org.eclipse.jgit.revwalk.RevObjectList Maven / Gradle / Ivy
/*
* Copyright (C) 2009, Google Inc.
* Copyright (C) 2009, Jonas Fonseca
* Copyright (C) 2008, Shawn O. Pearce
* 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;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.eclipse.jgit.revwalk;
import java.text.MessageFormat;
import java.util.AbstractList;
import org.eclipse.jgit.internal.JGitText;
/**
* An ordered list of {@link RevObject} subclasses.
*
* @param
* type of subclass of RevObject the list is storing.
*/
public class RevObjectList extends AbstractList {
static final int BLOCK_SHIFT = 8;
static final int BLOCK_SIZE = 1 << BLOCK_SHIFT;
/**
* Items stored in this list.
*
* If {@link Block#shift} = 0 this block holds the list elements; otherwise
* it holds pointers to other {@link Block} instances which use a shift that
* is {@link #BLOCK_SHIFT} smaller.
*/
protected Block contents = new Block(0);
/** Current number of elements in the list. */
protected int size = 0;
/** Create an empty object list. */
public RevObjectList() {
// Initialized above.
}
public void add(final int index, final E element) {
if (index != size)
throw new UnsupportedOperationException(MessageFormat.format(
JGitText.get().unsupportedOperationNotAddAtEnd,
Integer.valueOf(index)));
set(index, element);
size++;
}
public E set(int index, E element) {
Block s = contents;
while (index >> s.shift >= BLOCK_SIZE) {
s = new Block(s.shift + BLOCK_SHIFT);
s.contents[0] = contents;
contents = s;
}
while (s.shift > 0) {
final int i = index >> s.shift;
index -= i << s.shift;
if (s.contents[i] == null)
s.contents[i] = new Block(s.shift - BLOCK_SHIFT);
s = (Block) s.contents[i];
}
final Object old = s.contents[index];
s.contents[index] = element;
return (E) old;
}
public E get(int index) {
Block s = contents;
if (index >> s.shift >= 1024)
return null;
while (s != null && s.shift > 0) {
final int i = index >> s.shift;
index -= i << s.shift;
s = (Block) s.contents[i];
}
return s != null ? (E) s.contents[index] : null;
}
public int size() {
return size;
}
@Override
public void clear() {
contents = new Block(0);
size = 0;
}
/** One level of contents, either an intermediate level or a leaf level. */
protected static class Block {
final Object[] contents = new Object[BLOCK_SIZE];
final int shift;
Block(final int s) {
shift = s;
}
}
}