001/*
002 * CDDL HEADER START
003 *
004 * The contents of this file are subject to the terms of the
005 * Common Development and Distribution License, Version 1.0 only
006 * (the "License").  You may not use this file except in compliance
007 * with the License.
008 *
009 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
010 * or http://forgerock.org/license/CDDLv1.0.html.
011 * See the License for the specific language governing permissions
012 * and limitations under the License.
013 *
014 * When distributing Covered Code, include this CDDL HEADER in each
015 * file and include the License file at legal-notices/CDDLv1_0.txt.
016 * If applicable, add the following below this CDDL HEADER, with the
017 * fields enclosed by brackets "[]" replaced with your own identifying
018 * information:
019 *      Portions Copyright [yyyy] [name of copyright owner]
020 *
021 * CDDL HEADER END
022 *
023 *
024 *      Copyright 2014-2015 ForgeRock AS
025 */
026package org.opends.server.backends.pluggable.spi;
027
028import java.io.Closeable;
029import java.util.NoSuchElementException;
030
031/**
032 * Cursor extended with navigation methods.
033 * @param <K> Type of the record's key
034 * @param <V> Type of the record's value
035 */
036public interface SequentialCursor<K,V> extends Closeable
037{
038  /**
039   * Moves this cursor to the next record in the tree.
040   *
041   * @return {@code true} if the cursor has moved to the next record,
042   *         {@code false} if no next record exists leaving cursor
043   *         in undefined state.
044   */
045  boolean next();
046
047  /**
048   * Check whether this cursor is currently pointing to valid record.
049   *
050   * @return {@code true} if the cursor is pointing to a valid entry,
051   *         {@code false} if cursor is not pointing to a valid entry
052   */
053  boolean isDefined();
054
055  /**
056   * Returns the key of the record on which this cursor is currently positioned.
057   *
058   * @return the current record's key.
059   * @throws NoSuchElementException if the cursor is not defined.
060   */
061  K getKey() throws NoSuchElementException;
062
063  /**
064   * Returns the value of the record on which this cursor is currently positioned.
065   *
066   * @return the current record's value.
067   * @throws NoSuchElementException if the cursor is not defined.
068   */
069  V getValue() throws NoSuchElementException;
070
071  /**
072   * Deletes the record on which this cursor is currently positioned. This method does not alter the position of the
073   * cursor. In particular, {@link #next()} must be called in order to point to the next record. The behavior of
074   * methods {@link #getKey()} and {@link #getValue()} after this method returns is undefined.
075   *
076   * @throws NoSuchElementException if the cursor is not defined.
077   * @throws UnsupportedOperationException if the cursor implementation does not support updates.
078   */
079  void delete() throws NoSuchElementException, UnsupportedOperationException;
080
081  /** {@inheritDoc} */
082  @Override
083  void close();
084}