org.eclipse.jgit.lib.SymbolicRef.java Source code

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Here is the source code for org.eclipse.jgit.lib.SymbolicRef.java

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/*
 * Copyright (C) 2010, Google Inc.
 * 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.lib;

import org.eclipse.jgit.annotations.NonNull;
import org.eclipse.jgit.annotations.Nullable;

/**
 * A reference that indirectly points at another
 * {@link org.eclipse.jgit.lib.Ref}.
 * <p>
 * A symbolic reference always derives its current value from the target
 * reference.
 */
public class SymbolicRef implements Ref {
    private final String name;

    private final Ref target;

    private final long updateIndex;

    /**
     * Create a new ref pairing.
     *
     * @param refName
     *            name of this ref.
     * @param target
     *            the ref we reference and derive our value from.
     */
    public SymbolicRef(@NonNull String refName, @NonNull Ref target) {
        this.name = refName;
        this.target = target;
        this.updateIndex = UNDEFINED_UPDATE_INDEX;
    }

    /**
     * Create a new ref pairing.
     *
     * @param refName
     *            name of this ref.
     * @param target
     *            the ref we reference and derive our value from.
     * @param updateIndex
     *            index that increases with each update of the reference
     * @since 5.3
     */
    public SymbolicRef(@NonNull String refName, @NonNull Ref target, long updateIndex) {
        this.name = refName;
        this.target = target;
        this.updateIndex = updateIndex;
    }

    /** {@inheritDoc} */
    @Override
    @NonNull
    public String getName() {
        return name;
    }

    /** {@inheritDoc} */
    @Override
    public boolean isSymbolic() {
        return true;
    }

    /** {@inheritDoc} */
    @Override
    @NonNull
    public Ref getLeaf() {
        Ref dst = getTarget();
        while (dst.isSymbolic())
            dst = dst.getTarget();
        return dst;
    }

    /** {@inheritDoc} */
    @Override
    @NonNull
    public Ref getTarget() {
        return target;
    }

    /** {@inheritDoc} */
    @Override
    @Nullable
    public ObjectId getObjectId() {
        return getLeaf().getObjectId();
    }

    /** {@inheritDoc} */
    @Override
    @NonNull
    public Storage getStorage() {
        return Storage.LOOSE;
    }

    /** {@inheritDoc} */
    @Override
    @Nullable
    public ObjectId getPeeledObjectId() {
        return getLeaf().getPeeledObjectId();
    }

    /** {@inheritDoc} */
    @Override
    public boolean isPeeled() {
        return getLeaf().isPeeled();
    }

    /**
     * {@inheritDoc}
     * @since 5.3
     */
    @Override
    public long getUpdateIndex() {
        if (updateIndex == UNDEFINED_UPDATE_INDEX) {
            throw new UnsupportedOperationException();
        }
        return updateIndex;
    }

    /** {@inheritDoc} */
    @SuppressWarnings("nls")
    @Override
    public String toString() {
        StringBuilder r = new StringBuilder();
        r.append("SymbolicRef[");
        Ref cur = this;
        while (cur.isSymbolic()) {
            r.append(cur.getName());
            r.append(" -> ");
            cur = cur.getTarget();
        }
        r.append(cur.getName());
        r.append('=');
        r.append(ObjectId.toString(cur.getObjectId()));
        r.append("(");
        r.append(updateIndex); // Print value, even if -1
        r.append(")]");
        return r.toString();
    }
}