EventSender.m

classdef (Abstract) EventSender < BaseCopyable
    % <EventSender> and <EventReceiver> are interfaces for inter-class communication.
    
    properties (Access = protected)
        listeners;  % Save the informations about the listeners (<event.listener>).
				% [optional] Remove some listeners when the listeners have been destoryed.
        targets;		% handle reference to the event target.
    end
    
    properties 
        Results;    % Used by <EventReceiver>, return the event handling results.
                    % The data structure is defined by <EventSender>, and should at least
                    % include a field named as 'Value'. <EventReceiver> should return
                    % infromation requested by <EventSender>.
    end
        
    methods
        function this = EventSender()
            this.listeners = ListArray('event.listener');
            this.targets = ListArray('EventReceiver');
        end
        
        function delete(this)
            delete(this.listeners);
        end
        
        %%%
        % |event_name|: cell array represents a set of events.
        function AddListener(this, target, event_name, callback)
            if ischar(event_name)
                event_name = {event_name};
            end
            idx = this.targets{:}==target;
						if ~isempty(idx)
							exist_events = this.listeners{idx,'EventName'};
						else
							exist_events = {};
						end
            for i = 1:length(event_name)
                if isempty(exist_events) || ~contains(event_name{i}, exist_events)
                    this.targets.Add(target);
                    this.listeners.Add(addlistener(this, event_name{i}, callback));
                    exist_events = [exist_events, event_name{i}]; %#ok<AGROW>
                end
            end
            %%
            % When notify listener (callback function), the EventData includes the Sender
            % and the Target of the event. In the callback function, the Target objects
            % can handle the event form the Sender.
        end
        
        % When slice is leaving, we should remove the slice form the listener's set
        function RemoveListener(this, target, event)
            idx = find(this.targets{:}==target);
            b_removed = false(length(this.listeners));
            if nargin >= 3
                for i = idx
                    if strcmp(this.listeners{i, 'EventName'},event)
                        b_removed(i) = true;
                    end
                end
            else
                b_removed(idx) = true;
            end
            this.listeners.Remove(b_removed);       % delete the listener objects;
            [~] = this.targets.Removed(b_removed);  % remove but not delete the targets;
				end
				
				function ClearListener(this)
					delete(this.listeners);
					this.listeners = ListArray('event.listener');
					this.targets.Clear();
				end
        
        function t = findTargets(this, ev_name)
            b_targets = false(length(this.listeners),1);
            for i = 1:length(this.listeners)
                if strcmp(this.listeners{i, 'EventName'}, ev_name)
                    b_targets(i) = true;
                end
            end
            t = this.targets{b_targets};
        end
    end
    
    methods (Access = protected)
			%% Copy the Listeners and Targets
			% After the default shallow copy, the new instance has the
			% same event targets as the current instance. 
			% However, the stored listeners in the 'newobj.listeners' instance is
			% the listeners of 'this'. Thus the listeners for the new instance
			% should be regenerated with the same set of targets as 'this'.
			%
			% After the copy is finished, the listeners might be changed outside.
			% Then we need to first <delete> the existing listeners and then add
			% new listeners.
        function newobj = copyElement(this)
					if this.isShallowCopyable
            newobj = copyElement@BaseCopyable(this);
					else
						newobj = this;
					end
					% Make a deep copy of the DeepCp object
					newobj.listeners = ListArray('event.listener');
					cprintf('Comments', 'info:[%s] copy listeners to the new object.\n', calledby);
					for i=1:newobj.targets.Length
						newobj.listeners.Add(addlistener(newobj, ...
							this.listeners{i, 'EventName'}, this.listeners{i, 'callback'}));
					end
				end
				
		end
end