Class SeekableViewChain

src/core/SeekableViewChain.java:18–97

import java.util.NoSuchElementException;

public class SeekableViewChain implements SeekableView {

    private final List<SeekableView> iterators;
    private int currentIterator;

    SeekableViewChain(List<SeekableView> iterators) {
        this.iterators = iterators;
    }

    /**
     * Returns {@code true} if this view has more elements.
     */
    @Override
    public boolean hasNext() {
        SeekableView iterator = getCurrentIterator();
        return iterator != null && iterator.hasNext();
    }

    /**
     * Returns a <em>view</em> on the next data point.
     * No new object gets created, the referenced returned is always the same
     * and must not be stored since its internal data structure will change the
     * next time {@code next()} is called.
     *
     * @throws NoSuchElementException if there were no more elements to iterate
     *                                on (in which case {@link #hasNext} would have returned {@code false}.
     */
    @Override
    public DataPoint next() {
        SeekableView iterator = getCurrentIterator();
        if (iterator == null || !iterator.hasNext()) {
            throw new NoSuchElementException("No elements left in iterator");
        }

        DataPoint next = iterator.next();

        if (!iterator.hasNext()) {
            currentIterator++;
        }

        return next;
    }

    /**
     * Unsupported operation.
     *
     * @throws UnsupportedOperationException always.
     */
    @Override
    public void remove() {
        throw new UnsupportedOperationException("Removing items is not supported");
    }

    /**
     * Advances the iterator to the given point in time.
     * <p>
     * This allows the iterator to skip all the data points that are strictly
     * before the given timestamp.