/*
 * 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
 *
 *     https://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.
 */

/*
 * Sequence.java
 *
 */

package javax.jdo.datastore;

/**
 * Implementations of this interface can be used to obtain sequences. The behavior with regard to
 * the transaction and rollover behavior are defined in the metadata.
 *
 * @version 2.0
 * @since 2.0
 */
public interface Sequence {

  /**
   * Returns the fully qualified name of the <code>Sequence</code>.
   *
   * @return the name of the sequence
   */
  String getName();

  /**
   * Returns the next sequence value as an Object. If the next sequence value is not available,
   * throw JDODataStoreException.
   *
   * @return the next value
   */
  Object next();

  /**
   * Provides a hint to the implementation that the application will need <code>additional</code>
   * sequence value objects in short order. There is no externally visible behavior of this method.
   * It is used to potentially improve the efficiency of the algorithm of obtaining additional
   * sequence value objects.
   *
   * @param additional the number of additional values to allocate
   */
  void allocate(int additional);

  /**
   * Returns the current sequence value object if it is available. It is intended to return a
   * sequence value object previously used. If the current sequence value is not available, throw
   * JDODataStoreException.
   *
   * @return the current value
   */
  Object current();

  /**
   * Returns the next sequence value as a long. If the next sequence value is not available or is
   * not numeric, throw JDODataStoreException.
   *
   * @return the next value
   */
  long nextValue();

  /**
   * Returns the current sequence value as a long. If the current sequence value is not available or
   * is not numeric, throw JDODataStoreException.
   *
   * @return the current value
   */
  long currentValue();
}