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The DSI utilities are a mishmash of classes accumulated during the last twenty years in projects developed at the DSI (Dipartimento di Scienze dell'Informazione, i.e., Information Sciences Department), now DI (Dipartimento di Informatica, i.e., Informatics Department), of the Universita` degli Studi di Milano.

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package it.unimi.dsi.compression;

/*
 * DSI utilities
 *
 * Copyright (C) 2005-2018 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 3 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, see .
 *
 */

import it.unimi.dsi.fastutil.booleans.BooleanIterator;
import it.unimi.dsi.io.OutputBitStream;

import java.io.IOException;

/** Coding methods for a specific compression technique. */
public interface Coder {
	/** Encodes a symbol.
	 *
	 * @param symbol a symbol.
	 * @return a boolean iterator returning the bits coding symbol.
	 */
	BooleanIterator encode(int symbol);

	/** Encodes a symbol.
	 *
	 * @param symbol a symbol.
	 * @param obs the output bit stream where the encoded symbol will be written.
	 * @return the number of bits written.
	 */
	int encode(int symbol, OutputBitStream obs) throws IOException;

	/** Flushes the coder.
	 *
	 * Warning: this method will not {@link OutputBitStream#flush() flush} obs.
	 *
	 * @param obs the output bit stream where the flushing bits will be written.
	 * @return the number of bits written to flush the coder.
	 */

	int flush(OutputBitStream obs);

	/** Flushes the coder.
	 *
	 * @return a boolean iterator returning the bits used to flush this coder.
	 */

	BooleanIterator flush();
}