oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/version/VersionSelector.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.jackrabbit.oak.plugins.version;

import javax.jcr.RepositoryException;

import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * <i>Inspired by Jackrabbit 2.x</i>
 * <p>
 * This Interface defines the version selector that needs to provide a version,
 * given some hints and a version history. the selector is used in the various
 * restore methods in order to select the correct version of previously versioned
 * OPV=Version children upon restore. JSR170 states: <em>"This determination
 * [of the version] depends on the configuration of the workspace and is outside
 * the scope of this specification."</em>
 * <p>
 * The version selection in jackrabbit works as follows:<br>
 * The {@code Node.restore()} methods uses the
 * {@link DateVersionSelector} which is initialized with the creation date of
 * the parent version. This selector selects the latest version that is equal
 * or older than the given date. if no such version exists, the initial one
 * is restored.<br>
 * <p>
 *
 * @see DateVersionSelector
 * @see javax.jcr.version.VersionManager#restore
 */
interface VersionSelector {

    /**
     * Selects a version of the given version history. If this VersionSelector
     * is unable to select one, it can return {@code null}. Please note,
     * that a version selector is not allowed to return the root version.
     *
     * @param versionHistory version history to select a version from
     * @return A version or {@code null}.
     * @throws RepositoryException if an error occurs.
     */
    @Nullable
    NodeBuilder select(@NotNull NodeBuilder versionHistory) throws RepositoryException;
}