Java > Open Source Codes > org > objectweb > asm > util > ASMifierClassVisitor


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 org.objectweb.asm.util;
31
32 import java.io.FileInputStream ;
33 import java.io.PrintWriter ;
34
35 import org.objectweb.asm.AnnotationVisitor;
36 import org.objectweb.asm.ClassReader;
37 import org.objectweb.asm.ClassVisitor;
38 import org.objectweb.asm.FieldVisitor;
39 import org.objectweb.asm.MethodVisitor;
40 import org.objectweb.asm.Opcodes;
41 import org.objectweb.asm.Type;
42
43 /**
44  * A {@link ClassVisitor} that prints the ASM code that generates the classes it
45  * visits. This class visitor can be used to quickly write ASM code to generate
46  * some given bytecode: <ul> <li>write the Java source code equivalent to the
47  * bytecode you want to generate;</li> <li>compile it with <tt>javac</tt>;</li>
48  * <li>make a {@link ASMifierClassVisitor} visit this compiled class (see the
49  * {@link #main main} method);</li> <li>edit the generated source code, if
50  * necessary.</li> </ul> The source code printed when visiting the
51  * <tt>Hello</tt> class is the following: <p> <blockquote>
52  *
53  * <pre>
54  * import org.objectweb.asm.*;
55  *
56  * public class HelloDump implements Opcodes {
57  *
58  * public static byte[] dump() throws Exception {
59  *
60  * ClassWriter cw = new ClassWriter(false);
61  * FieldVisitor fv;
62  * MethodVisitor mv;
63  * AnnotationVisitor av0;
64  *
65  * cw.visit(49,
66  * ACC_PUBLIC + ACC_SUPER,
67  * &quot;Hello&quot;,
68  * null,
69  * &quot;java/lang/Object&quot;,
70  * null);
71  *
72  * cw.visitSource(&quot;Hello.java&quot;, null);
73  *
74  * {
75  * mv = cw.visitMethod(ACC_PUBLIC, &quot;&lt;init&gt;&quot;, &quot;()V&quot;, null, null);
76  * mv.visitVarInsn(ALOAD, 0);
77  * mv.visitMethodInsn(INVOKESPECIAL,
78  * &quot;java/lang/Object&quot;,
79  * &quot;&lt;init&gt;&quot;,
80  * &quot;()V&quot;);
81  * mv.visitInsn(RETURN);
82  * mv.visitMaxs(1, 1);
83  * mv.visitEnd();
84  * }
85  * {
86  * mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC,
87  * &quot;main&quot;,
88  * &quot;([Ljava/lang/String;)V&quot;,
89  * null,
90  * null);
91  * mv.visitFieldInsn(GETSTATIC,
92  * &quot;java/lang/System&quot;,
93  * &quot;out&quot;,
94  * &quot;Ljava/io/PrintStream;&quot;);
95  * mv.visitLdcInsn(&quot;hello&quot;);
96  * mv.visitMethodInsn(INVOKEVIRTUAL,
97  * &quot;java/io/PrintStream&quot;,
98  * &quot;println&quot;,
99  * &quot;(Ljava/lang/String;)V&quot;);
100  * mv.visitInsn(RETURN);
101  * mv.visitMaxs(2, 1);
102  * mv.visitEnd();
103  * }
104  * cw.visitEnd();
105  *
106  * return cw.toByteArray();
107  * }
108  * }
109  *
110  * </pre>
111  *
112  * </blockquote> where <tt>Hello</tt> is defined by: <p> <blockquote>
113  *
114  * <pre>
115  * public class Hello {
116  *
117  * public static void main(String[] args) {
118  * System.out.println(&quot;hello&quot;);
119  * }
120  * }
121  * </pre>
122  *
123  * </blockquote>
124  *
125  * @author Eric Bruneton
126  * @author Eugene Kuleshov
127  */
128 public class ASMifierClassVisitor extends ASMifierAbstractVisitor implements
129         ClassVisitor
130 {
131
132     /**
133      * Pseudo access flag used to distinguish class access flags.
134      */
135     private final static int ACCESS_CLASS = 262144;
136
137     /**
138      * Pseudo access flag used to distinguish field access flags.
139      */
140     private final static int ACCESS_FIELD = 524288;
141
142     /**
143      * Pseudo access flag used to distinguish inner class flags.
144      */
145     private static final int ACCESS_INNER = 1048576;
146
147     /**
148      * The print writer to be used to print the class.
149      */
150     protected final PrintWriter pw;
151
152     /**
153      * Prints the ASM source code to generate the given class to the standard
154      * output. <p> Usage: ASMifierClassVisitor [-debug] &lt;fully qualified
155      * class name or class file name&gt;
156      *
157      * @param args the command line arguments.
158      *
159      * @throws Exception if the class cannot be found, or if an IO exception
160      * occurs.
161      */
162     public static void main(final String [] args) throws Exception {
163         int i = 0;
164         boolean skipDebug = true;
165
166         boolean ok = true;
167         if (args.length < 1 || args.length > 2) {
168             ok = false;
169         }
170         if (ok && args[0].equals("-debug")) {
171             i = 1;
172             skipDebug = false;
173             if (args.length != 2) {
174                 ok = false;
175             }
176         }
177         if (!ok) {
178             System.err.println("Prints the ASM code to generate the given class.");
179             System.err.println("Usage: ASMifierClassVisitor [-debug] "
180                     + "<fully qualified class name or class file name>");
181             System.exit(-1);
182         }
183         ClassReader cr;
184         if (args[i].endsWith(".class")) {
185             cr = new ClassReader(new FileInputStream (args[i]));
186         } else {
187             cr = new ClassReader(args[i]);
188         }
189         cr.accept(new ASMifierClassVisitor(new PrintWriter (System.out)),
190                 getDefaultAttributes(),
191                 skipDebug);
192     }
193
194     /**
195      * Constructs a new {@link ASMifierClassVisitor} object.
