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Java > Open Source Codes > org > apache > bcel > verifier > statics > StringRepresentation


1 /*
2  * Copyright 2000-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17 package org.apache.bcel.verifier.statics;
18
19
20 import org.apache.bcel.classfile.Code;
21 import org.apache.bcel.classfile.CodeException;
22 import org.apache.bcel.classfile.ConstantClass;
23 import org.apache.bcel.classfile.ConstantDouble;
24 import org.apache.bcel.classfile.ConstantFieldref;
25 import org.apache.bcel.classfile.ConstantFloat;
26 import org.apache.bcel.classfile.ConstantInteger;
27 import org.apache.bcel.classfile.ConstantInterfaceMethodref;
28 import org.apache.bcel.classfile.ConstantLong;
29 import org.apache.bcel.classfile.ConstantMethodref;
30 import org.apache.bcel.classfile.ConstantNameAndType;
31 import org.apache.bcel.classfile.ConstantPool;
32 import org.apache.bcel.classfile.ConstantString;
33 import org.apache.bcel.classfile.ConstantUtf8;
34 import org.apache.bcel.classfile.ConstantValue;
35 import org.apache.bcel.classfile.Deprecated;
36 import org.apache.bcel.classfile.ExceptionTable;
37 import org.apache.bcel.classfile.Field;
38 import org.apache.bcel.classfile.InnerClass;
39 import org.apache.bcel.classfile.InnerClasses;
40 import org.apache.bcel.classfile.JavaClass;
41 import org.apache.bcel.classfile.LineNumber;
42 import org.apache.bcel.classfile.LineNumberTable;
43 import org.apache.bcel.classfile.LocalVariable;
44 import org.apache.bcel.classfile.LocalVariableTable;
45 import org.apache.bcel.classfile.Method;
46 import org.apache.bcel.classfile.Node;
47 import org.apache.bcel.classfile.Signature;
48 import org.apache.bcel.classfile.SourceFile;
49 import org.apache.bcel.classfile.StackMap;
50 import org.apache.bcel.classfile.Synthetic;
51 import org.apache.bcel.classfile.Unknown;
52 import org.apache.bcel.classfile.Visitor;
53 import org.apache.bcel.verifier.exc.AssertionViolatedException;
54
55 /**
56  * BCEL's Node classes (those from the classfile API that <B>accept()</B> Visitor
57  * instances) have <B>toString()</B> methods that were not designed to be robust,
58  * this gap is closed by this class.
59  * When performing class file verification, it may be useful to output which
60  * entity (e.g. a <B>Code</B> instance) is not satisfying the verifier's
61  * constraints, but in this case it could be possible for the <B>toString()</B>
62  * method to throw a RuntimeException.
63  * A (new StringRepresentation(Node n)).toString() never throws any exception.
64  * Note that this class also serves as a placeholder for more sophisticated message
65  * handling in future versions of JustIce.
66  *
67  * @version $Id: StringRepresentation.java 386056 2006-03-15 11:31:56Z tcurdt $
68  * @author Enver Haase
69  */
70 public class StringRepresentation extends org.apache.bcel.classfile.EmptyVisitor implements Visitor {
71     /** The string representation, created by a visitXXX() method, output by toString(). */
72     private String JavaDoc tostring;
73     /** The node we ask for its string representation. Not really needed; only for debug output. */
74     private Node n;
75
76     /**
77      * Creates a new StringRepresentation object which is the representation of n.
78      *
79      * @see #toString()
80      */
81     public StringRepresentation(Node n) {
82         this.n = n;
83         n.accept(this); // assign a string representation to field 'tostring' if we know n's class.
84 }
85
86     /**
87      * Returns the String representation.
88      */
89     public String JavaDoc toString() {
90 // The run-time check below is needed because we don't want to omit inheritance
91 // of "EmptyVisitor" and provide a thousand empty methods.
92 // However, in terms of performance this would be a better idea.
93 // If some new "Node" is defined in BCEL (such as some concrete "Attribute"), we
94 // want to know that this class has also to be adapted.
95 if (tostring == null) {
96             throw new AssertionViolatedException("Please adapt '" + getClass() + "' to deal with objects of class '" + n.getClass() + "'.");
97         }
98         return tostring;
99     }
100
101     /**
102      * Returns the String representation of the Node object obj;
103      * this is obj.toString() if it does not throw any RuntimeException,
104      * or else it is a string derived only from obj's class name.
