/*
    * Copyright (C) 2017, Google Inc. 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
    * https://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.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 {@code bitmap} as a side
   * effect.
   * <p>
   * When the walk hits a commit that 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 AddToBitmapFilter extends RevFilter {
  	private final BitmapBuilder bitmap;
  
  	/**
  	 * Create a filter that adds visited commits to the given bitmap.
  	 *
  	 * @param bitmap bitmap to write visited commits to
  	 */
  	public AddToBitmapFilter(BitmapBuilder bitmap) {
  		this.bitmap = bitmap;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public final boolean include(RevWalk walker, RevCommit cmit) {
  		Bitmap visitedBitmap;
  
  		if (bitmap.contains(cmit)) {
  			// already included
  		} else if ((visitedBitmap = bitmap.getBitmapIndex()
  				.getBitmap(cmit)) != null) {
  			bitmap.or(visitedBitmap);
  		} else {
  			bitmap.addObject(cmit, Constants.OBJ_COMMIT);
  			return true;
  		}
  
  		for (RevCommit p : cmit.getParents()) {
  			p.add(RevFlag.SEEN);
  		}
  		return false;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public final RevFilter clone() {
  		throw new UnsupportedOperationException();
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public final boolean requiresCommitBody() {
  		return false;
  	}
  }