/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.btree.raba;
import java.util.Iterator;
/**
* Class with implementations supporting mutable and immutable variable length
* byte[] keys.
*
* @todo supporting a scalar int32 key natively would provide better performance
* for an object index. once it is up to int64, the byte[] approach could
* in fact be better on 32-bit hardware.
*
* @todo explore the use of sparse buffers that minimize copying for more
* efficient management of large #s of keys - how would search work for
* such buffers?
*
* @todo explore use of interpolated search. certainly we should be able to
* estimate the distribution of the keys when creating an immutable key
* buffer and choose binary vs interpolated vs linear search based on
* that.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public abstract class AbstractKeyBuffer implements IRaba {
/**
* Test the search key against the leading prefix shared by all bytes in the
* key buffer.
*
* @param prefixLength
* The length of the prefix shared by all keys in the buffer.
*
* @param searchKey
* The search key.
*
* @return Zero iff all bytes match and otherwise the insert position for
* the search key in the buffer. The insert position will be before
* the first key iff the search key is less than the prefix (-1) and
* will be after the last key iff the search key is greater than the
* prefix (-(nkeys)-1).
*/
abstract protected int _prefixMatchLength(final int prefixLength,
final byte[] searchKey);
/**
* Linear search.
*/
abstract protected int _linearSearch(final int searchKeyOffset, final byte[] searchKey);
/**
* Binary search.
*/
abstract protected int _binarySearch(final int searchKeyOffset, final byte[] searchKey);
@Override
public Iterator<byte[]> iterator() {
return new Iterator<byte[]>() {
int i = 0;
@Override
public boolean hasNext() {
return i < size();
}
@Override
public byte[] next() {
return get(i++);
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* Return the largest leading prefix shared by all keys.
*/
abstract public byte[] getPrefix();
/**
* The length of the leading prefix shared by all keys.
*/
abstract public int getPrefixLength();
}