DirCacheBuildIterator.java

/*
 * Copyright (C) 2008-2009, Google Inc.
 * Copyright (C) 2009, Robin Rosenberg <robin.rosenberg@dewire.com>
 * 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.dircache;

import java.io.IOException;

import org.eclipse.jgit.errors.CorruptObjectException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.treewalk.AbstractTreeIterator;

/**
 * Iterate and update a {@link org.eclipse.jgit.dircache.DirCache} as part of a
 * <code>TreeWalk</code>.
 * <p>
 * Like {@link org.eclipse.jgit.dircache.DirCacheIterator} this iterator allows
 * a DirCache to be used in parallel with other sorts of iterators in a
 * TreeWalk. However any entry which appears in the source DirCache and which is
 * skipped by the TreeFilter is automatically copied into
 * {@link org.eclipse.jgit.dircache.DirCacheBuilder}, thus retaining it in the
 * newly updated index.
 * <p>
 * This iterator is suitable for update processes, or even a simple delete
 * algorithm. For example deleting a path:
 *
 * <pre>
 * final DirCache dirc = db.lockDirCache();
 * final DirCacheBuilder edit = dirc.builder();
 *
 * final TreeWalk walk = new TreeWalk(db);
 * walk.reset();
 * walk.setRecursive(true);
 * walk.setFilter(PathFilter.create(&quot;name/to/remove&quot;));
 * walk.addTree(new DirCacheBuildIterator(edit));
 *
 * while (walk.next())
 *  ; // do nothing on a match as we want to remove matches
 * edit.commit();
 * </pre>
 */
public class DirCacheBuildIterator extends DirCacheIterator {
    private final DirCacheBuilder builder;

    /**
     * Create a new iterator for an already loaded DirCache instance.
     * <p>
     * The iterator implementation may copy part of the cache's data during
     * construction, so the cache must be read in prior to creating the
     * iterator.
     *
     * @param dcb
     *            the cache builder for the cache to walk. The cache must be
     *            already loaded into memory.
     */
    public DirCacheBuildIterator(DirCacheBuilder dcb) {
        super(dcb.getDirCache());
        builder = dcb;
    }

    DirCacheBuildIterator(final DirCacheBuildIterator p,
            final DirCacheTree dct) {
        super(p, dct);
        builder = p.builder;
    }

    /** {@inheritDoc} */
    @Override
    public AbstractTreeIterator createSubtreeIterator(ObjectReader reader)
            throws IncorrectObjectTypeException, IOException {
        if (currentSubtree == null)
            throw new IncorrectObjectTypeException(getEntryObjectId(),
                    Constants.TYPE_TREE);
        return new DirCacheBuildIterator(this, currentSubtree);
    }

    /** {@inheritDoc} */
    @Override
    public void skip() throws CorruptObjectException {
        if (currentSubtree != null)
            builder.keep(ptr, currentSubtree.getEntrySpan());
        else
            builder.keep(ptr, 1);
        next(1);
    }

    /** {@inheritDoc} */
    @Override
    public void stopWalk() {
        final int cur = ptr;
        final int cnt = cache.getEntryCount();
        if (cur < cnt)
            builder.keep(cur, cnt - cur);
    }

    /** {@inheritDoc} */
    @Override
    protected boolean needsStopWalk() {
        return ptr < cache.getEntryCount();
    }
}