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- /*
- * Copyright (C) 2009, Google Inc.
- * Copyright (C) 2009, Jonas Fonseca <fonseca@diku.dk>
- * Copyright (C) 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;
- * 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 <E>
- * type of subclass of RevObject the list is storing.
- */
- public class RevObjectList<E extends RevObject> extends AbstractList<E> {
- static final int BLOCK_SHIFT = 8;
-
- static final int BLOCK_SIZE = 1 << BLOCK_SHIFT;
-
- /**
- * Items stored in this list.
- * <p>
- * 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++;
- }
-
- @SuppressWarnings("unchecked")
- 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;
- }
-
- @SuppressWarnings("unchecked")
- 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;
- }
- }
- }
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