| /* |
| * 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.apache.commons.functor.core.composite; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.functor.BinaryPredicate; |
| import org.apache.commons.lang3.Validate; |
| |
| /** |
| * Transposes (swaps) the arguments to some other |
| * {@link BinaryPredicate predicate}. |
| * For example, given a predicate <i>p</i> |
| * and the ordered pair of arguments <i>a</i>, |
| * <i>b</i>. |
| * {@link #test tests} |
| * <code>p.test(b,a)</code>. |
| * <p> |
| * Note that although this class implements |
| * {@link Serializable}, a given instance will |
| * only be truly <code>Serializable</code> if the |
| * underlying functor is. Attempts to serialize |
| * an instance whose delegate is not |
| * <code>Serializable</code> will result in an exception. |
| * </p> |
| * @param <L> the left argument type. |
| * @param <R> the right argument type. |
| * @version $Revision$ $Date$ |
| */ |
| public class TransposedPredicate<L, R> implements BinaryPredicate<L, R>, Serializable { |
| /** |
| * serialVersionUID declaration. |
| */ |
| private static final long serialVersionUID = 3441209087576289240L; |
| // attributes |
| // ------------------------------------------------------------------------ |
| /** |
| * The adapted predicate. |
| */ |
| private final BinaryPredicate<? super R, ? super L> predicate; |
| |
| // constructor |
| // ------------------------------------------------------------------------ |
| /** |
| * Create a new TransposedPredicate. |
| * @param predicate the BinaryPredicate to transpose |
| */ |
| public TransposedPredicate(BinaryPredicate<? super R, ? super L> predicate) { |
| this.predicate = Validate.notNull(predicate, "BinaryPredicate argument must not be null"); |
| } |
| |
| // functor interface |
| // ------------------------------------------------------------------------ |
| /** |
| * {@inheritDoc} |
| */ |
| public final boolean test(L left, R right) { |
| return predicate.test(right, left); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object that) { |
| return that == this || (that instanceof TransposedPredicate<?, ?> && equals((TransposedPredicate<?, ?>) that)); |
| } |
| |
| /** |
| * Learn whether another TransposedPredicate is equal to this. |
| * @param that the TransposedPredicate to test |
| * @return boolean |
| */ |
| public boolean equals(TransposedPredicate<?, ?> that) { |
| return null != that && (null == predicate ? null == that.predicate : predicate.equals(that.predicate)); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| int hash = "TransposedPredicate".hashCode(); |
| if (null != predicate) { |
| hash ^= predicate.hashCode(); |
| } |
| return hash; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "TransposedPredicate<" + predicate + ">"; |
| } |
| |
| // static |
| // ------------------------------------------------------------------------ |
| /** |
| * Return the transposition of <code>p</code>. |
| * |
| * @param <L> the left argument type. |
| * @param <R> the right argument type. |
| * @param p BinaryPredicate to transpose |
| * @return TransposedPredicate |
| */ |
| public static <L, R> TransposedPredicate<R, L> transpose(BinaryPredicate<? super L, ? super R> p) { |
| return null == p ? null : new TransposedPredicate<R, L>(p); |
| } |
| |
| } |