note - the INotification to notify IObservers of.

void notifyObservers( INotification note )
{
  // Get a reference to the observers list for this notification name
  List<IObserver> observers_ref = observerMap[ note.getName() ];
  if( observers_ref != null ) 
  {
    // Copy observers from reference array to working array, 
    // since the reference array may change during the notification loop
    List<IObserver> observers = new List<IObserver>(); 
    IObserver observer;
    for (var i = 0; i < observers_ref.length; i++) { 
      observer = observers_ref[ i ];
      observers.add( observer );
    }
      
    // Notify Observers from the working array                
    for (var i = 0; i < observers.length; i++) {
        observer = observers[ i ];
        observer.notifyObserver( note );
    }
  }
}

Register an IMediator instance with the IView.

Registers the IMediator so that it can be retrieved by name, and interrogates the IMediator for its INotification interests.

If the IMediator returns a list of INotification names to be notified about, an Observer is created encapsulating the IMediator instance's handleNotification method and registering it as an IObserver for all INotifications the IMediator is interested in.

• Param mediator - a reference to the IMediator instance.

void registerMediator( IMediator mediator )
{
  // do not allow re-registration (you must call removeMediator first)
  if ( mediatorMap[ mediator.getName() ] != null ) return;
  
  // Initialize with multiton key
  mediator.initializeNotifier( multitonKey );

  // Register the Mediator for retrieval by name
  mediatorMap[ mediator.getName() ] = mediator;
  
  // Get Notification interests, if any.
  List<String> interests = mediator.listNotificationInterests();

  // Register Mediator as an observer for each notification of interests
  if ( interests.length > 0 ) 
  {
    // Create Observer referencing this mediator's handlNotification method
    IObserver observer = new Observer( mediator.handleNotification, mediator );

    // Register Mediator as Observer for its list of Notification interests
    for ( var i=0;  i<interests.length; i++ ) {
        registerObserver( interests[i],  observer );
    }            
  }
  
  // alert the mediator that it has been registered
  mediator.onRegister();
}

Register an IObserver to be notified of INotifications with a given name.

• Param noteName - the name of the INotification to notify this IObserver of.
• Param observer - the IObserver to register.

void registerObserver( String noteName, IObserver observer )
{
  if( observerMap[ noteName ] == null ) {
    observerMap[ noteName ] = new List<IObserver>();
  }
  observerMap[ noteName ].add( observer );
}

Remove an IMediator from the IView.

• Param mediatorName - name of the IMediator instance to be removed.
• Returns IMediator - the IMediator that was removed from this core's IView.

IMediator removeMediator( String mediatorName )
{
    // Retrieve the named mediator
    IMediator mediator = mediatorMap[ mediatorName ];
    
    if ( mediator != null ) 
    {
      // for every notification this mediator is interested in...
      List<String> interests = mediator.listNotificationInterests();
      for ( var i=0; i<interests.length; i++ ) 
      {
        // remove the observer linking the mediator 
        // to the notification interest
        removeObserver( interests[i], mediator );
      }    
      
      // remove the mediator from the map        
      mediatorMap[ mediatorName ] = null;

      // alert the mediator that it has been removed
      mediator.onRemove();
    }
    
    return mediator;
}

Remove an IObserver from the list for a given INotification name.

• Param noteName - which IObserver list to remove from.
• Param notifyContext - remove IObservers with this object as the notifyContext.

void removeObserver( String noteName, Object notifyContext )
{
    // the observer list for the notification under inspection
    List<IObserver> observers = observerMap[ noteName ];

    // find the observer for the notifyContext
    for ( var i=0; i<observers.length; i++ ) 
    {
        if ( observers[i].compareNotifyContext( notifyContext ) == true ) 
        {
            // there can only be one Observer for a given notifyContext 
            // in any given Observer list, so remove it and break
            observers.removeRange(i, 1);
            break;
        }
    }

    // Also, when a Notification's Observer list length falls to 
    // zero, delete the notification key from the observer map
    if ( observers.length == 0 ) {
        observerMap[ noteName ] = null;        
    }
}

Retrieve an IMediator from the IView.

• Param mediatorName - the name of the IMediator instance to retrieve.
• Returns IMediator - the IMediator instance previously registered in this core with the given mediatorName.

IMediator retrieveMediator( String mediatorName )
{
    return mediatorMap[ mediatorName ];
}