src/main/java/com/sleepycat/collections/StoredSortedKeySet.java

/*-
 * Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
 *
 * This file was distributed by Oracle as part of a version of Oracle Berkeley
 * DB Java Edition made available at:
 *
 * http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
 *
 * Please see the LICENSE file included in the top-level directory of the
 * appropriate version of Oracle Berkeley DB Java Edition for a copy of the
 * license and additional information.
 */

package com.sleepycat.collections;

import java.util.Comparator;
import java.util.SortedSet;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.je.Database;
/* <!-- begin JE only --> */
import com.sleepycat.je.EnvironmentFailureException; // for javadoc
import com.sleepycat.je.OperationFailureException; // for javadoc
/* <!-- end JE only --> */
import com.sleepycat.util.RuntimeExceptionWrapper;

/**
 * The SortedSet returned by Map.keySet() and which can also be constructed
 * directly if a Map is not needed.
 * Since this collection is a set it only contains one element for each key,
 * even when duplicates are allowed.  Key set iterators are therefore
 * particularly useful for enumerating the unique keys of a store or index that
 * allows duplicates.
 *
 * <p>In addition to the standard SortedSet methods, this class provides the
 * following methods for stored sorted sets only.  Note that the use of these
 * methods is not compatible with the standard Java collections interface.</p>
 * <ul>
 * <li>{@link #headSet(Object, boolean)}</li>
 * <li>{@link #tailSet(Object, boolean)}</li>
 * <li>{@link #subSet(Object, boolean, Object, boolean)}</li>
 * </ul>
 *
 * @author Mark Hayes
 */
public class StoredSortedKeySet<K>
    extends StoredKeySet<K>
    implements SortedSet<K> {

    /**
     * Creates a sorted key set view of a {@link Database}.
     *
     * @param database is the Database underlying the new collection.
     *
     * @param keyBinding is the binding used to translate between key buffers
     * and key objects.
     *
     * @param writeAllowed is true to create a read-write collection or false
     * to create a read-only collection.
     *
     * @throws IllegalArgumentException if formats are not consistently
     * defined or a parameter is invalid.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public StoredSortedKeySet(Database database,
                              EntryBinding<K> keyBinding,
                              boolean writeAllowed) {

        super(new DataView(database, keyBinding, null, null,
                           writeAllowed, null));
    }

    StoredSortedKeySet(DataView keySetView) {

        super(keySetView);
    }

    /**
     * Returns null since comparators are not supported.  The natural ordering
     * of a stored collection is data byte order, whether the data classes
     * implement the {@link java.lang.Comparable} interface or not.
     * This method does not conform to the {@link SortedSet#comparator}
     * interface.
     *
     * @return null.
     */
    public Comparator<? super K> comparator() {

        return null;
    }

    /**
     * Returns the first (lowest) element currently in this sorted set.
     * This method conforms to the {@link SortedSet#first} interface.
     *
     * @return the first element.
     *
     * <!-- begin JE only -->
     * @throws OperationFailureException if one of the <a
     * href="../je/OperationFailureException.html#readFailures">Read Operation
     * Failures</a> occurs.
     *
     * @throws EnvironmentFailureException if an unexpected, internal or
     * environment-wide failure occurs.
     * <!-- end JE only -->
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public K first() {

        return getFirstOrLast(true);
    }

    /**
     * Returns the last (highest) element currently in this sorted set.
     * This method conforms to the {@link SortedSet#last} interface.
     *
     * @return the last element.
     *
     * <!-- begin JE only -->
     * @throws OperationFailureException if one of the <a
     * href="../je/OperationFailureException.html#readFailures">Read Operation
     * Failures</a> occurs.
     *
     * @throws EnvironmentFailureException if an unexpected, internal or
     * environment-wide failure occurs.
     * <!-- end JE only -->
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public K last() {

        return getFirstOrLast(false);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements are
     * strictly less than toKey.
     * This method conforms to the {@link SortedSet#headSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param toKey is the upper bound.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> headSet(K toKey) {

        return subSet(null, false, toKey, false);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements are
     * strictly less than toKey, optionally including toKey.
     * This method does not exist in the standard {@link SortedSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param toKey is the upper bound.
     *
     * @param toInclusive is true to include toKey.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> headSet(K toKey, boolean toInclusive) {

        return subSet(null, false, toKey, toInclusive);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements are
     * greater than or equal to fromKey.
     * This method conforms to the {@link SortedSet#tailSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param fromKey is the lower bound.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> tailSet(K fromKey) {

        return subSet(fromKey, true, null, false);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements are
     * strictly greater than fromKey, optionally including fromKey.
     * This method does not exist in the standard {@link SortedSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param fromKey is the lower bound.
     *
     * @param fromInclusive is true to include fromKey.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> tailSet(K fromKey, boolean fromInclusive) {

        return subSet(fromKey, fromInclusive, null, false);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements range
     * from fromKey, inclusive, to toKey, exclusive.
     * This method conforms to the {@link SortedSet#subSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param fromKey is the lower bound.
     *
     * @param toKey is the upper bound.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> subSet(K fromKey, K toKey) {

        return subSet(fromKey, true, toKey, false);
    }

    /**
     * Returns a view of the portion of this sorted set whose elements are
     * strictly greater than fromKey and strictly less than toKey,
     * optionally including fromKey and toKey.
     * This method does not exist in the standard {@link SortedSet} interface.
     *
     * <p>Note that the return value is a StoredCollection and must be treated
     * as such; for example, its iterators must be explicitly closed.</p>
     *
     * @param fromKey is the lower bound.
     *
     * @param fromInclusive is true to include fromKey.
     *
     * @param toKey is the upper bound.
     *
     * @param toInclusive is true to include toKey.
     *
     * @return the subset.
     *
     * @throws RuntimeExceptionWrapper if a checked exception is thrown,
     * including a {@code DatabaseException} on BDB (C edition).
     */
    public SortedSet<K> subSet(K fromKey,
                               boolean fromInclusive,
                               K toKey,
                               boolean toInclusive) {
        try {
            return new StoredSortedKeySet(
               view.subView(fromKey, fromInclusive, toKey, toInclusive, null));
        } catch (Exception e) {
            throw StoredContainer.convertException(e);
        }
    }
}