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.Procedure;
022 import org.apache.commons.functor.UnaryProcedure;
023
024 /**
025 * Adapts a
026 * {@link UnaryProcedure UnaryProcedure}
027 * to the
028 * {@link Procedure Procedure} interface
029 * using a constant unary argument.
030 * <p/>
031 * Note that although this class implements
032 * {@link Serializable}, a given instance will
033 * only be truly <code>Serializable</code> if the
034 * underlying objects are. Attempts to serialize
035 * an instance whose delegates are not
036 * <code>Serializable</code> will result in an exception.
037 *
038 * @version $Revision: 1156320 $ $Date: 2011-08-10 21:14:50 +0200 (Wed, 10 Aug 2011) $
039 * @author Rodney Waldhoff
040 */
041 public final class BoundProcedure implements Procedure, Serializable {
042 /**
043 * serialVersionUID declaration.
044 */
045 private static final long serialVersionUID = -6010802933400471747L;
046 /** The {@link UnaryProcedure UnaryProcedure} I'm wrapping. */
047 private final UnaryProcedure<Object> procedure;
048 /** The parameter to pass to {@code procedure}. */
049 private final Object param;
050
051 /**
052 * Create a new BoundProcedure instance.
053 * @param <A> arg type
054 * @param procedure the procedure to adapt
055 * @param arg the constant argument to use
056 */
057 @SuppressWarnings("unchecked")
058 public <A> BoundProcedure(UnaryProcedure<? super A> procedure, A arg) {
059 if (procedure == null) {
060 throw new IllegalArgumentException("UnaryProcedure argument was null");
061 }
062 this.procedure = (UnaryProcedure<Object>) procedure;
063 this.param = arg;
064 }
065
066 /**
067 * {@inheritDoc}
068 */
069 public void run() {
070 procedure.run(param);
071 }
072
073 /**
074 * {@inheritDoc}
075 */
076 public boolean equals(Object that) {
077 return that == this || (that instanceof BoundProcedure && equals((BoundProcedure) that));
078 }
079
080 /**
081 * Learn whether a given BoundProcedure is equal to this.
082 * @param that the BoundProcedure to test
083 * @return boolean
084 */
085 public boolean equals(BoundProcedure that) {
086 return null != that
087 && (null == procedure ? null == that.procedure : procedure.equals(that.procedure))
088 && (null == param ? null == that.param : param.equals(that.param));
089 }
090
091 /**
092 * {@inheritDoc}
093 */
094 public int hashCode() {
095 int hash = "BoundProcedure".hashCode();
096 if (null != procedure) {
097 hash <<= 2;
098 hash ^= procedure.hashCode();
099 }
100 if (null != param) {
101 hash <<= 2;
102 hash ^= param.hashCode();
103 }
104 return hash;
105 }
106
107 /**
108 * {@inheritDoc}
109 */
110 public String toString() {
111 return "BoundProcedure<" + procedure + "(" + param + ")>";
112 }
113
114 /**
115 * Adapt the given, possibly-<code>null</code>,
116 * {@link UnaryProcedure UnaryProcedure} to the
117 * {@link Procedure Procedure} interface by binding
118 * the specified <code>Object</code> as a constant
119 * argument.
120 * When the given <code>UnaryProcedure</code> is <code>null</code>,
121 * returns <code>null</code>.
122 *
123 * @param <A> arg type
124 * @param procedure the possibly-<code>null</code>
125 * {@link UnaryProcedure UnaryProcedure} to adapt
126 * @param arg the object to bind as a constant argument
127 * @return a <code>BoundProcedure</code> wrapping the given
128 * {@link UnaryProcedure UnaryProcedure}, or <code>null</code>
129 * if the given <code>UnaryProcedure</code> is <code>null</code>
130 */
131 public static <A> BoundProcedure bind(UnaryProcedure<? super A> procedure, A arg) {
132 return null == procedure ? null : new BoundProcedure(procedure, arg);
133 }
134
135 }