TraceClassVisitor


1   /***
2    * ASM: a very small and fast Java bytecode manipulation framework
3    * Copyright (c) 2000,2002,2003 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   * Contact: Eric.Bruneton@rd.francetelecom.com
31   *
32   * Author: Eric Bruneton
33   */
34  
35  package org.logicalcobwebs.asm.util;
36  
37  import org.logicalcobwebs.asm.ClassVisitor;
38  import org.logicalcobwebs.asm.CodeVisitor;
39  import org.logicalcobwebs.asm.Constants;
40  import org.logicalcobwebs.asm.ClassReader;
41  import org.logicalcobwebs.asm.Attribute;
42  
43  import java.io.PrintWriter  ;
44  
45  /**
46   * A {@link PrintClassVisitor PrintClassVisitor} that prints a disassembled
47   * view of the classes it visits. This class visitor can be used alone (see the
48   * {@link #main main} method) to disassemble a class. It can also be used in
49   * the middle of class visitor chain to trace the class that is visited at a
50   * given point in this chain. This may be uselful for debugging purposes.
51   * <p>
52   * The trace printed when visiting the <tt>Hello</tt> class is the following:
53   * <p>
54   * <blockquote>
55   * <pre>
56   * // compiled from Hello.java
57   * public class Hello {
58   *
59   *   public static main ([Ljava/lang/String;)V
60   *     GETSTATIC java/lang/System out Ljava/io/PrintStream;
61   *     LDC "hello"
62   *     INVOKEVIRTUAL java/io/PrintStream println (Ljava/lang/String;)V
63   *     RETURN
64   *     MAXSTACK = 2
65   *     MAXLOCALS = 1
66   *
67   *   public &lt;init&gt; ()V
68   *     ALOAD 0
69   *     INVOKESPECIAL java/lang/Object &lt;init&gt; ()V
70   *     RETURN
71   *     MAXSTACK = 1
72   *     MAXLOCALS = 1
73   *
74   * }
75   * </pre>
76   * </blockquote>
77   * where <tt>Hello</tt> is defined by:
78   * <p>
79   * <blockquote>
80   * <pre>
81   * public class Hello {
82   *
83   *   public static void main (String[] args) {
84   *     System.out.println("hello");
85   *   }
86   * }
87   * </pre>
88   * </blockquote>
89   */
90  
91  public class TraceClassVisitor extends PrintClassVisitor {
92  
93    /**
94     * The {@link ClassVisitor ClassVisitor} to which this visitor delegates
95     * calls. May be <tt>null</tt>.
96     */
97  
98    protected final ClassVisitor cv;
99  
100   /**
101    * Prints a disassembled view of the given class to the standard output.
102    * <p>
103    * Usage: TraceClassVisitor &lt;fully qualified class name&gt;
104    *
105    * @param args the command line arguments.
106    *
107    * @throws Exception if the class cannot be found, or if an IO exception
108    *      occurs.
109    */
110 
111   public static void main (final String  [] args) throws Exception   {
112     if (args.length == 0) {
113       System.err.println("Prints a disassembled view of the given class.");
114       System.err.println("Usage: TraceClassVisitor <fully qualified class name>");
115       System.exit(-1);
116     }
117     ClassReader cr = new ClassReader(args[0]);
118     cr.accept(new TraceClassVisitor(null, new PrintWriter  (System.out)), true);
119   }
120 
121   /**
122    * Constructs a new {@link TraceClassVisitor TraceClassVisitor} object.
123    *
124    * @param cv the class visitor to which this adapter must delegate calls. May
125    *      be <tt>null</tt>.
126    * @param pw the print writer to be used to print the class.
