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///////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2002, Eric D. Friedman All Rights Reserved.
//
// 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 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.
///////////////////////////////////////////////////////////////////////////////

package gnu.trove.strategy;

import java.io.Serializable;


/**
 * Interface to support pluggable hashing strategies in maps and sets.
 * Implementers can use this interface to make the trove hashing
 * algorithms use object values, values provided by the java runtime,
 * or a custom strategy when computing hashcodes.
 *
 * @author Eric Friedman
 * @author Rob Eden
 */

public interface HashingStrategy extends Serializable {
	static final long serialVersionUID = 5674097166776615540L;

	/**
	 * Computes a hash code for the specified object.  Implementers
	 * can use the object's own hashCode method, the Java
	 * runtime's identityHashCode, or a custom scheme.
	 *
	 * @param object for which the hashcode is to be computed
	 * @return the hashCode
	 */
	int computeHashCode( T object );

	/**
	 * Compares o1 and o2 for equality.  Strategy implementers may use
	 * the objects' own equals() methods, compare object references,
	 * or implement some custom scheme.
	 *
	 * @param o1 an Object value
	 * @param o2 an Object value
	 * @return true if the objects are equal according to this strategy.
	 */
	boolean equals( T o1, T o2 );
}