de.xaniox.heavyspleef.core.event.EventBus.java Source code

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Here is the source code for de.xaniox.heavyspleef.core.event.EventBus.java

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/*
 * This file is part of HeavySpleef.
 * Copyright (c) 2014-2016 Matthias Werning
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package de.xaniox.heavyspleef.core.event;

import com.google.common.collect.Sets;

import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

public class EventBus {

    private final Logger logger;
    private Set<EventListenerMethod> registeredEventListeners;

    protected EventBus(Logger logger) {
        this.logger = logger;
        this.registeredEventListeners = Sets.newTreeSet();
    }

    public void registerListener(SpleefListener listener) {
        registerListener(listener, false);
    }

    public void registerListener(SpleefListener listener, boolean registerSuper) {
        Class<? extends SpleefListener> clazz = listener.getClass();

        do {
            Method[] methods = clazz.getDeclaredMethods();
            for (Method method : methods) {
                if (!method.isAnnotationPresent(Subscribe.class)) {
                    continue;
                }

                validateMethod(method);

                EventListenerMethod listenerMethodHolder = new EventListenerMethod(listener, method);
                registeredEventListeners.add(listenerMethodHolder);
            }

            Class<?> superclass = clazz.getSuperclass();
            if (!SpleefListener.class.isAssignableFrom(superclass)) {
                break;
            }

            clazz = superclass.asSubclass(SpleefListener.class);
        } while (registerSuper);
    }

    public void unregister(SpleefListener listener) {
        Iterator<EventListenerMethod> methodIterator = registeredEventListeners.iterator();
        while (methodIterator.hasNext()) {
            EventListenerMethod method = methodIterator.next();
            if (!method.getMethodClass().isInstance(listener)) {
                continue;
            }

            methodIterator.remove();
        }
    }

    protected boolean isRegistered(SpleefListener listener) {
        for (EventListenerMethod method : registeredEventListeners) {
            if (method.getEventClass() == listener.getClass()) {
                return true;
            }
        }

        return false;
    }

    public void callEvent(Event event) {
        for (EventListenerMethod method : registeredEventListeners) {
            if (!method.getEventClass().isInstance(event)) {
                continue;
            }

            try {
                method.invoke(event);
            } catch (Throwable t) {
                logger.log(Level.SEVERE, "Could not pass " + event.getClass().getSimpleName() + " in class "
                        + method.getMethodClass().getCanonicalName(), t);
            }
        }
    }

    private void validateMethod(Method method) {
        Class<?>[] parameterTypes = method.getParameterTypes();
        if (parameterTypes.length != 1) {
            throw new IllegalGameListenerMethodException(method, "Method " + method.getName() + " in type "
                    + method.getDeclaringClass().getCanonicalName() + " has more or less than 1 parameter");
        }

        Class<?> parameterType = parameterTypes[0];
        if (!Event.class.isAssignableFrom(parameterType)) {
            throw new IllegalGameListenerMethodException(method, "First parameter of method " + method.getName()
                    + " in type " + method.getDeclaringClass().getCanonicalName() + " is not a subtype of Event");
        }
    }

}