package mightypork.util.control.eventbus; import java.util.Collection; import java.util.HashSet; import mightypork.util.control.eventbus.clients.DelegatingClient; import mightypork.util.control.eventbus.clients.ToggleableClient; import mightypork.util.logging.Log; /** * Event delivery channel, module of {@link EventBus} * * @author MightyPork * @param event type * @param client (subscriber) type */ class EventChannel, CLIENT> { private final Class clientClass; private final Class eventClass; /** * Create a channel * * @param eventClass event class * @param clientClass client class */ public EventChannel(Class eventClass, Class clientClass) { if (eventClass == null || clientClass == null) { throw new NullPointerException("Null Event or Client class."); } this.clientClass = clientClass; this.eventClass = eventClass; } /** * Try to broadcast a event.
* If event is of wrong type, false is returned. * * @param event a event to be sent * @param clients collection of clients */ public void broadcast(BusEvent event, Collection clients) { if (!canBroadcast(event)) return; doBroadcast(eventClass.cast(event), clients, new HashSet<>()); } /** * Send the event * * @param event sent event * @param clients subscribing clients * @param processed clients already processed */ private void doBroadcast(final EVENT event, final Collection clients, final Collection processed) { for (final Object client : clients) { // exclude obvious non-clients if (!isClientValid(client)) { continue; } // avoid executing more times if (processed.contains(client)) { Log.w(EventBus.logMark + "Client already served: " + Log.str(client)); continue; } processed.add(client); // opt-out if (client instanceof ToggleableClient) { if (!((ToggleableClient) client).isListening()) continue; } sendTo(client, event); if (event.isConsumed()) return; // pass on to delegated clients if (client instanceof DelegatingClient) { if (((DelegatingClient) client).doesDelegate()) { final Collection children = ((DelegatingClient) client).getChildClients(); if (children != null && children.size() > 0) { doBroadcast(event, children, processed); } } } } } /** * Send an event to a client. * * @param client target client * @param event event to send */ @SuppressWarnings("unchecked") private void sendTo(Object client, EVENT event) { if (isClientOfChannelType(client)) { ((BusEvent) event).deliverTo((CLIENT) client); } } /** * Check if the given event can be broadcasted by this channel * * @param event event object * @return can be broadcasted */ public boolean canBroadcast(BusEvent event) { return event != null && eventClass.isInstance(event); } /** * Create an instance for given types * * @param eventClass event class * @param clientClass client class * @return the broadcaster */ public static , F_CLIENT> EventChannel create(Class eventClass, Class clientClass) { return new EventChannel<>(eventClass, clientClass); } /** * Check if client is of channel type * * @param client client * @return is of type */ private boolean isClientOfChannelType(Object client) { return clientClass.isInstance(client); } /** * Check if the channel is compatible with given * * @param client client * @return is supported */ public boolean isClientValid(Object client) { return isClientOfChannelType(client) || (client instanceof DelegatingClient); } @Override public int hashCode() { final int prime = 13; int result = 1; result = prime * result + ((clientClass == null) ? 0 : clientClass.hashCode()); result = prime * result + ((eventClass == null) ? 0 : eventClass.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (!(obj instanceof EventChannel)) return false; final EventChannel other = (EventChannel) obj; if (clientClass == null) { if (other.clientClass != null) return false; } else if (!clientClass.equals(other.clientClass)) return false; if (eventClass == null) { if (other.eventClass != null) return false; } else if (!eventClass.equals(other.eventClass)) return false; return true; } @Override public String toString() { return "{ " + Log.str(eventClass) + " => " + Log.str(clientClass) + " }"; } }