public final class EqualDelta<T> extends AbstractDelta<T>
{
	/**
	 * Creates an insert delta with the two given chunks.
	 *
	 * @param original The original chunk. Must not be {@code null}.
	 * @param revised  The original chunk. Must not be {@code null}.
	 */
	public EqualDelta(Chunk<T> original, Chunk<T> revised)
	{
		super(DeltaType.EQUAL, original, revised);
	}

	@Override
	public void applyTo(List<T> target) throws PatchFailedException
	{
		verifyChunk(target);
	}

	@Override
	public void restore(List<T> target)
	{
	}

	@Override
	public String toString()
	{
		return "[EqualDelta, source.position: " + getSource().getPosition() + ", target.position: " +
			getTarget().getPosition() + ", lines: " + getSource().getLines() + "]";
	}
}

/**
 * Adds EqualDelta entries (not added by DiffUtils.diff()).
 *
 * @param <T>    the type of elements in the lists
 * @param deltas the list of deltas
 * @param source the source list
 * @param target the target list
 * @return the updated list
 */
private <T> List<AbstractDelta<T>> addEqualDeltas(List<AbstractDelta<T>> deltas, List<T> source,
						  List<T> target)
{
	// WORKAROUND: https://github.com/java-diff-utils/java-diff-utils/issues/42
	List<AbstractDelta<T>> result = new ArrayList<>();
	int sourceStartPosition = 0;
	int targetStartPosition = 0;
	for (AbstractDelta<T> delta : deltas)
	{
		int sourceEndPosition = delta.getSource().getPosition();
		int targetEndPosition = delta.getTarget().getPosition();
		if (sourceStartPosition < sourceEndPosition || targetStartPosition < targetEndPosition)
		{
			// The gaps between deltas denote equal chunks
			result.add(new EqualDelta<>(
				new Chunk<>(sourceStartPosition, source.subList(sourceStartPosition, sourceEndPosition)),
				new Chunk<>(targetStartPosition, target.subList(targetStartPosition, targetEndPosition))));
		}
		sourceStartPosition = delta.getSource().last() + 1;
		targetStartPosition = delta.getTarget().last() + 1;
		result.add(delta);
	}
	// Add final chunk, if necessary.
	if (sourceStartPosition < source.size() || targetStartPosition < target.size())
	{
		// Deltas do not contain equal chunks. We need to derive those ourselves.
		result.add(new EqualDelta<>(
			new Chunk<>(sourceStartPosition, source.subList(sourceStartPosition, source.size())),
			new Chunk<>(targetStartPosition, target.subList(targetStartPosition, target.size()))));
	}
	return result;
}