QueueSourceUsage.java

/*
    BeepBeep, an event stream processor
    Copyright (C) 2008-2016 Sylvain Hallé

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package basic;

import ca.uqac.lif.cep.Pullable;
import ca.uqac.lif.cep.tmf.QueueSource;

/**
 * Pull events from the
 * {@link ca.uqac.lif.cep.tmf.QueueSource QueueSource} processor.
 * Graphically, the queue source is represented as follows:
 * <p>
 * <img src="./doc-files/basic/QueueSourceUsage.png" alt="Processor graph">
 * <p>
 * Since it is a <em>source</em>, it has no input streams. We represent
 * in a rectangle the queue of events that the source will dispense.
 * @author Sylvain Hallé
 * @difficulty Easy
 */
public class QueueSourceUsage
{
    public static void main(String[] args)
    {
        /// Create an empty queue source
        QueueSource source = new QueueSource();
        // Tell the source what events to output by giving it an array;
        // in this case, we output the first powers of 2
        source.setEvents(1, 2, 4, 8, 16, 32);
        // Get a pullable to the source
        Pullable p = source.getPullableOutput();
        // Pull 8 events from the source. The queue source loops through
        // its array of events; hence after reaching the last (32), it
        // will restart from the beginning of its list.
        for (int i = 0; i < 8; i++)
        {
            // Method pull() returns an Object, hence we must manually cast
            // it as an integer (this is indeed what we get)
            int x = (Integer) p.pull();
            System.out.println("The event is: " + x);
        }
        ///
    }
}