105      */
106     private String JavaDoc toString(Node obj) {
107         String JavaDoc ret;
108         try {
109             ret = obj.toString();
110         }
111         catch (RuntimeException JavaDoc e) { // including ClassFormatException, trying to convert the "signature" of a ReturnaddressType LocalVariable (shouldn't occur, but people do crazy things)
112 String JavaDoc s = obj.getClass().getName();
113             s = s.substring(s.lastIndexOf(".") + 1);
114             ret = "<<" + s + ">>";
115         }
116         return ret;
117     }
118
119     ////////////////////////////////
120 // Visitor methods start here //
121 ////////////////////////////////
122 // We don't of course need to call some default implementation:
123 // e.g. we could also simply output "Code" instead of a possibly
124 // lengthy Code attribute's toString().
125 public void visitCode(Code obj) {
126         //tostring = toString(obj);
127 tostring = "<CODE>"; // We don't need real code outputs.
128 }
129
130     public void visitCodeException(CodeException obj) {
131         tostring = toString(obj);
132     }
133
134     public void visitConstantClass(ConstantClass obj) {
135         tostring = toString(obj);
136     }
137
138     public void visitConstantDouble(ConstantDouble obj) {
139         tostring = toString(obj);
140     }
141
142     public void visitConstantFieldref(ConstantFieldref obj) {
143         tostring = toString(obj);
144     }
145
146     public void visitConstantFloat(ConstantFloat obj) {
147         tostring = toString(obj);
148     }
149
150     public void visitConstantInteger(ConstantInteger obj) {
151         tostring = toString(obj);
152     }
153
154     public void visitConstantInterfaceMethodref(ConstantInterfaceMethodref obj) {
155         tostring = toString(obj);
156     }
157
158     public void visitConstantLong(ConstantLong obj) {
159         tostring = toString(obj);
160     }
161
162     public void visitConstantMethodref(ConstantMethodref obj) {
163         tostring = toString(obj);
164     }
165
166     public void visitConstantNameAndType(ConstantNameAndType obj) {
167         tostring = toString(obj);
168     }
169
170     public void visitConstantPool(ConstantPool obj) {
171         tostring = toString(obj);
172     }
173
174     public void visitConstantString(ConstantString obj) {
175         tostring = toString(obj);
176     }
177
178     public void visitConstantUtf8(ConstantUtf8 obj) {
179         tostring = toString(obj);
180     }
181
182     public void visitConstantValue(ConstantValue obj) {
183         tostring = toString(obj);
184     }
185
186     public void visitDeprecated(Deprecated JavaDoc obj) {
187         tostring = toString(obj);
188     }
189
190     public void visitExceptionTable(ExceptionTable obj) {
191         tostring = toString(obj);
192     }
193
194     public void visitField(Field obj) {
195         tostring = toString(obj);
196     }
197
198     public void visitInnerClass(InnerClass obj) {
199         tostring = toString(obj);
200     }
201
202     public void visitInnerClasses(InnerClasses obj) {
203         tostring = toString(obj);
204     }
205
206     public void visitJavaClass(JavaClass obj) {
207         tostring = toString(obj);
208     }
209
210     public void visitLineNumber(LineNumber obj) {
211         tostring = toString(obj);
212     }
213
214     public void visitLineNumberTable(LineNumberTable obj) {
215         tostring = "<LineNumberTable: " + toString(obj) + ">";
216     }
217
218     public void visitLocalVariable(LocalVariable obj) {
219         tostring = toString(obj);
220     }
221
222     public void visitLocalVariableTable(LocalVariableTable obj) {
223         tostring = "<LocalVariableTable: " + toString(obj) + ">";
224     }
225
226     public void visitMethod(Method obj) {
227         tostring = toString(obj);
228     }
229
230     public void visitSignature(Signature obj) {
231         tostring = toString(obj);
232     }
233
234     public void visitSourceFile(SourceFile obj) {
235         tostring = toString(obj);
236     }
237
238     public void visitStackMap(StackMap obj) {
239         tostring = toString(obj);
240     }
241
242     public void visitSynthetic(Synthetic obj) {
243         tostring = toString(obj);
244     }
245
246     public void visitUnknown(Unknown obj) {
247         tostring = toString(obj);
248     }
249 }
250
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