/*
* 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
*
* http://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.
*/
package org.apache.directory.server.xdbm;
import org.apache.directory.server.i18n.I18n;
import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException;
/**
* A Cursor over a single element.
*
* @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
* @version $Rev$, $Date$
*/
public class SingletonIndexCursor<K, E, ID> extends AbstractIndexCursor<K, E, ID>
{
private boolean beforeFirst = true;
private boolean afterLast;
private boolean onSingleton;
private final IndexEntry<K, E, ID> singleton;
public SingletonIndexCursor( IndexEntry<K, E, ID> singleton )
{
this.singleton = singleton;
}
public boolean available()
{
return onSingleton;
}
public void before( IndexEntry<K, E, ID> element ) throws Exception
{
throw new UnsupportedOperationException();
}
public void beforeValue( ID id, K value ) throws Exception
{
throw new UnsupportedOperationException();
}
public void afterValue( ID id, K value ) throws Exception
{
throw new UnsupportedOperationException();
}
public void after( IndexEntry<K, E, ID> element ) throws Exception
{
throw new UnsupportedOperationException();
}
public void beforeFirst() throws Exception
{
checkNotClosed( "()" );
beforeFirst = true;
afterLast = false;
onSingleton = false;
}
public void afterLast() throws Exception
{
checkNotClosed( "()" );
beforeFirst = false;
afterLast = true;
onSingleton = false;
}
public boolean first() throws Exception
{
checkNotClosed( "()" );
beforeFirst = false;
onSingleton = true;
afterLast = false;
return true;
}
public boolean last() throws Exception
{
checkNotClosed( "()" );
beforeFirst = false;
onSingleton = true;
afterLast = false;
return true;
}
public boolean isFirst() throws Exception
{
checkNotClosed( "()" );
return onSingleton;
}
public boolean isLast() throws Exception
{
checkNotClosed( "()" );
return onSingleton;
}
public boolean isAfterLast() throws Exception
{
checkNotClosed( "()" );
return afterLast;
}
public boolean isBeforeFirst() throws Exception
{
checkNotClosed( "()" );
return beforeFirst;
}
public boolean previous() throws Exception
{
checkNotClosed( "()" );
if ( beforeFirst )
{
return false;
}
if ( afterLast )
{
beforeFirst = false;
onSingleton = true;
afterLast = false;
return true;
}
// must be on the singleton
beforeFirst = true;
onSingleton = false;
afterLast = false;
return false;
}
public boolean next() throws Exception
{
checkNotClosed( "()" );
if ( beforeFirst )
{
beforeFirst = false;
onSingleton = true;
afterLast = false;
return true;
}
if ( afterLast )
{
return false;
}
// must be on the singleton
beforeFirst = false;
onSingleton = false;
afterLast = true;
return false;
}
public IndexEntry<K, E, ID> get() throws Exception
{
checkNotClosed( "()" );
if ( onSingleton )
{
return singleton;
}
if ( beforeFirst )
{
throw new InvalidCursorPositionException( I18n.err( I18n.ERR_705 ) );
}
else
{
throw new InvalidCursorPositionException( I18n.err( I18n.ERR_706 ) );
}
}
public boolean isElementReused()
{
return true;
}
}