src.it.unimi.dsi.compression.PrefixCoder Maven / Gradle / Ivy
/*
* DSI utilities
*
* Copyright (C) 2005-2023 Sebastiano Vigna
*
* This program and the accompanying materials are made available under the
* terms of the GNU Lesser General Public License v2.1 or later,
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html,
* or the Apache Software License 2.0, which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* 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.
*
* SPDX-License-Identifier: LGPL-2.1-or-later OR Apache-2.0
*/
package it.unimi.dsi.compression;
import it.unimi.dsi.bits.BitVector;
/** A coder based on a set of prefix-free codewords.
*
* 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.
*
*
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.
*
* Warning: bit 0 of each bit vector returned by {@link #codeWords()} is
* the first (leftmost) bit of the corresponding codeword: in other words, codewords are stored in
* right-to-left fashion.
*
* @return the codewords.
*/
BitVector[] codeWords();
}