codewordcoder.java

MG4J (Managing Gigabytes for Java) is a free full-text search engine for large document collections

package it.unimi.dsi.mg4j.compression;

/*		 
* MG4J: Managing Gigabytes for Java
*
* Copyright (C) 2005-2007 Sebastiano Vigna 
*
*  This library is free software; you can redistribute it and/or modify it
*  under the terms of the GNU Lesser General Public License as published by the Free
*  Software Foundation; either version 2.1 of the License, or (at your option)
*  any later version.
*
*  This library 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 Lesser General Public License
*  for more details.
*
*  You should have received a copy of the GNU Lesser 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.
*
*/

import it.unimi.dsi.fastutil.booleans.BooleanIterator;
import it.unimi.dsi.fastutil.booleans.BooleanIterators;
import it.unimi.dsi.io.OutputBitStream;
import it.unimi.dsi.mg4j.util.BitVectorBooleanIterator;

import java.io.IOException;
import java.io.Serializable;

import cern.colt.bitvector.BitVector;

/** A coder based on a set of codewords. 
 * 
 * @deprecated Moved to <code>dsiutils</code>.
 */

@Deprecated
public class CodeWordCoder implements PrefixCoder, Serializable {
	private static final long serialVersionUID = 1L;
	/** The array of codewords of this coder. */
	protected final BitVector[] codeWord;
	
	/** Creates a new codeword-based coder using the given vector of codewords. The
	 * coder will be able to encode symbols numbered from 0 to <code>codeWord.length-1</code>, included.
	 * 
	 * @param codeWord a vector of coderwords.
	 */
	public CodeWordCoder( final BitVector[] codeWord ) {
		this.codeWord = codeWord;
	}

	public BooleanIterator encode( final int symbol ) {
		return new BitVectorBooleanIterator( codeWord[ symbol ] );
	}
	
	public int encode( final int symbol, final OutputBitStream obs ) throws IOException {
		final BitVector w = codeWord[ symbol ];
		final int size = w.size();
		for( int i = 0; i < size; i++ ) obs.writeBit( w.get( i ) );
		return size;
	}

	public int flush( final OutputBitStream unused ) { return 0; }

	public BooleanIterator flush() { return BooleanIterators.EMPTY_ITERATOR; }
	
	public BitVector[] codeWords() { return codeWord; }
}