ch.bfh.unicrypt.helper.math.Point Maven / Gradle / Ivy

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/*
 * UniCrypt
 *
 *  UniCrypt(tm): Cryptographical framework allowing the implementation of cryptographic protocols e.g. e-voting
 *  Copyright (c) 2016 Bern University of Applied Sciences (BFH), Research Institute for
 *  Security in the Information Society (RISIS), E-Voting Group (EVG)
 *  Quellgasse 21, CH-2501 Biel, Switzerland
 *
 *  Licensed under Dual License consisting of:
 *  1. GNU Affero General Public License (AGPL) v3
 *  and
 *  2. Commercial license
 *
 *
 *  1. This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Affero General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   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.  See the
 *   GNU Affero General Public License for more details.
 *
 *   You should have received a copy of the GNU Affero General Public License
 *   along with this program.  If not, see .
 *
 *
 *  2. Licensees holding valid commercial licenses for UniCrypt may use this file in
 *   accordance with the commercial license agreement provided with the
 *   Software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and Bern University of Applied Sciences (BFH), Research Institute for
 *   Security in the Information Society (RISIS), E-Voting Group (EVG)
 *   Quellgasse 21, CH-2501 Biel, Switzerland.
 *
 *
 *   For further information contact 
 *
 *
 * Redistributions of files must retain the above copyright notice.
 */
package ch.bfh.unicrypt.helper.math;

import ch.bfh.unicrypt.UniCrypt;

/**
 * Instances of this generic class represent points {@code (x,y)} in a two-dimensional space over the generic type,
 * including a special point of infinity. Besides getter methods for the x- and y-coordinates, no functionality is
 * provided. This class is a helper class for the implementation of elliptic curves.
 * 
 * @author R. Haenni
 * @version 2.0
 * @param  The generic type of the two-dimensional space
 */
public class Point
	   extends UniCrypt {

	private static final long serialVersionUID = 1L;

	private final T x, y;

	protected Point(T x, T y) {
		this.x = x;
		this.y = y;
	}

	/**
	 * Creates a point for given x- and y-coordinates.
	 * 

	 * @param  The type of the resulting point coordinates
	 * @param x   The x-coordinate
	 * @param y   The y-coordinate
	 * @return The new point
	 */
	public static  Point getInstance(T x, T y) {
		if (x == null || y == null) {
			throw new IllegalArgumentException();
		}
		return new Point<>(x, y);
	}

	/**
	 * Creates the special point of infinity of the given type.
	 * 

	 * @param  The type of resulting point coordinates
	 * @return The point of infinity
	 */
	public static  Point getInstance() {
		return new Point<>(null, null);
	}

	/**
	 * Returns the point's x-coordinate (or {@code null} in case of the pint of infinity}.
	 * 

	 * @return The x-coordinate
	 */
	public T getX() {
		return this.x;
	}

	/**
	 * Returns the point's y-coordinate (or {@code null} in case of the pint of infinity}.
	 * 
	 * @return The y-coordinate
	 */
	public T getY() {
		return this.y;
	}

	@Override
	public int hashCode() {
		int hash = 5;
		hash = 59 * hash + (this.x != null ? this.x.hashCode() : 0);
		hash = 59 * hash + (this.y != null ? this.y.hashCode() : 0);
		return hash;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == null) {
			return false;
		}
		if (getClass() != obj.getClass()) {
			return false;
		}
		final Point other = (Point) obj;
		if (this.x != other.x && (this.x == null || !this.x.equals(other.x))) {
			return false;
		}
		if (this.y != other.y && (this.y == null || !this.y.equals(other.y))) {
			return false;
		}
		return true;
	}

	@Override
	protected String defaultToStringContent() {
		if (this.x == null) {
			return "INFINITY";
		}
		return this.x + "," + this.y;
	}

}