/* BloomFilter** $Id: BloomFilter.java 3655 2005-07-05 19:20:03Z gojomo $** Created on Jun 30, 2005** Copyright (C) 2005 Internet Archive; an adaptation of* LGPL work (C) Sebastiano Vigna** This file is part of the Heritrix web crawler (crawler.archive.org).** Heritrix is free software; you can redistribute it and/or modify* it under the terms of the GNU Lesser Public License as published by* the Free Software Foundation; either version 2.1 of the License, or* any later version.** Heritrix 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 Public License for more details.** You should have received a copy of the GNU Lesser Public License* along with Heritrix; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA*/package org.archive.util;/** * Common interface for different Bloom filter  * implementations *  * @author Gordon Mohr */public interface BloomFilter {	/** The number of character sequences in the filter.	 *	 * @return the number of character sequences in the filter (but see {@link #contains(CharSequence)}).	 */	public abstract int size();	/** Checks whether the given character sequence is in this filter.	 *	 * <P>Note that this method may return true on a character sequence that is has	 * not been added to the filter. This will happen with probability 2<sub>-<var>d</var></sub>,	 * where <var>d</var> is the number of hash functions specified at creation time, if	 * the number of the elements in the filter is less than <var>n</var>, the number	 * of expected elements specified at creation time.	 *	 * @param s a character sequence.	 * @return true if the sequence is in the filter (or if a sequence with the	 * same hash sequence is in the filter).	 */	public abstract boolean contains(final CharSequence s);	/** Adds a character sequence to the filter.	 *	 * @param s a character sequence.	 * @return true if the character sequence was not in the filter (but see {@link #contains(CharSequence)}).	 */	public abstract boolean add(final CharSequence s);	/**     * The amount of memory in bytes consumed by the bloom      * bitfield.     *	 * @return memory used by bloom bitfield, in bytes	 */	public abstract long getSizeBytes();}