001/*
002 * GWTEventService
003 * Copyright (c) 2011 and beyond, strawbill UG (haftungsbeschr?nkt)
004 *
005 * This is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU Lesser General Public License as
007 * published by the Free Software Foundation; either version 3 of
008 * the License, or (at your option) any later version.
009 * Other licensing for GWTEventService may also be possible on request.
010 * Please view the license.txt of the project for more information.
011 *
012 * This software is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this software; if not, write to the Free
019 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021 */
022package de.novanic.eventservice.client.event.filter;
023
024import de.novanic.eventservice.client.event.Event;
025
026import java.util.Arrays;
027import java.util.List;
028import java.util.ArrayList;
029
030/**
031 * The DefaultCompositeEventFilter can handle various attached {@link de.novanic.eventservice.client.event.filter.EventFilter} instances.
032 * The match method calls all attached {@link de.novanic.eventservice.client.event.filter.EventFilter} instances to check if the
033 * {@link de.novanic.eventservice.client.event.Event} has to be filtered.
034 *
035 * @author sstrohschein
036 *         <br>Date: 04.03.2009
037 *         <br>Time: 20:56:07
038 */
039public class DefaultCompositeEventFilter implements CompositeEventFilter
040{
041    private List<EventFilter> myEventFilters;
042
043    /**
044     * Creates a new DefaultCompositeEventFilter. {@link de.novanic.eventservice.client.event.filter.EventFilter} instances
045     * must be attached with {@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)} or
046     * the constructor {@link de.novanic.eventservice.client.event.filter.DefaultCompositeEventFilter#DefaultCompositeEventFilter(EventFilter...)} must
047     * be used to register {@link de.novanic.eventservice.client.event.filter.EventFilter} instances for the match method.
048     */
049    public DefaultCompositeEventFilter() {
050        myEventFilters = new ArrayList<EventFilter>();
051    }
052
053    /**
054     * Creates a new DefaultCompositeEventFilter. The {@link de.novanic.eventservice.client.event.filter.EventFilter} instances
055     * are used by the match method to filter the events. More {@link de.novanic.eventservice.client.event.filter.EventFilter} instances
056     * can be attached with the attach method ({@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)}).
057     * @param anEventFilters {@link de.novanic.eventservice.client.event.filter.EventFilter} which are used by the match method
058     */
059    public DefaultCompositeEventFilter(EventFilter... anEventFilters) {
060        myEventFilters = new ArrayList<EventFilter>(Arrays.asList(anEventFilters));
061    }
062
063    /**
064     * If the match method returns true for an event, the event should be ignored, because the EventFilter recognizes
065     * the event to filter it. The DefaultCompositeEventFilter uses the attached {@link de.novanic.eventservice.client.event.filter.EventFilter}
066     * instances to filter the events. See {@link de.novanic.eventservice.client.event.filter.DefaultCompositeEventFilter#DefaultCompositeEventFilter(EventFilter...)}
067     * or {@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)} to append
068     * {@link de.novanic.eventservice.client.event.filter.EventFilter} instances.
069     * @param anEvent event to check
070     * @return true when the event should be filtered, otherwise false
071     */
072    public boolean match(Event anEvent) {
073        for(EventFilter theEventFilter: myEventFilters) {
074            if(theEventFilter.match(anEvent)) {
075                return true;
076            }
077        }
078        return false;
079    }
080
081    /**
082     * Appends another {@link de.novanic.eventservice.client.event.filter.EventFilter} which is used/called from the match method
083     * ({@link de.novanic.eventservice.client.event.filter.EventFilter#match(de.novanic.eventservice.client.event.Event)}).
084     * @param anEventFilter {@link de.novanic.eventservice.client.event.filter.EventFilter} to attach
085     * @return the created AppendableEventFilter (to attach more {@link de.novanic.eventservice.client.event.filter.EventFilter} instances)
086     */
087    public AppendableEventFilter attach(EventFilter anEventFilter) {
088        myEventFilters.add(anEventFilter);
089        return this;
090    }
091
092    /**
093     * Detaches the attached {@link de.novanic.eventservice.client.event.filter.EventFilter} instances.
094     * EventFilter instances can be attached with {@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)}.
095     * @return true if the EventFilter was removed with that call, otherwise false
096     */
097    public boolean detach(EventFilter anEventFilter) {
098        return myEventFilters.remove(anEventFilter);
099    }
100
101    /**
102     * Detaches all attached {@link de.novanic.eventservice.client.event.filter.EventFilter} instances.
103     * EventFilter instances can be attached with {@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)}.
104     * @return true if at least one EventFilter was removed with that call, otherwise false
105     */
106    public boolean detach() {
107        boolean isEmpty = myEventFilters.isEmpty();
108        myEventFilters.clear();
109        return !isEmpty;
110    }
111
112    /**
113     * Returns the attached EventFilters.
114     * EventFilter instances can be attached with {@link de.novanic.eventservice.client.event.filter.AppendableEventFilter#attach(EventFilter)}.
115     * @return the attached {@link de.novanic.eventservice.client.event.filter.EventFilter}
116     */
117    public List<EventFilter> getAttachedEventFilters() {
118        return myEventFilters;
119    }
120}