org.eclipse.jgit/src/org/eclipse/jgit/lib/BitmapIndex.java

/*
 * Copyright (C) 2012, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
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 * without modification, are permitted provided that the following
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 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
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 *   disclaimer in the documentation and/or other materials provided
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package org.eclipse.jgit.lib;

import java.util.Iterator;

import org.eclipse.jgit.internal.storage.file.PackBitmapIndex;

/**
 * A compressed bitmap representation of the entire object graph.
 *
 * @since 3.0
 */
public interface BitmapIndex {
	/**
	 * Get the bitmap for the id. The returned bitmap is immutable and the
	 * bitwise operations return the result of the operation in a new Bitmap.
	 *
	 * @param objectId
	 *            the object ID
	 * @return the Bitmap for the objectId or null, if one does not exist.
	 */
	Bitmap getBitmap(AnyObjectId objectId);

	/** @return a new {@code BitmapBuilder} based on the values in the index. */
	BitmapBuilder newBitmapBuilder();

	/**
	 * A bitmap representation of ObjectIds that can be iterated to return the
	 * underlying {@code ObjectId}s or operated on with other {@code Bitmap}s.
	 */
	public interface Bitmap extends Iterable<BitmapObject> {
		/**
		 * Bitwise-OR the current bitmap with the value from the other
		 * bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return a bitmap that is the bitwise-OR.
		 */
		Bitmap or(Bitmap other);

		/**
		 * Bitwise-AND-NOT the current bitmap with the value from the other
		 * bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return a bitmap that is the bitwise-AND-NOT.
		 */
		Bitmap andNot(Bitmap other);

		/**
		 * Bitwise-XOR the current bitmap with the value from the other
		 * bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return a bitmap that is the bitwise-XOR.
		 */
		Bitmap xor(Bitmap other);

		/**
		 * Returns an iterator over a set of elements of type BitmapObject. The
		 * BitmapObject instance is reused across calls to
		 * {@link Iterator#next()} for performance reasons.
		 *
		 * @return an Iterator.
		 */
		Iterator<BitmapObject> iterator();
	}

	/**
	 * A builder for a bitmap. The bitwise operations update the builder and
	 * return a reference to the current builder.
	 */
	public interface BitmapBuilder extends Bitmap {
		/**
		 * Adds the id and the existing bitmap for the id, if one exists, to the
		 * bitmap.
		 *
		 * @param objectId
		 *            the object ID
		 * @param type
		 *            the Git object type. See {@link Constants}.
		 * @return true if the value was not contained or able to be loaded.
		 */
		boolean add(AnyObjectId objectId, int type);

		/**
		 * Whether the bitmap has the id set.
		 *
		 * @param objectId
		 *            the object ID
		 * @return whether the bitmap currently contains the object ID
		 */
		boolean contains(AnyObjectId objectId);

		/**
		 * Remove the id from the bitmap.
		 *
		 * @param objectId
		 *            the object ID
		 */
		void remove(AnyObjectId objectId);

		/**
		 * Bitwise-OR the current bitmap with the value from the other bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return the current builder.
		 */
		BitmapBuilder or(Bitmap other);

		/**
		 * Bitwise-AND-NOT the current bitmap with the value from the other
		 * bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return the current builder.
		 */
		BitmapBuilder andNot(Bitmap other);

		/**
		 * Bitwise-XOR the current bitmap with the value from the other bitmap.
		 *
		 * @param other
		 *            the other bitmap
		 * @return the current builder.
		 */
		BitmapBuilder xor(Bitmap other);

		/** @return the fully built immutable bitmap */
		Bitmap build();

		/**
		 * Determines if the entire bitmap index is contained in the bitmap. If
		 * it is, the matching bits are removed from the bitmap and true is
		 * returned. If the bitmap index is null, false is returned.
		 *
		 * @param bitmapIndex
		 *            the bitmap index to check if it is completely contained
		 *            inside of the current bitmap.
		 * @return {@code true} if the bitmap index was a complete match.
		 */
		boolean removeAllOrNone(PackBitmapIndex bitmapIndex);

		/** @return the number of elements in the bitmap. */
		int cardinality();
	}
}