152 lines
4.2 KiB
Java
152 lines
4.2 KiB
Java
package com.github.nkzawa.emitter;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ConcurrentLinkedQueue;
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import java.util.concurrent.ConcurrentMap;
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/**
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* The event emitter which is ported from the JavaScript module.
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*
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* @see <a href="https://github.com/component/emitter">https://github.com/component/emitter</a>
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*/
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public class Emitter {
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private ConcurrentMap<String, ConcurrentLinkedQueue<Listener>> callbacks
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= new ConcurrentHashMap<String, ConcurrentLinkedQueue<Listener>>();
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private ConcurrentMap<Listener, Listener> onceCallbacks = new ConcurrentHashMap<Listener, Listener>();
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/**
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* Listens on the event.
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* @param event event name.
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* @param fn
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* @return a reference to to this object.
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*/
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public Emitter on(String event, Listener fn) {
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ConcurrentLinkedQueue<Listener> callbacks = this.callbacks.get(event);
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if (callbacks == null) {
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callbacks = new ConcurrentLinkedQueue <Listener>();
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ConcurrentLinkedQueue<Listener> _callbacks = this.callbacks.putIfAbsent(event, callbacks);
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if (_callbacks != null) {
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callbacks = _callbacks;
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}
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}
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callbacks.add(fn);
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return this;
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}
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/**
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* Adds a one time listener for the event.
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*
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* @param event
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* @param fn
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* @return a reference to to this object.
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*/
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public Emitter once(final String event, final Listener fn) {
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Listener on = new Listener() {
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@Override
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public void call(Object... args) {
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Emitter.this.off(event, this);
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fn.call(args);
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}
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};
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this.onceCallbacks.put(fn, on);
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this.on(event, on);
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return this;
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}
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/**
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* Removes all registered listeners.
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*
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* @return a reference to to this object.
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*/
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public Emitter off() {
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this.callbacks.clear();
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this.onceCallbacks.clear();
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return this;
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}
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/**
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* Removes all listeners of the specified event.
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*
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* @param event
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* @return a reference to to this object.
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*/
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public Emitter off(String event) {
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ConcurrentLinkedQueue<Listener> callbacks = this.callbacks.remove(event);
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if (callbacks != null) {
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for (Listener fn : callbacks) {
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this.onceCallbacks.remove(fn);
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}
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}
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return this;
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}
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/**
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* Removes the listener.
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*
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* @param event
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* @param fn
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* @return a reference to to this object.
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*/
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public Emitter off(String event, Listener fn) {
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ConcurrentLinkedQueue<Listener> callbacks = this.callbacks.get(event);
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if (callbacks != null) {
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Listener off = this.onceCallbacks.remove(fn);
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callbacks.remove(off != null ? off : fn);
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}
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return this;
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}
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/**
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* Executes each of listeners with the given args.
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*
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* @param event
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* @param args
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* @return a reference to to this object.
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*/
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public Emitter emit(String event, Object... args) {
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ConcurrentLinkedQueue<Listener> callbacks = this.callbacks.get(event);
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if (callbacks != null) {
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callbacks = new ConcurrentLinkedQueue<Listener>(callbacks);
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for (Listener fn : callbacks) {
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fn.call(args);
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}
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}
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return this;
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}
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/**
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* Returns a list of listeners for the specified event.
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*
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* @param event
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* @return a reference to to this object.
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*/
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public List<Listener> listeners(String event) {
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ConcurrentLinkedQueue<Listener> callbacks = this.callbacks.get(event);
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return callbacks != null ?
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new ArrayList<Listener>(callbacks) : new ArrayList<Listener>();
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}
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/**
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* Check if this emitter has listeners for the specified event.
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*
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* @param event
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* @return a reference to to this object.
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*/
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public boolean hasListeners(String event) {
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return !this.listeners(event).isEmpty();
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}
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public static interface Listener {
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public void call(Object... args);
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}
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}
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