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

/*
 * Copyright (C) 2008-2009, Google Inc.
 * Copyright (C) 2008, Jonas Fonseca <fonseca@diku.dk>
 * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
 * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org>
 * 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.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - 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
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.lib;


/**
 * Base class for a set of loaders for different representations of Git objects.
 * New loaders are constructed for every object.
 */
public abstract class ObjectLoader {
	/**
	 * @return Git in pack object type, see {@link Constants}.
	 */
	public abstract int getType();

	/**
	 * @return size of object in bytes
	 */
	public abstract long getSize();

	/**
	 * Obtain a copy of the bytes of this object.
	 * <p>
	 * Unlike {@link #getCachedBytes()} this method returns an array that might
	 * be modified by the caller.
	 *
	 * @return the bytes of this object.
	 */
	public final byte[] getBytes() {
		final byte[] data = getCachedBytes();
		final byte[] copy = new byte[data.length];
		System.arraycopy(data, 0, copy, 0, data.length);
		return copy;
	}

	/**
	 * Obtain a reference to the (possibly cached) bytes of this object.
	 * <p>
	 * This method offers direct access to the internal caches, potentially
	 * saving on data copies between the internal cache and higher level code.
	 * Callers who receive this reference <b>must not</b> modify its contents.
	 * Changes (if made) will affect the cache but not the repository itself.
	 *
	 * @return the cached bytes of this object. Do not modify it.
	 */
	public abstract byte[] getCachedBytes();

	/**
	 * @return raw object type from object header, as stored in storage (pack,
	 *         loose file). This may be different from {@link #getType()} result
	 *         for packs (see {@link Constants}).
	 */
	public abstract int getRawType();

	/**
	 * @return raw size of object from object header (pack, loose file).
	 *         Interpretation of this value depends on {@link #getRawType()}.
	 */
	public abstract long getRawSize();
}