PdDispatcher.java

/**
 * 
 * For information on usage and redistribution, and for a DISCLAIMER OF ALL
 * WARRANTIES, see the file, "LICENSE.txt," in this distribution.
 * 
 */

package org.puredata.core.utils;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.puredata.core.PdBase;
import org.puredata.core.PdListener;
import org.puredata.core.PdReceiver;

/**
 * 
 * PdDispatcher is an implementation of {@link PdReceiver} that dispatches messages from Pd to instances of
 * {@link PdListener} based on the Pd symbol they originate from.  Instances of this class automatically
 * handle subscriptions to Pd symbols.
 * 
 * @author Peter Brinkmann (peter.brinkmann@gmail.com) 
 *
 */
public abstract class PdDispatcher implements PdReceiver {

	private final Map<String, Set<PdListener>> listeners = new HashMap<String, Set<PdListener>>();

	/**
	 * Register a listener for Pd messages to the given symbol; subscribe to the symbol if this is
	 * the first listener for this symbol
	 * 
	 * @param symbol    receiver symbol in Pd
	 * @param listener
	 */
	public synchronized void addListener(String symbol, PdListener listener) {
		Set<PdListener> selected = listeners.get(symbol);
		if (selected == null) {
			int err = PdBase.subscribe(symbol);
			if (err != 0) {
				throw new IllegalArgumentException("bad symbol: " + symbol);
			}
			selected = new HashSet<PdListener>();
			listeners.put(symbol, selected);
		}
		selected.add(listener);
	}
	
	/**
	 * Remove a listener associated with a symbol; unsubscribe from Pd messages to symbol
     * if no listeners are left
	 * 
	 * @param symbol    receiver symbol in Pd
	 * @param listener
	 */
	public synchronized void removeListener(String symbol, PdListener listener) {
		Set<PdListener> selected = listeners.get(symbol);
		if (selected != null) {
			selected.remove(listener);
			if (selected.isEmpty()) {
				PdBase.unsubscribe(symbol);
				listeners.remove(symbol);
			}
		}
    }
	
	/**
	 * Unsubscribe from Pd messages and release all resources
	 */
	public synchronized void release() {
		for (String symbol: listeners.keySet()) {
			PdBase.unsubscribe(symbol);
		}
		listeners.clear();
	}
	
	@Override
	protected void finalize() throws Throwable {
		release();
		super.finalize();
	}
	
	/**
	 * Handle print messages from Pd
	 */
	@Override
	public abstract void print(String s);

	@Override
	public synchronized void receiveBang(String source) {
		Set<PdListener> selected = listeners.get(source);
		if (selected != null) {
			for (PdListener listener: selected) {
				listener.receiveBang(source);
			}
		}
	}

	@Override
	public synchronized void receiveFloat(String source, float x) {
		Set<PdListener> selected = listeners.get(source);
		if (selected != null) {
			for (PdListener listener: selected) {
				listener.receiveFloat(source, x);
			}
		}
	}
	
	@Override
	public synchronized void receiveSymbol(String source, String symbol) {
		Set<PdListener> selected = listeners.get(source);
		if (selected != null) {
			for (PdListener listener: selected) {
				listener.receiveSymbol(source, symbol);
			}
		}
	}

	@Override
	public synchronized void receiveList(String source, Object... args) {
		Set<PdListener> selected = listeners.get(source);
		if (selected != null) {
			for (PdListener listener: selected) {
				listener.receiveList(source, args);
			}
		}
	}

	@Override
	public synchronized void receiveMessage(String source, String symbol, Object... args) {
		Set<PdListener> selected = listeners.get(source);
		if (selected != null) {
			for (PdListener listener: selected) {
				listener.receiveMessage(source, symbol, args);
			}
		}
	}
}