001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *  http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.directory.api.ldap.model.cursor;
020
021
022import org.apache.directory.api.i18n.I18n;
023import org.apache.directory.api.ldap.model.constants.Loggers;
024import org.apache.directory.api.ldap.model.exception.LdapException;
025import org.slf4j.Logger;
026import org.slf4j.LoggerFactory;
027
028
029/**
030 * An empty Cursor implementation.
031 *
032 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
033 * @param <E> The type of element on which this cursor will iterate
034 */
035public class EmptyCursor<E> extends AbstractCursor<E>
036{
037    /** A dedicated log for cursors */
038    private static final Logger LOG_CURSOR = LoggerFactory.getLogger( Loggers.CURSOR_LOG.getName() );
039
040    /** Speedup for logs */
041    private static final boolean IS_DEBUG = LOG_CURSOR.isDebugEnabled();
042
043
044    public EmptyCursor()
045    {
046        if ( IS_DEBUG )
047        {
048            LOG_CURSOR.debug( "Creating EmptyCursor : {}", this );
049        }
050    }
051
052
053    /**
054     * {@inheritDoc}
055     */
056    public boolean available()
057    {
058        return false;
059    }
060
061
062    /**
063     * {@inheritDoc}
064     */
065    public void before( E element ) throws LdapException, CursorException
066    {
067        checkNotClosed( "before()" );
068    }
069
070
071    /**
072     * {@inheritDoc}
073     */
074    public void after( E element ) throws LdapException, CursorException
075    {
076        checkNotClosed( "after()" );
077    }
078
079
080    /**
081     * {@inheritDoc}
082     */
083    public void beforeFirst() throws LdapException, CursorException
084    {
085        checkNotClosed( "beforeFirst()" );
086    }
087
088
089    /**
090     * {@inheritDoc}
091     */
092    public void afterLast() throws LdapException, CursorException
093    {
094        checkNotClosed( "afterLast()" );
095    }
096
097
098    /**
099     * {@inheritDoc}
100     */
101    public boolean first() throws LdapException, CursorException
102    {
103        checkNotClosed( "first()" );
104        return false;
105    }
106
107
108    /**
109     * {@inheritDoc}
110     */
111    public boolean last() throws LdapException, CursorException
112    {
113        checkNotClosed( "last()" );
114        return false;
115    }
116
117
118    /**
119     * {@inheritDoc}
120     */
121    public boolean previous() throws LdapException, CursorException
122    {
123        checkNotClosed( "previous()" );
124        return false;
125    }
126
127
128    /**
129     * {@inheritDoc}
130     */
131    public boolean next() throws LdapException, CursorException
132    {
133        checkNotClosed( "next()" );
134        return false;
135    }
136
137
138    /**
139     * {@inheritDoc}
140     */
141    public E get() throws CursorException
142    {
143        checkNotClosed( "get()" );
144        throw new InvalidCursorPositionException( I18n.err( I18n.ERR_02004_EMPTY_CURSOR ) );
145    }
146
147
148    /**
149     * {@inheritDoc}
150     */
151    @Override
152    public void close()
153    {
154        if ( IS_DEBUG )
155        {
156            LOG_CURSOR.debug( "Closing EmptyCursor {}", this );
157        }
158
159        super.close();
160    }
161
162
163    /**
164     * {@inheritDoc}
165     */
166    @Override
167    public void close( Exception cause )
168    {
169        if ( IS_DEBUG )
170        {
171            LOG_CURSOR.debug( "Closing EmptyCursor {}", this );
172        }
173
174        super.close( cause );
175    }
176}