001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.util.stream.window;
031
032import java.util.ArrayList;
033
034import org.openimaj.util.function.Function;
035import org.openimaj.util.stream.AbstractStream;
036import org.openimaj.util.stream.Stream;
037
038/**
039 * Given a period of time to wait in milliseconds, this function consumes
040 * a stream for that period of time and produces a new stream of lists representing windows of that time period
041 * @author Sina Samangooei (ss@ecs.soton.ac.uk)
042 *
043 * @param <IN>
044 */
045public class RealTimeWindowFunction<IN> implements Function<Stream<IN>,Stream<Window<IN,Long>>>{
046
047        private long waitTime;
048
049        private long currentWindowStartTime;
050        /**
051         * @param waitTime
052         */
053        public RealTimeWindowFunction(long waitTime) {
054                this.waitTime = waitTime;
055                this.currentWindowStartTime = -1;
056        }
057
058        @Override
059        public Stream<Window<IN,Long>> apply(final Stream<IN> inner) {
060
061                return new AbstractStream<Window<IN,Long>>() {
062
063                        @Override
064                        public boolean hasNext() {
065                                return inner.hasNext();
066                        }
067                        @Override
068                        public Window<IN,Long> next() {
069                                currentWindowStartTime = System.currentTimeMillis();
070                                final ArrayList<IN> currentWindow = new ArrayList<IN>();
071                                while(inner.hasNext()){
072                                        if(System.currentTimeMillis() - currentWindowStartTime >= RealTimeWindowFunction.this.waitTime ){
073                                                break;
074                                        }
075                                        IN next = inner.next();
076                                        currentWindow.add(next);
077                                }
078
079//                              RealTimeWindowFunction.this.currentWindowStartTime = System.currentTimeMillis();
080                                return new Window<IN,Long>(currentWindowStartTime, currentWindow);
081                        }
082                };
083        }
084
085}