package ssj.algorithm.lang;

/**

* Created by shenshijun on 15/2/14.

*/

final public class Tuple2<F, S> {

final private F first;

final private S second;

private Integer hash_code = null;

private String to_string = null;

public F getFirst() {

return first;

}

public S getSecond() {

return second;

}

@Override

public String toString() {

if (to_string == null) {

final StringBuilder sb = new StringBuilder("Tuple2{");

sb.append("first=").append(first);

sb.append(", second=").append(second);

sb.append('}');

to_string = sb.toString();

}

return to_string;

}

public static <F, S> Tuple2<F, S> empty() {

return new Tuple2<>(null, null);

}

public boolean isEmpty() {

return getFirst() == null && getSecond() == null;

}

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

Tuple2 tuple2 = (Tuple2) o;

if (first != null ? !first.equals(tuple2.first) : tuple2.first != null) return false;

if (second != null ? !second.equals(tuple2.second) : tuple2.second != null) return false;

return true;

}

@Override

public int hashCode() {

if (hash_code == null) {

int result = first != null ? first.hashCode() : 0;

result = 31 * result + (second != null ? second.hashCode() : 0);

hash_code = result;

}

return hash_code;

}

public Tuple2(F first, S second) {

this.first = first;

this.second = second;

}

}