| /* |
| * Copyright 2003,2004 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.commons.functor.core; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.functor.UnaryFunction; |
| import org.apache.commons.functor.UnaryPredicate; |
| |
| /** |
| * {@link #evaluate Evaluates} to its input argument. |
| * |
| * {@link #test Tests} to the <code>boolean</code> |
| * value of the <code>Boolean</code>-valued parameter. |
| * The {@link #test} method throws an exception if |
| * the parameter isn't a non-<code>null</code> |
| * <code>Boolean</code>. |
| * |
| * @version $Revision$ $Date$ |
| * @author Rodney Waldhoff |
| */ |
| public final class Identity implements UnaryFunction, UnaryPredicate, Serializable { |
| |
| // constructor |
| // ------------------------------------------------------------------------ |
| public Identity() { |
| } |
| |
| // function interface |
| // ------------------------------------------------------------------------ |
| public Object evaluate(Object obj) { |
| return obj; |
| } |
| |
| public boolean test(Object obj) { |
| return test((Boolean)obj); |
| } |
| |
| public boolean test(Boolean bool) { |
| return bool.booleanValue(); |
| } |
| |
| public boolean equals(Object that) { |
| return (that instanceof Identity); |
| } |
| |
| public int hashCode() { |
| return "Identity".hashCode(); |
| } |
| |
| public String toString() { |
| return "Identity"; |
| } |
| |
| // static methods |
| // ------------------------------------------------------------------------ |
| public static Identity instance() { |
| return INSTANCE; |
| } |
| |
| // static attributes |
| // ------------------------------------------------------------------------ |
| private static final Identity INSTANCE = new Identity(); |
| } |