62 lines
1.2 KiB
Java
62 lines
1.2 KiB
Java
package org.gcube.data.streams.delegates;
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import org.gcube.data.streams.Stream;
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/**
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* A {@link Stream} that notifies an {@link StreamListener} of key iteration events.
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*
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* @author Fabio Simeoni
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*
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* @param <E> the type of stream elements
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*/
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public class MonitoredStream<E> extends AbstractDelegateStream<E,E> {
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private final StreamListener listener;
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private boolean started=false;
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/**
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* Creates an instance with a {@link Stream} and a {@link StreamListener}.
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* @param stream the stream
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* @param listener the listener
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* @throws IllegalArgumentException if the stream or the listener are {@code null}
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*/
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public MonitoredStream(Stream<E> stream,StreamListener listener) throws IllegalArgumentException {
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super(stream);
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if (listener==null)
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throw new IllegalArgumentException("invalid null listener");
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this.listener=listener;
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}
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@Override
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protected E delegateNext() {
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E element = stream().next();
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if (!started) {
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listener.onStart();
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started=true;
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}
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if (!delegateHasNext())
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listener.onEnd();
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return element;
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}
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@Override
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protected boolean delegateHasNext() {
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return stream().hasNext();
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}
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@Override
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public void close() {
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super.close();
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listener.onClose();
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}
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}
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