| /******************************************************************************* |
| * Copyright (c) 2013 Oracle. All rights reserved. |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v1.0, which accompanies this distribution |
| * and is available at http://www.eclipse.org/legal/epl-v10.html. |
| * |
| * Contributors: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.utility; |
| |
| import org.eclipse.jpt.common.utility.internal.ObjectTools; |
| import org.eclipse.jpt.common.utility.transformer.Transformer; |
| |
| /** |
| * Straightforward definition of an object pairing. |
| * The left and right values are immutable. |
| * <p> |
| * Provisional API: This interface is part of an interim API that is still |
| * under development and expected to change significantly before reaching |
| * stability. It is available at this early stage to solicit feedback from |
| * pioneering adopters on the understanding that any code that uses this API |
| * will almost certainly be broken (repeatedly) as the API evolves. |
| * |
| * @param <L> the type of the pair's left value |
| * @param <R> the type of the pair's right value |
| * @see org.eclipse.jpt.common.utility.Association |
| */ |
| public interface Pair<L, R> { |
| |
| /** |
| * Return the pair's left value. |
| */ |
| L getLeft(); |
| |
| @SuppressWarnings("rawtypes") |
| Transformer LEFT_TRANSFORMER = new LeftTransformer(); |
| class LeftTransformer<L, R> |
| implements Transformer<Pair<L, R>, L> |
| { |
| public L transform(Pair<L, R> pair) { |
| return pair.getLeft(); |
| } |
| @Override |
| public String toString() { |
| return ObjectTools.singletonToString(this); |
| } |
| } |
| |
| /** |
| * Return the pair's right value. |
| */ |
| R getRight(); |
| |
| @SuppressWarnings("rawtypes") |
| Transformer RIGHT_TRANSFORMER = new RightTransformer(); |
| class RightTransformer<L, R> |
| implements Transformer<Pair<L, R>, R> |
| { |
| public R transform(Pair<L, R> pair) { |
| return pair.getRight(); |
| } |
| @Override |
| public String toString() { |
| return ObjectTools.singletonToString(this); |
| } |
| } |
| |
| /** |
| * Return whether the pairs' left and right values |
| * are equal. |
| */ |
| boolean equals(Object o); |
| |
| /** |
| * Return a hash code that is a XOR of the hash codes of the pair's |
| * left and right values. |
| */ |
| int hashCode(); |
| } |