FIFORevQueue.java

/*
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> 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.revwalk;

import java.io.IOException;

import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;

/**
 * A queue of commits in FIFO order.
 */
public class FIFORevQueue extends BlockRevQueue {
    private Block head;

    private Block tail;

    /** Create an empty FIFO queue. */
    public FIFORevQueue() {
        super(false);
    }

    FIFORevQueue(boolean firstParent) {
        super(firstParent);
    }

    FIFORevQueue(Generator s) throws MissingObjectException,
            IncorrectObjectTypeException, IOException {
        super(s);
    }

    /** {@inheritDoc} */
    @Override
    public void add(RevCommit c) {
        Block b = tail;
        if (b == null) {
            b = free.newBlock();
            b.add(c);
            head = b;
            tail = b;
            return;
        } else if (b.isFull()) {
            b = free.newBlock();
            tail.next = b;
            tail = b;
        }
        b.add(c);
    }

    /**
     * Insert the commit pointer at the front of the queue.
     *
     * @param c
     *            the commit to insert into the queue.
     */
    public void unpop(RevCommit c) {
        Block b = head;
        if (b == null) {
            b = free.newBlock();
            b.resetToMiddle();
            b.add(c);
            head = b;
            tail = b;
            return;
        } else if (b.canUnpop()) {
            b.unpop(c);
            return;
        }

        b = free.newBlock();
        b.resetToEnd();
        b.unpop(c);
        b.next = head;
        head = b;
    }

    /** {@inheritDoc} */
    @Override
    public RevCommit next() {
        final Block b = head;
        if (b == null)
            return null;

        final RevCommit c = b.pop();
        if (b.isEmpty()) {
            head = b.next;
            if (head == null)
                tail = null;
            free.freeBlock(b);
        }
        return c;
    }

    /** {@inheritDoc} */
    @Override
    public void clear() {
        head = null;
        tail = null;
        free.clear();
    }

    @Override
    boolean everbodyHasFlag(int f) {
        for (Block b = head; b != null; b = b.next) {
            for (int i = b.headIndex; i < b.tailIndex; i++)
                if ((b.commits[i].flags & f) == 0)
                    return false;
        }
        return true;
    }

    @Override
    boolean anybodyHasFlag(int f) {
        for (Block b = head; b != null; b = b.next) {
            for (int i = b.headIndex; i < b.tailIndex; i++)
                if ((b.commits[i].flags & f) != 0)
                    return true;
        }
        return false;
    }

    void removeFlag(int f) {
        final int not_f = ~f;
        for (Block b = head; b != null; b = b.next) {
            for (int i = b.headIndex; i < b.tailIndex; i++)
                b.commits[i].flags &= not_f;
        }
    }

    /** {@inheritDoc} */
    @Override
    public String toString() {
        final StringBuilder s = new StringBuilder();
        for (Block q = head; q != null; q = q.next) {
            for (int i = q.headIndex; i < q.tailIndex; i++)
                describe(s, q.commits[i]);
        }
        return s.toString();
    }
}