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.core.collection;
018
019 import java.io.Serializable;
020 import java.lang.reflect.Array;
021 import java.util.Collection;
022
023 import org.apache.commons.functor.UnaryFunction;
024
025 /**
026 * Returns the size of the specified Collection, or the length
027 * of the specified array or String.
028 * @version $Revision: 1166334 $ $Date: 2011-09-07 21:37:49 +0200 (Wed, 07 Sep 2011) $
029 * @author Rodney Waldhoff
030 */
031 public final class Size<A> implements UnaryFunction<A, Integer>, Serializable {
032
033 /**
034 * serialVersionUID declaration.
035 */
036 private static final long serialVersionUID = -12374650738412129L;
037 private static final Size<Object> INSTANCE = new Size<Object>();
038
039 // constructor
040 // ------------------------------------------------------------------------
041 /**
042 * Create a new Size.
043 */
044 public Size() { }
045
046 /**
047 * {@inheritDoc}
048 */
049 public Integer evaluate(Object obj) {
050 if (obj instanceof Collection<?>) {
051 return evaluate((Collection<?>) obj);
052 }
053 if (obj instanceof String) {
054 return evaluate((String) obj);
055 }
056 if (null != obj && obj.getClass().isArray()) {
057 return evaluateArray(obj);
058 }
059 if (null == obj) {
060 throw new IllegalArgumentException("Argument must not be null");
061 }
062 throw new IllegalArgumentException("Expected Collection, String or Array, found " + obj);
063 }
064
065 /**
066 * {@inheritDoc}
067 */
068 public boolean equals(Object that) {
069 return that instanceof Size<?>;
070 }
071
072 /**
073 * {@inheritDoc}
074 */
075 public int hashCode() {
076 return "Size".hashCode();
077 }
078
079 /**
080 * {@inheritDoc}
081 */
082 public String toString() {
083 return "Size()";
084 }
085
086 /**
087 * Get a Size instance.
088 * @return Size
089 */
090 public static Size<Object> instance() {
091 return INSTANCE;
092 }
093
094 /**
095 * Evaluate a Collection.
096 * @param col to evaluate
097 * @return Integer
098 */
099 private int evaluate(Collection<?> col) {
100 return col.size();
101 }
102
103 /**
104 * Evaluate a String.
105 * @param str to evaluate
106 * @return Integer
107 */
108 private int evaluate(String str) {
109 return str.length();
110 }
111
112 /**
113 * Evaluate an array.
114 * @param array to evaluate
115 * @return Integer
116 */
117 private int evaluateArray(Object array) {
118 return Array.getLength(array);
119 }
120
121 }