| /* |
| * 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.adapter; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.functor.Function; |
| import org.apache.commons.functor.Predicate; |
| import org.apache.commons.lang3.Validate; |
| |
| /** |
| * Adapts a |
| * {@link Predicate Predicate} |
| * to the |
| * {@link Function Function} interface. |
| * <p/> |
| * Note that although this class implements |
| * {@link Serializable}, a given instance will |
| * only be truly <code>Serializable</code> if the |
| * underlying predicate is. Attempts to serialize |
| * an instance whose delegate is not |
| * <code>Serializable</code> will result in an exception. |
| * |
| * @param <A> the argument type. |
| * @version $Revision$ $Date$ |
| */ |
| public final class PredicateFunction<A> implements Function<A, Boolean>, Serializable { |
| /** |
| * serialVersionUID declaration. |
| */ |
| private static final long serialVersionUID = 5660724725036398625L; |
| /** The {@link Predicate Predicate} I'm wrapping. */ |
| private final Predicate<? super A> predicate; |
| |
| /** |
| * Create a new PredicateFunction. |
| * @param predicate to adapt |
| */ |
| public PredicateFunction(Predicate<? super A> predicate) { |
| this.predicate = Validate.notNull(predicate, "Predicate argument was null"); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * Returns <code>Boolean.TRUE</code> (<code>Boolean.FALSE</code>) |
| * when the {@link Predicate#test test} method of my underlying |
| * predicate returns <code>true</code> (<code>false</code>). |
| * |
| * @return a non-<code>null</code> <code>Boolean</code> instance |
| */ |
| public Boolean evaluate(A obj) { |
| return Boolean.valueOf(predicate.test(obj)); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (!(obj instanceof PredicateFunction<?>)) { |
| return false; |
| } |
| PredicateFunction<?> that = (PredicateFunction<?>) obj; |
| return this.predicate.equals(that.predicate); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| int hash = "PredicateFunction".hashCode(); |
| hash ^= predicate.hashCode(); |
| return hash; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "PredicateFunction<" + predicate + ">"; |
| } |
| |
| /** |
| * Adapt a Predicate to the Function interface. |
| * @param <A> the argument type. |
| * @param predicate to adapt |
| * @return PredicateFunction |
| */ |
| public static <A> PredicateFunction<A> adapt(Predicate<? super A> predicate) { |
| return null == predicate ? null : new PredicateFunction<A>(predicate); |
| } |
| |
| } |