package agents.anac.y2010.Southampton.utils;

public class Pair<A, B> {

	public final A fst;
	public final B snd;

	public Pair(A fst, B snd) {
		this.fst = fst;
		this.snd = snd;
	}

	public String toString() {
		return "Pair[" + fst + "," + snd + "]";
	}

	private static boolean equals(Object x, Object y) {
		return (x == null && y == null) || (x != null && x.equals(y));
	}

	public boolean equals(Object other) {
		return other instanceof Pair && equals(fst, ((Pair<?, ?>) other).fst) && equals(snd, ((Pair<?, ?>) other).snd);
	}

	public int hashCode() {
		if (fst == null)
			return (snd == null) ? 0 : snd.hashCode() + 1;
		else if (snd == null)
			return fst.hashCode() + 2;
		else
			return fst.hashCode() * 17 + snd.hashCode();
	}

	public static <A, B> Pair<A, B> of(A a, B b) {
		return new Pair<A, B>(a, b);
	}
}