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Java > Open Source Codes > com > sleepycat > asm > signature > SignatureWriter


1 /***
2  * ASM: a very small and fast Java bytecode manipulation framework
3  * Copyright (c) 2000-2005 INRIA, France Telecom
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the copyright holders nor the names of its
15  * contributors may be used to endorse or promote products derived from
16  * this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28  * THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 package com.sleepycat.asm.signature;
31
32 /**
33  * A signature visitor that generates signatures in string format.
34  *
35  * @author Thomas Hallgren
36  * @author Eric Bruneton
37  */
38 public class SignatureWriter implements SignatureVisitor {
39
40     /**
41      * Buffer used to construct the signature.
42      */
43     private final StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
44
45     /**
46      * Indicates if the signature contains formal type parameters.
47      */
48     private boolean hasFormals;
49
50     /**
51      * Indicates if the signature contains method parameter types.
52      */
53     private boolean hasParameters;
54
55     /**
56      * Stack used to keep track of class types that have arguments. Each element
57      * of this stack is a boolean encoded in one bit. The top of the stack is
58      * the lowest order bit. Pushing false = *2, pushing true = *2+1, popping =
59      * /2.
60      */
61     private int argumentStack;
62
63     /**
64      * Constructs a new {@link SignatureWriter} object.
65      */
66     public SignatureWriter() {
67     }
68
69     // ------------------------------------------------------------------------
70 // Implementation of the SignatureVisitor interface
71 // ------------------------------------------------------------------------
72
73     public void visitFormalTypeParameter(String JavaDoc name) {
74         if (!hasFormals) {
75             hasFormals = true;
76             buf.append('<');
77         }
78         buf.append(name);
79         buf.append(':');
80     }
81
82     public SignatureVisitor visitClassBound() {
83         return this;
84     }
85
86     public SignatureVisitor visitInterfaceBound() {
87         buf.append(':');
88         return this;
89     }
90
91     public SignatureVisitor visitSuperclass() {
92         endFormals();
93         return this;
94     }
95
96     public SignatureVisitor visitInterface() {
97         return this;
98     }
99
100     public SignatureVisitor visitParameterType() {
101         endFormals();
102         if (!hasParameters) {
103             hasParameters = true;
104             buf.append('(');
105         }
106         return this;
107     }
108
109     public SignatureVisitor visitReturnType() {
110         endFormals();
111         if (!hasParameters) {
112             buf.append('(');
113         }
114         buf.append(')');
115         return this;
116     }
117
118     public SignatureVisitor visitExceptionType() {
119         buf.append('^');
120         return this;
121     }
122
123     public void visitBaseType(char descriptor) {
124         buf.append(descriptor);
125     }
126
127     public void visitTypeVariable(String JavaDoc name) {
128         buf.append('T');
129         buf.append(name);
130         buf.append(';');
131     }
132
133     public SignatureVisitor visitArrayType() {
134         buf.append('[');
135         return this;
136     }
137
138     public void visitClassType(String JavaDoc name) {
139         buf.append('L');
140         buf.append(name);
141         argumentStack *= 2;
142     }
143
144     public void visitInnerClassType(String JavaDoc name) {
145         endArguments();
146         buf.append('.');
147         buf.append(name);
148         argumentStack *= 2;
149     }
150
151     public void visitTypeArgument() {
152         if (argumentStack % 2 == 0) {
153             ++argumentStack;
154             buf.append('<');
155         }
156         buf.append('*');
157     }
158
159     public SignatureVisitor visitTypeArgument(char wildcard) {
160         if (argumentStack % 2 == 0) {
161             ++argumentStack;
162             buf.append('<');
163         }
164         if (wildcard != '=') {
165             buf.append(wildcard);
166         }
167         return this;
168     }
169
170     public void visitEnd() {
171         endArguments();
172         buf.append(';');
173     }
174
175     /**
176      * Returns the signature that was built by this signature writer.
177      *
178      * @return the signature that was built by this signature writer.
179      */
180     public String JavaDoc toString() {
181         return buf.toString();
182     }
183
184     // ------------------------------------------------------------------------
185 // Utility methods
186 // ------------------------------------------------------------------------
187
188     /**
189      * Ends the formal type parameters section of the signature.
190      */
191     private void endFormals() {
192         if (hasFormals) {
193             hasFormals = false;
194             buf.append('>');
195         }
196     }
197
198     /**
199      * Ends the type arguments of a class or inner class type.
200      */
201     private void endArguments() {
202         if (argumentStack % 2 == 1) {
203             buf.append('>');
204         }
205         argumentStack /= 2;
206     }
207 }
208
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