127    */
128 
129   public TraceClassVisitor (final ClassVisitor cv, final PrintWriter   pw) {
130     super(pw);
131     this.cv = cv;
132   }
133 
134   public void visit (
135     final int access,
136     final String   name,
137     final String   superName,
138     final String  [] interfaces,
139     final String   sourceFile)
140   {
141     buf.setLength(0);
142     if ((access & Constants.ACC_DEPRECATED) != 0) {
143       buf.append("// DEPRECATED\n");
144     }
145     if (sourceFile != null) {
146       buf.append("// compiled from ").append(sourceFile).append("\n");
147     }
148     appendAccess(access & ~Constants.ACC_SUPER);
149     if ((access & Constants.ACC_INTERFACE) != 0) {
150       buf.append("interface ");
151     } else {
152       buf.append("class ");
153     }
154     buf.append(name).append(" ");
155     if (superName != null && !superName.equals("java/lang/Object")) {
156       buf.append("extends ").append(superName).append(" ");
157     }
158     if (interfaces != null && interfaces.length > 0) {
159       buf.append("implements ");
160       for (int i = 0; i < interfaces.length; ++i) {
161         buf.append(interfaces[i]).append(" ");
162       }
163     }
164     buf.append("{\n\n");
165     text.add(buf.toString());
166 
167     if (cv != null) {
168       cv.visit(access, name, superName, interfaces, sourceFile);
169     }
170   }
171 
172   public void visitInnerClass (
173     final String   name,
174     final String   outerName,
175     final String   innerName,
176     final int access)
177   {
178     buf.setLength(0);
179     buf.append("  INNERCLASS ")
180       .append(name)
181       .append(" ")
182       .append(outerName)
183       .append(" ")
184       .append(innerName)
185       .append(" ")
186       .append(access)
187       .append("\n");
188     text.add(buf.toString());
189 
190     if (cv != null) {
191       cv.visitInnerClass(name, outerName, innerName, access);
192     }
193   }
194 
195   public void visitField (
196     final int access,
197     final String   name,
198     final String   desc,
199     final Object   value,
200     final Attribute attrs)
201   {
202     buf.setLength(0);
203     if ((access & Constants.ACC_DEPRECATED) != 0) {
204       buf.append("  // DEPRECATED\n");
205     }
206     buf.append("  ");
207     appendAccess(access);
208     buf.append(desc)
209       .append(" ")
210       .append(name);
211     if (value != null) {
212       buf.append(" = ");
213       if (value instanceof String  ) {
214         buf.append("\"").append(value).append("\"");
215       } else {
216         buf.append(value);
217       }
218     }
219     Attribute attr = attrs;
220     while (attr != null) {
221       buf.append(" , FIELD ATTRIBUTE ").append(attr.type);
222       attr = attr.next;
223     }
224     buf.append("\n\n");
225     text.add(buf.toString());
226 
227     if (cv != null) {
228       cv.visitField(access, name, desc, value, attrs);
229     }
230   }
231 
232   public CodeVisitor visitMethod (
233     final int access,
234     final String   name,
235     final String   desc,
236     final String  [] exceptions,
237     final Attribute attrs)
238   {
239     buf.setLength(0);
240     if ((access & Constants.ACC_DEPRECATED) != 0) {
241       buf.append("  // DEPRECATED\n");
242     }
243     buf.append("  ");
244     appendAccess(access);
245     buf.append(name).
246       append(" ").
247       append(desc);
248     if (exceptions != null && exceptions.length > 0) {
249       buf.append(" throws ");
250       for (int i = 0; i < exceptions.length; ++i) {
251         buf.append(exceptions[i]).append(" ");
252       }
253     }
254     buf.append("\n");
255     text.add(buf.toString());
256     Attribute attr = attrs;
257     while (attr != null) {
258       buf.setLength(0);
259       buf.append("    METHOD ATTRIBUTE ")
260         .append(attr.type)
261         .append("\n");
262       text.add(buf.toString());
263       attr = attr.next;
264     }
265 
266     CodeVisitor cv;
267     if (this.cv != null) {
268       cv = this.cv.visitMethod(access, name, desc, exceptions, attrs);
269     } else {
270       cv = null;
271     }
272     PrintCodeVisitor pcv = new TraceCodeVisitor(cv);
273     text.add(pcv.getText());
274     return pcv;
275   }
276 
277   public void visitAttribute (final Attribute attr) {
278     buf.setLength(0);
279     buf.append("  CLASS ATTRIBUTE ")
280       .append(attr.type)
281       .append("\n");
282     text.add(buf.toString());
283 
284     if (cv != null) {
285       cv.visitAttribute(attr);
286     }
287   }
288 
289   public void visitEnd () {
290     text.add("}\n");
291 
292     if (cv != null) {
293       cv.visitEnd();
294     }
295 
296     super.visitEnd();
297   }
298 
299   /**
300    * Appends a string representation of the given access modifiers to {@link
301    * #buf buf}.
302    *
303    * @param access some access modifiers.
304    */
305 
306   private void appendAccess (final int access) {
307     if ((access & Constants.ACC_PUBLIC) != 0) {
308       buf.append("public ");
309     }
310     if ((access & Constants.ACC_PRIVATE) != 0) {
311       buf.append("private ");
312     }
313     if ((access & Constants.ACC_PROTECTED) != 0) {
314       buf.append("protected ");
315     }
316     if ((access & Constants.ACC_FINAL) != 0) {
317       buf.append("final ");
318     }
319     if ((access & Constants.ACC_STATIC) != 0) {
320       buf.append("static ");
321     }
322     if ((access & Constants.ACC_SYNCHRONIZED) != 0) {
323       buf.append("synchronized ");
324     }
325     if ((access & Constants.ACC_VOLATILE) != 0) {
326       buf.append("volatile ");
327     }
328     if ((access & Constants.ACC_TRANSIENT) != 0) {
329       buf.append("transient ");
330     }
331     if ((access & Constants.ACC_NATIVE) != 0) {
332       buf.append("native ");
333     }
334     if ((access & Constants.ACC_ABSTRACT) != 0) {
335       buf.append("abstract ");
336     }
337     if ((access & Constants.ACC_STRICT) != 0) {
338       buf.append("strictfp ");
339     }
340   }
341 }
342
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