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 java.io.IOException; 023 024import org.apache.directory.api.i18n.I18n; 025import org.apache.directory.api.ldap.model.constants.Loggers; 026import org.apache.directory.api.ldap.model.exception.LdapException; 027import org.slf4j.Logger; 028import org.slf4j.LoggerFactory; 029 030 031/** 032 * An empty Cursor implementation. 033 * 034 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 035 * @param <E> The type of element on which this cursor will iterate 036 */ 037public class EmptyCursor<E> extends AbstractCursor<E> 038{ 039 /** A dedicated log for cursors */ 040 private static final Logger LOG_CURSOR = LoggerFactory.getLogger( Loggers.CURSOR_LOG.getName() ); 041 042 /** Speedup for logs */ 043 private static final boolean IS_DEBUG = LOG_CURSOR.isDebugEnabled(); 044 045 046 /** 047 * Creates a new EmptyCursor instance 048 */ 049 public EmptyCursor() 050 { 051 if ( IS_DEBUG ) 052 { 053 LOG_CURSOR.debug( "Creating EmptyCursor : {}", this ); 054 } 055 } 056 057 058 /** 059 * {@inheritDoc} 060 */ 061 @Override 062 public boolean available() 063 { 064 return false; 065 } 066 067 068 /** 069 * {@inheritDoc} 070 */ 071 @Override 072 public void before( E element ) throws LdapException, CursorException 073 { 074 checkNotClosed( "before()" ); 075 } 076 077 078 /** 079 * {@inheritDoc} 080 */ 081 @Override 082 public void after( E element ) throws LdapException, CursorException 083 { 084 checkNotClosed( "after()" ); 085 } 086 087 088 /** 089 * {@inheritDoc} 090 */ 091 @Override 092 public void beforeFirst() throws LdapException, CursorException 093 { 094 checkNotClosed( "beforeFirst()" ); 095 } 096 097 098 /** 099 * {@inheritDoc} 100 */ 101 @Override 102 public void afterLast() throws LdapException, CursorException 103 { 104 checkNotClosed( "afterLast()" ); 105 } 106 107 108 /** 109 * {@inheritDoc} 110 */ 111 @Override 112 public boolean first() throws LdapException, CursorException 113 { 114 checkNotClosed( "first()" ); 115 return false; 116 } 117 118 119 /** 120 * {@inheritDoc} 121 */ 122 @Override 123 public boolean last() throws LdapException, CursorException 124 { 125 checkNotClosed( "last()" ); 126 return false; 127 } 128 129 130 /** 131 * {@inheritDoc} 132 */ 133 @Override 134 public boolean previous() throws LdapException, CursorException 135 { 136 checkNotClosed( "previous()" ); 137 return false; 138 } 139 140 141 /** 142 * {@inheritDoc} 143 */ 144 @Override 145 public boolean next() throws LdapException, CursorException 146 { 147 checkNotClosed( "next()" ); 148 return false; 149 } 150 151 152 /** 153 * {@inheritDoc} 154 */ 155 @Override 156 public E get() throws CursorException 157 { 158 checkNotClosed( "get()" ); 159 throw new InvalidCursorPositionException( I18n.err( I18n.ERR_02004_EMPTY_CURSOR ) ); 160 } 161 162 163 /** 164 * {@inheritDoc} 165 */ 166 @Override 167 public void close() throws IOException 168 { 169 if ( IS_DEBUG ) 170 { 171 LOG_CURSOR.debug( "Closing EmptyCursor {}", this ); 172 } 173 174 super.close(); 175 } 176 177 178 /** 179 * {@inheritDoc} 180 */ 181 @Override 182 public void close( Exception cause ) throws IOException 183 { 184 if ( IS_DEBUG ) 185 { 186 LOG_CURSOR.debug( "Closing EmptyCursor {}", this ); 187 } 188 189 super.close( cause ); 190 } 191}