001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.functor.adapter;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.functor.Function;
022 import org.apache.commons.functor.Procedure;
023
024 /**
025 * Adapts a {@link Function Function}
026 * to the {@link Procedure Procedure}
027 * interface by ignoring the value returned
028 * by the function.
029 * <p/>
030 * Note that although this class implements
031 * {@link Serializable}, a given instance will
032 * only be truly <code>Serializable</code> if the
033 * underlying function is. Attempts to serialize
034 * an instance whose delegate is not
035 * <code>Serializable</code> will result in an exception.
036 *
037 * @version $Revision: 1156778 $ $Date: 2011-08-11 21:50:51 +0200 (Thu, 11 Aug 2011) $
038 * @author Rodney Waldhoff
039 */
040 public final class FunctionProcedure implements Procedure, Serializable {
041 /**
042 * serialVersionUID declaration.
043 */
044 private static final long serialVersionUID = -7300031015086684901L;
045 /** The {@link Function Function} I'm wrapping. */
046 private final Function<?> function;
047
048 /**
049 * Create an {@link Procedure Procedure} wrapping
050 * the given {@link Function Function}.
051 * @param function the {@link Function Function} to wrap
052 */
053 public FunctionProcedure(Function<?> function) {
054 if (function == null) {
055 throw new IllegalArgumentException("Function argument was null");
056 }
057 this.function = function;
058 }
059
060 /**
061 * {@inheritDoc}
062 * {@link Function#evaluate Evaluate} my function,
063 * but ignore its returned value.
064 */
065 public void run() {
066 function.evaluate();
067 }
068
069 /**
070 * {@inheritDoc}
071 */
072 public boolean equals(Object that) {
073 return that == this || (that instanceof FunctionProcedure && equals((FunctionProcedure) that));
074 }
075
076 /**
077 * Learn whether another FunctionProcedure is equal to this.
078 * @param that FunctionProcedure to test
079 * @return boolean
080 */
081 public boolean equals(FunctionProcedure that) {
082 return null != that && (null == function ? null == that.function : function.equals(that.function));
083 }
084
085 /**
086 * {@inheritDoc}
087 */
088 public int hashCode() {
089 int hash = "FunctionProcedure".hashCode();
090 if (null != function) {
091 hash ^= function.hashCode();
092 }
093 return hash;
094 }
095
096 /**
097 * {@inheritDoc}
098 */
099 public String toString() {
100 return "FunctionProcedure<" + function + ">";
101 }
102
103 /**
104 * Adapt the given, possibly-<code>null</code>,
105 * {@link Function Function} to the
106 * {@link Procedure Procedure} interface.
107 * When the given <code>Function</code> is <code>null</code>,
108 * returns <code>null</code>.
109 *
110 * @param function the possibly-<code>null</code>
111 * {@link Function Function} to adapt
112 * @return a {@link Procedure Procedure} wrapping the given
113 * {@link Function Function}, or <code>null</code>
114 * if the given <code>Function</code> is <code>null</code>
115 */
116 public static FunctionProcedure adapt(Function<?> function) {
117 return null == function ? null : new FunctionProcedure(function);
118 }
119
120 }