/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.waveprotocol.wave.model.util;
/**
* An immutable ordered pair of typed objects.
*
* Essentially the same as com.google.common.base.Pair.
* (we avoid external dependencies from model/)
*
*
*
* @param <A> Type of value 1
* @param <B> Type of value 2
*/
public class Pair<A, B> {
/**
* Static constructor to save typing on generic arguments.
*/
public static <A, B> Pair<A, B> of(A a, B b) {
return new Pair<A, B>(a, b);
}
/**
* The first element of the pair; see also {@link #getFirst}.
*/
public final A first;
/**
* The second element of the pair; see also {@link #getSecond}.
*/
public final B second;
/**
* Pair constructor
*
* @param first Value 1
* @param second Value 2
*/
public Pair(A first, B second) {
this.first = first;
this.second = second;
}
/**
* Copy constructor
*
* @param pair Pair to shallow copy from
*/
public Pair(Pair<? extends A, ? extends B> pair) {
first = pair.first;
second = pair.second;
}
/**
* Returns the first element of this pair; see also {@link #first}.
*/
public A getFirst() {
return first;
}
/**
* Returns the second element of this pair; see also {@link #second}.
*/
public B getSecond() {
return second;
}
/**
* {@inheritDoc}
*
* NOTE: Not safe to override this method, hence final.
*/
@Override
public final boolean equals(Object o) {
if (o == null) return false;
if (o == this) return true;
if (o instanceof Pair) {
Pair<?,?> p = (Pair<?,?>) o;
return
(p.first == first || (first != null && first.equals(p.first))) &&
(p.second == second || (second != null && second.equals(p.second)));
}
return false;
}
/**
* {@inheritDoc}
*
* NOTE: Not safe to override this method, hence final.
*/
@Override
public final int hashCode() {
return (first == null ? 0 : first.hashCode()) + 37 * (second == null ? 0 : second.hashCode());
}
/** {@inheritDoc} */
@Override
public String toString() {
return "(" + String.valueOf(first) + "," + String.valueOf(second) + ")";
}
}