1 /*
2 * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package com.sun.beans.finder;
26
27 /**
28 * This class is designed to be a key of a cache
29 * of constructors or methods.
30 *
31 * @since 1.7
32 *
33 * @author Sergey A. Malenkov
34 */
35 final class Signature {
36 private final Class<?> type;
37 private final String name;
38 private final Class<?>[] args;
39
40 private volatile int code;
41
42 /**
43 * Constructs signature for constructor.
44 *
45 * @param type the class that contains constructor
46 * @param args the types of constructor's parameters
47 */
48 Signature(Class<?> type, Class<?>[] args) {
49 this(type, null, args);
50 }
51
52 /**
53 * Constructs signature for method.
54 *
55 * @param type the class that contains method
56 * @param name the name of the method
57 * @param args the types of method's parameters
58 */
59 Signature(Class<?> type, String name, Class<?>[] args) {
60 this.type = type;
61 this.name = name;
62 this.args = args;
63 }
64
65 /**
66 * Indicates whether some other object is "equal to" this one.
67 *
68 * @param object the reference object with which to compare
69 * @return {@code true} if this object is the same as the
70 * {@code object} argument, {@code false} otherwise
71 * @see #hashCode()
72 */
73 @Override
74 public boolean equals(Object object) {
75 if (this == object) {
76 return true;
77 }
78 if (object instanceof Signature) {
79 Signature signature = (Signature) object;
80 return isEqual(signature.type, this.type)
81 && isEqual(signature.name, this.name)
82 && isEqual(signature.args, this.args);
83 }
84 return false;
85 }
86
87 /**
88 * Indicates whether some object is "equal to" another one.
89 * This method supports {@code null} values.
90 *
91 * @param obj1 the first reference object that will compared
92 * @param obj2 the second reference object that will compared
93 * @return {@code true} if first object is the same as the second object,
94 * {@code false} otherwise
95 */
96 private static boolean isEqual(Object obj1, Object obj2) {
97 return (obj1 == null)
98 ? obj2 == null
99 : obj1.equals(obj2);
100 }
101
102 /**
103 * Indicates whether some array is "equal to" another one.
104 * This method supports {@code null} values.
105 *
106 * @param args1 the first reference array that will compared
107 * @param args2 the second reference array that will compared
108 * @return {@code true} if first array is the same as the second array,
109 * {@code false} otherwise
110 */
111 private static boolean isEqual(Class<?>[] args1, Class<?>[] args2) {
112 if ((args1 == null) || (args2 == null)) {
113 return args1 == args2;
114 }
115 if (args1.length != args2.length) {
116 return false;
117 }
118 for (int i = 0; i < args1.length; i++) {
119 if (!isEqual(args1[i], args2[i])) {
120 return false;
121 }
122 }
123 return true;
124 }
125
126 /**
127 * Returns a hash code value for the object.
128 * This method is supported for the benefit of hashtables
129 * such as {@link java.util.HashMap} or {@link java.util.HashSet}.
130 * Hash code computed using algorithm
131 * suggested in Effective Java, Item 8.
132 *
133 * @return a hash code value for this object
134 * @see #equals(Object)
135 */
136 @Override
137 public int hashCode() {
138 if (this.code == 0) {
139 int code = 17;
140 code = addHashCode(code, this.type);
141 code = addHashCode(code, this.name);
142
143 if (this.args != null) {
144 for (Class<?> arg : this.args) {
145 code = addHashCode(code, arg);
146 }
147 }
148 this.code = code;
149 }
150 return this.code;
151 }
152
153 /**
154 * Adds hash code value if specified object.
155 * This is a part of the algorithm
156 * suggested in Effective Java, Item 8.
157 *
158 * @param code current hash code value
159 * @param object object that updates hash code value
160 * @return updated hash code value
161 * @see #hashCode()
162 */
163 private static int addHashCode(int code, Object object) {
164 code *= 37;
165 return (object != null)
166 ? code + object.hashCode()
167 : code;
168 }
169 }