package it.unimi.dsi.compression;
/*
* DSI utilities
*
* Copyright (C) 2005-2009 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.bits.BitVector;
/** A coder based on a set of prefix-free codewords.
*
* <P>Not all coders are codeword-based (for instance, arithmetic coding
* is not codeword-based). However, coders that are based on prefix-free codewords are invited
* to return by means of {@link it.unimi.dsi.compression.Codec#coder()} an
* implementation of this interface.
*
* <p>Note that the {@linkplain PrefixCodec#coder() coder} returned by a {@link PrefixCodec} is
* an implementation of this interface.
*/
public interface PrefixCoder extends Coder {
/** Provides access to the codewords.
*
* <strong>Warning</strong>: bit 0 of each bit vector returned by {@link #codeWords()} is
* the <em>first (leftmost) bit</em> of the corresponding codeword: in other words, codewords are stored in
* right-to-left fashion.
*
* @return the codewords.
*/
BitVector[] codeWords();
}