/*
 * Copyright (c) 2020, Google LLC  and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.internal.revwalk;

import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.revwalk.filter.RevFilter;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevFlag;

A RevFilter that adds the visited commits to bitmap as a side effect. 
 When the walk hits a commit that is the same as cachedCommit or is part of bitmap's BitmapIndex, that entire bitmap is ORed into bitmap and the commit and its parents are marked as SEEN so that the walk does not have to visit its ancestors. This ensures the walk is very short if there is good bitmap coverage. /**
 * A RevFilter that adds the visited commits to {@code bitmap} as a side effect.
 * <p>
 * When the walk hits a commit that is the same as {@code cachedCommit} or is
 * part of {@code bitmap}'s BitmapIndex, that entire bitmap is ORed into
 * {@code bitmap} and the commit and its parents are marked as SEEN so that the
 * walk does not have to visit its ancestors. This ensures the walk is very
 * short if there is good bitmap coverage.
 */
public class AddToBitmapWithCacheFilter extends RevFilter {
	private final AnyObjectId cachedCommit;

	private final Bitmap cachedBitmap;

	private final BitmapBuilder bitmap;

	
Create a filter with a cached BitmapCommit that adds visited commits to
the given bitmap.
Params:
cachedCommit – 
           the cached commit
cachedBitmap –  the bitmap corresponds to cachedCommit}
bitmap – 
           bitmap to write visited commits to/**
	 * Create a filter with a cached BitmapCommit that adds visited commits to
	 * the given bitmap.
	 *
	 * @param cachedCommit
	 *            the cached commit
	 * @param cachedBitmap
	 *            the bitmap corresponds to {@code cachedCommit}}
	 * @param bitmap
	 *            bitmap to write visited commits to
	 */
	public AddToBitmapWithCacheFilter(AnyObjectId cachedCommit,
			Bitmap cachedBitmap,
			BitmapBuilder bitmap) {
		this.cachedCommit = cachedCommit;
		this.cachedBitmap = cachedBitmap;
		this.bitmap = bitmap;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public final boolean include(RevWalk rw, RevCommit c) {
		Bitmap visitedBitmap;

		if (bitmap.contains(c)) {
			// already included
		} else if ((visitedBitmap = bitmap.getBitmapIndex()
				.getBitmap(c)) != null) {
			bitmap.or(visitedBitmap);
		} else if (cachedCommit.equals(c)) {
			bitmap.or(cachedBitmap);
		} else {
			bitmap.addObject(c, Constants.OBJ_COMMIT);
			return true;
		}

		for (RevCommit p : c.getParents()) {
			p.add(RevFlag.SEEN);
		}
		return false;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public final RevFilter clone() {
		throw new UnsupportedOperationException();
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public final boolean requiresCommitBody() {
		return false;
	}
}