| /* |
| * 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.NullaryFunction; |
| import org.apache.commons.functor.NullaryPredicate; |
| import org.apache.commons.lang3.Validate; |
| |
| /** |
| * A {@link NullaryFunction NullaryFunction} |
| * similiar to Java's "ternary" |
| * or "conditional" operator (<code>? :</code>). |
| * Given a {@link NullaryPredicate predicate} |
| * <i>p</i> and {@link NullaryFunction functions} |
| * <i>f</i> and <i>g</i>, {@link #evaluate evaluates} |
| * to |
| * <code>p.test() ? f.evaluate() : g.evaluate()</code>. |
| * <p> |
| * Note that although this class implements |
| * {@link Serializable}, a given instance will |
| * only be truly <code>Serializable</code> if all the |
| * underlying functors are. Attempts to serialize |
| * an instance whose delegates are not all |
| * <code>Serializable</code> will result in an exception. |
| * </p> |
| * @param <T> the returned value type. |
| * @version $Revision: 1365329 $ $Date: 2012-07-24 19:34:23 -0300 (Tue, 24 Jul 2012) $ |
| */ |
| public final class ConditionalNullaryFunction<T> implements NullaryFunction<T>, Serializable { |
| /** |
| * serialVersionUID declaration. |
| */ |
| private static final long serialVersionUID = 4214871352184887792L; |
| |
| /** Base hash integer used to shift hash. */ |
| private static final int HASH_SHIFT = 4; |
| // attributes |
| // ------------------------------------------------------------------------ |
| /** |
| * the condition to be evaluated. |
| */ |
| private final NullaryPredicate ifPred; |
| /** |
| * the function executed if the condition is satisfied. |
| */ |
| private final NullaryFunction<? extends T> thenFunc; |
| /** |
| * the function executed if the condition is not satisfied. |
| */ |
| private final NullaryFunction<? extends T> elseFunc; |
| |
| // constructor |
| // ------------------------------------------------------------------------ |
| /** |
| * Create a new ConditionalNullaryFunction. |
| * @param ifPred if |
| * @param thenFunc then |
| * @param elseFunc else |
| */ |
| public ConditionalNullaryFunction(NullaryPredicate ifPred, NullaryFunction<? extends T> thenFunc, |
| NullaryFunction<? extends T> elseFunc) { |
| this.ifPred = Validate.notNull(ifPred, "NullaryPredicate argument was null"); |
| this.thenFunc = Validate.notNull(thenFunc, "'then' NullaryFunction argument was null"); |
| this.elseFunc = Validate.notNull(elseFunc, "'else' NullaryFunction argument was null"); |
| } |
| |
| // predicate interface |
| // ------------------------------------------------------------------------ |
| /** |
| * {@inheritDoc} |
| */ |
| public T evaluate() { |
| if (ifPred.test()) { |
| return thenFunc.evaluate(); |
| } else { |
| return elseFunc.evaluate(); |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (!(obj instanceof ConditionalNullaryFunction<?>)) { |
| return false; |
| } |
| ConditionalNullaryFunction<?> that = (ConditionalNullaryFunction<?>) obj; |
| return this.ifPred.equals(that.ifPred) |
| && this.thenFunc.equals(that.thenFunc) |
| && this.elseFunc.equals(that.elseFunc); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| int hash = "ConditionalNullaryFunction".hashCode(); |
| hash <<= HASH_SHIFT; |
| hash ^= ifPred.hashCode(); |
| hash <<= HASH_SHIFT; |
| hash ^= thenFunc.hashCode(); |
| hash <<= HASH_SHIFT; |
| hash ^= elseFunc.hashCode(); |
| return hash; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "ConditionalNullaryFunction<" + ifPred + "?" + thenFunc + ":" + elseFunc + ">"; |
| } |
| |
| } |