package geniusweb.blingbling.Ranknet;

import java.util.Objects;

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