| // Copyright 2010 The Apache Software Foundation |
| // |
| // Licensed 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.apache.tapestry5.func; |
| |
| import java.util.Objects; |
| |
| /** |
| * A Tuple holds two values of two different types. |
| * |
| * @param <A> first type |
| * @param <B> second type |
| * @since 5.3 |
| */ |
| public class Tuple<A, B> |
| { |
| public final A first; |
| |
| public final B second; |
| |
| public Tuple(A first, B second) |
| { |
| this.first = first; |
| this.second = second; |
| } |
| |
| public static <X, Y> Tuple<X, Y> create(X first, Y second) |
| { |
| return new Tuple<X, Y>(first, second); |
| } |
| |
| /** |
| * Returns the values of the tuple, separated by commas, enclosed in parenthesis. Example: |
| * <code>("Ace", "Spades")</code>. |
| */ |
| @Override |
| public String toString() |
| { |
| StringBuilder builder = new StringBuilder("("); |
| |
| builder.append(String.valueOf(first)); |
| builder.append(", "); |
| builder.append(String.valueOf(second)); |
| |
| extendDescription(builder); |
| |
| return builder.append(')').toString(); |
| } |
| |
| /** |
| * Overriden in subclasses to write additional values into the |
| * description. |
| * |
| * @param builder |
| */ |
| protected void extendDescription(StringBuilder builder) |
| { |
| } |
| |
| /** Utility for comparing two values, either of which may be null. */ |
| static boolean isEqual(Object left, Object right) |
| { |
| return left == right || (left != null && left.equals(right)); |
| } |
| |
| /** |
| * Compares this Tuple to another object. Equality is defined by: other object is not null, |
| * is same class as this Tuple, and all values are themselves equal. |
| */ |
| @Override |
| public boolean equals(Object obj) |
| { |
| if (obj == this) |
| return true; |
| |
| if (obj == null || !(obj.getClass() == getClass())) |
| return false; |
| |
| return isMatch(obj); |
| } |
| |
| /** |
| * Returns a hash code value for the tuple, based on its values. |
| * |
| * @return a hash code value for this tuple. |
| * @since 5.7 |
| */ |
| @Override |
| public int hashCode() |
| { |
| return Objects.hash(this.first, this.second); |
| } |
| |
| /** |
| * The heart of {@link #equals(Object)}; the other object is the same class as this object. |
| * |
| * @param other |
| * other tuple to compare |
| * @return true if all values stored in tuple match |
| */ |
| protected boolean isMatch(Object other) |
| { |
| Tuple<?, ?> tuple = (Tuple<?, ?>) other; |
| |
| return isEqual(first, tuple.first) && isEqual(second, tuple.second); |
| } |
| } |