/*
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
*/
/*
* Created on Aug 26, 2009
*/
package com.bigdata.btree.raba.codec;
import java.io.DataInput;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.OutputStream;
import java.util.Iterator;
import com.bigdata.btree.raba.AbstractRaba;
import com.bigdata.btree.raba.IRaba;
import com.bigdata.io.AbstractFixedByteArrayBuffer;
import com.bigdata.io.DataOutputBuffer;
/**
* Useful when a B+Tree uses keys but not values. The coder maintains the
* {@link IRaba#size()}, but any <code>byte[]</code> values stored under the
* B+Tree will be <strong>discarded</strong> by this {@link IRabaCoder}.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
public class EmptyRabaValueCoder implements IRabaCoder, Externalizable {
/**
*
*/
private static final long serialVersionUID = -8011456562258609162L;
@Override
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
// NOP
}
@Override
public void writeExternal(ObjectOutput out) throws IOException {
// NOP
}
public static transient final EmptyRabaValueCoder INSTANCE = new EmptyRabaValueCoder();
public EmptyRabaValueCoder() {
}
/**
* No. Keys can not be constrained to be empty.
*/
@Override
final public boolean isKeyCoder() {
return false;
}
/**
* Yes.
*/
@Override
final public boolean isValueCoder() {
return true;
}
@Override
public boolean isDuplicateKeys() {
return false;
}
@Override
public ICodedRaba encodeLive(final IRaba raba, final DataOutputBuffer buf) {
if (raba == null)
throw new IllegalArgumentException();
if (raba.isKeys()) {
// not allowed for B+Tree keys.
throw new UnsupportedOperationException();
}
final int O_origin = buf.pos();
final int size = raba.size();
buf.putInt(size);
return new EmptyCodedRaba(buf.slice(O_origin, buf.pos() - O_origin),
size);
}
/**
* <strong>Any data in the {@link IRaba} will be discarded!</strong> Only
* the {@link IRaba#size()} is maintained.
*/
@Override
public AbstractFixedByteArrayBuffer encode(final IRaba raba,
final DataOutputBuffer buf) {
if (raba == null)
throw new IllegalArgumentException();
if (raba.isKeys()) {
// not allowed for B+Tree keys.
throw new UnsupportedOperationException();
}
final int O_origin = buf.pos();
buf.putInt(raba.size());
return buf.slice(O_origin, buf.pos() - O_origin);
}
@Override
public ICodedRaba decode(final AbstractFixedByteArrayBuffer data) {
return new EmptyCodedRaba(data);
}
/**
* An {@link ICodedRaba} for use when the encoded logical byte[][] was
* empty.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan
* Thompson</a>
* @version $Id$
*/
static private class EmptyCodedRaba implements ICodedRaba {
private final AbstractFixedByteArrayBuffer data;
private final int size;
public EmptyCodedRaba(final AbstractFixedByteArrayBuffer data) {
if (data == null)
throw new IllegalArgumentException();
this.data = data;
size = data.getInt(0);
}
public EmptyCodedRaba(final AbstractFixedByteArrayBuffer data, final int size) {
if (data == null)
throw new IllegalArgumentException();
this.data = data;
this.size = size;
}
@Override
final public AbstractFixedByteArrayBuffer data() {
return data;
}
/**
* Yes.
*/
@Override
final public boolean isReadOnly() {
return true;
}
@Override
public boolean isKeys() {
return false;
}
@Override
final public int capacity() {
return size;
}
@Override
final public int size() {
return size;
}
@Override
final public boolean isEmpty() {
return size == 0;
}
@Override
final public boolean isFull() {
return true;
}
@Override
final public boolean isNull(final int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException();
return true;
}
@Override
final public int length(final int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException();
throw new NullPointerException();
}
@Override
final public byte[] get(final int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException();
return null;
}
@Override
final public int copy(final int index, final OutputStream os) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException();
throw new NullPointerException();
}
@Override
final public Iterator<byte[]> iterator() {
return new Iterator<byte[]>() {
int i = 0;
@Override
public boolean hasNext() {
return i < size;
}
@Override
public byte[] next() {
i++;
return null;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
/**
* If the {@link IRaba} represents B+Tree keys then returns <code>-1</code>
* as the insertion point.
*
* @throws UnsupportedOperationException
* unless the {@link IRaba} represents B+Tree keys.
*/
@Override
final public int search(final byte[] searchKey) {
if (isKeys())
return -1;
throw new UnsupportedOperationException();
}
/*
* Mutation API is not supported.
*/
@Override
final public int add(byte[] a) {
throw new UnsupportedOperationException();
}
@Override
final public int add(byte[] value, int off, int len) {
throw new UnsupportedOperationException();
}
@Override
final public int add(DataInput in, int len) throws IOException {
throw new UnsupportedOperationException();
}
@Override
final public void set(int index, byte[] a) {
throw new UnsupportedOperationException();
}
@Override
final public String toString() {
return AbstractRaba.toString(this);
}
}
}