1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.functor.core.collection;
18
19 import java.io.Serializable;
20 import java.lang.reflect.Array;
21 import java.util.Collection;
22
23 import org.apache.commons.functor.UnaryFunction;
24
25 /**
26 * Returns the size of the specified Collection, or the length
27 * of the specified array or String.
28 * @version $Revision: 1166334 $ $Date: 2011-09-07 21:37:49 +0200 (Wed, 07 Sep 2011) $
29 * @author Rodney Waldhoff
30 */
31 public final class Size<A> implements UnaryFunction<A, Integer>, Serializable {
32
33 /**
34 * serialVersionUID declaration.
35 */
36 private static final long serialVersionUID = -12374650738412129L;
37 private static final Size<Object> INSTANCE = new Size<Object>();
38
39 // constructor
40 // ------------------------------------------------------------------------
41 /**
42 * Create a new Size.
43 */
44 public Size() { }
45
46 /**
47 * {@inheritDoc}
48 */
49 public Integer evaluate(Object obj) {
50 if (obj instanceof Collection<?>) {
51 return evaluate((Collection<?>) obj);
52 }
53 if (obj instanceof String) {
54 return evaluate((String) obj);
55 }
56 if (null != obj && obj.getClass().isArray()) {
57 return evaluateArray(obj);
58 }
59 if (null == obj) {
60 throw new IllegalArgumentException("Argument must not be null");
61 }
62 throw new IllegalArgumentException("Expected Collection, String or Array, found " + obj);
63 }
64
65 /**
66 * {@inheritDoc}
67 */
68 public boolean equals(Object that) {
69 return that instanceof Size<?>;
70 }
71
72 /**
73 * {@inheritDoc}
74 */
75 public int hashCode() {
76 return "Size".hashCode();
77 }
78
79 /**
80 * {@inheritDoc}
81 */
82 public String toString() {
83 return "Size()";
84 }
85
86 /**
87 * Get a Size instance.
88 * @return Size
89 */
90 public static Size<Object> instance() {
91 return INSTANCE;
92 }
93
94 /**
95 * Evaluate a Collection.
96 * @param col to evaluate
97 * @return Integer
98 */
99 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 }