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/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   * 	Redistributions of source code must retain the above copyright notice,
 * 	this list of conditions and the following disclaimer.
 *
 *   *	Redistributions in binary form must reproduce the above copyright notice,
 * 	this list of conditions and the following disclaimer in the documentation
 * 	and/or other materials provided with the distribution.
 *
 *   *	Neither the name of the University of Southampton nor the names of its
 * 	contributors may be used to endorse or promote products derived from this
 * 	software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.lsh.functions;

import org.openimaj.util.comparator.DistanceComparator;
import org.openimaj.util.hash.HashFunctionFactory;

import cern.jet.random.engine.MersenneTwister;

/**
 * A factory for producing {@link RandomisedHashFunction}s.
 * 
 * @author Jonathon Hare ([email protected])
 * 
 * @param 
 *            type of object being hashed
 */
public abstract class RandomisedHashFunctionFactory
		implements
			HashFunctionFactory
{
	protected MersenneTwister rng;
	protected int ndims;

	/**
	 * * @param ndims number of dimensions of data
	 * 
	 * @param rng
	 *            the random number generator
	 */
	protected RandomisedHashFunctionFactory(int ndims, MersenneTwister rng) {
		this.rng = rng;
		this.ndims = ndims;
	}

	/**
	 * @return a distance comparator that produces distances of the type
	 *         approximated by this hashing scheme
	 */
	public abstract DistanceComparator distanceFunction();
}