196      *
197      * @param pw the print writer to be used to print the class.
198      */
199     public ASMifierClassVisitor(final PrintWriter pw) {
200         super("cw");
201         this.pw = pw;
202     }
203
204     // ------------------------------------------------------------------------
205 // Implementation of the ClassVisitor interface
206 // ------------------------------------------------------------------------
207
208     public void visit(
209         final int version,
210         final int access,
211         final String name,
212         final String signature,
213         final String superName,
214         final String [] interfaces)
215     {
216         String simpleName;
217         int n = name.lastIndexOf('/');
218         if (n != -1) {
219             text.add("package asm." + name.substring(0, n).replace('/', '.')
220                     + ";\n");
221             simpleName = name.substring(n + 1);
222         } else {
223             simpleName = name;
224         }
225         text.add("import java.util.*;\n");
226         text.add("import org.objectweb.asm.*;\n");
227         text.add("import org.objectweb.asm.attrs.*;\n");
228         text.add("public class " + simpleName + "Dump implements Opcodes {\n\n");
229         text.add("public static byte[] dump () throws Exception {\n\n");
230         text.add("ClassWriter cw = new ClassWriter(false);\n");
231         text.add("FieldVisitor fv;\n");
232         text.add("MethodVisitor mv;\n");
233         text.add("AnnotationVisitor av0;\n\n");
234
235         buf.setLength(0);
236         buf.append("cw.visit(");
237         switch (version) {
238             case Opcodes.V1_1:
239                 buf.append("V1_1");
240                 break;
241             case Opcodes.V1_2:
242                 buf.append("V1_2");
243                 break;
244             case Opcodes.V1_3:
245                 buf.append("V1_3");
246                 break;
247             case Opcodes.V1_4:
248                 buf.append("V1_4");
249                 break;
250             case Opcodes.V1_5:
251                 buf.append("V1_5");
252                 break;
253             case Opcodes.V1_6:
254                 buf.append("V1_6");
255                 break;
256             default:
257                 buf.append(version);
258                 break;
259         }
260         buf.append(", ");
261         appendAccess(access | ACCESS_CLASS);
262         buf.append(", ");
263         appendConstant(name);
264         buf.append(", ");
265         appendConstant(signature);
266         buf.append(", ");
267         appendConstant(superName);
268         buf.append(", ");
269         if (interfaces != null && interfaces.length > 0) {
270             buf.append("new String[] {");
271             for (int i = 0; i < interfaces.length; ++i) {
272                 buf.append(i == 0 ? " " : ", ");
273                 appendConstant(interfaces[i]);
274             }
275             buf.append(" }");
276         } else {
277             buf.append("null");
278         }
279         buf.append(");\n\n");
280         text.add(buf.toString());
281     }
282
283     public void visitSource(final String file, final String debug) {
284         buf.setLength(0);
285         buf.append("cw.visitSource(");
286         appendConstant(file);
287         buf.append(", ");
288         appendConstant(debug);
289         buf.append(");\n\n");
290         text.add(buf.toString());
291     }
292
293     public void visitOuterClass(
294         final String owner,
295         final String name,
296         final String desc)
297     {
298         buf.setLength(0);
299         buf.append("cw.visitOuterClass(");
300         appendConstant(owner);
301         buf.append(", ");
302         appendConstant(name);
303         buf.append(", ");
304         appendConstant(desc);
305         buf.append(");\n\n");
306         text.add(buf.toString());
307     }
308
309     public void visitInnerClass(
310         final String name,
311         final String outerName,
312         final String innerName,
313         final int access)
314     {
315         buf.setLength(0);
316         buf.append("cw.visitInnerClass(");
317         appendConstant(name);
318         buf.append(", ");
319         appendConstant(outerName);
320         buf.append(", ");
321         appendConstant(innerName);
322         buf.append(", ");
323         appendAccess(access | ACCESS_INNER);
324         buf.append(");\n\n");
325         text.add(buf.toString());
326     }
327
328     public FieldVisitor visitField(
329         final int access,
330         final String name,
331         final String desc,
332         final String signature,
333         final Object value)
334     {
335         buf.setLength(0);
336         buf.append("{\n");
337         buf.append("fv = cw.visitField(");
338         appendAccess(access | ACCESS_FIELD);
339         buf.append(", ");
340         appendConstant(name);
341         buf.append(", ");
342         appendConstant(desc);
343         buf.append(", ");
344         appendConstant(signature);
345         buf.append(", ");
346         appendConstant(value);
347         buf.append(");\n");
348         text.add(buf.toString());
349         ASMifierFieldVisitor aav = new ASMifierFieldVisitor();
350         text.add(aav.getText());
351         text.add("}\n");
352         return aav;
353     }
354
355     public MethodVisitor visitMethod(
356         final int access,
357         final String name,
358         final String desc,
359         final String signature,
360         final String [] exceptions)
361     {
362         buf.setLength(0);
363         buf.append("{\n");
364         buf.append("mv = cw.visitMethod(");
365         appendAccess(access);
366         buf.append(", ");
367         appendConstant(name);
368         buf.append(", ");
369         appendConstant(desc);
370         buf.append(", ");
371         appendConstant(signature);
372         buf.append(", ");
373         if (exceptions != null && exceptions.length > 0) {
374             buf.append("new String[] {");
375             for (int i = 0; i < exceptions.length; ++i) {
376                 buf.append(i == 0 ? " " : ", ");
377                 appendConstant(exceptions[i]);
378             }
379             buf.append(" }");
380         } else {
381             buf.append("null");
382         }
383         buf.append(");\n");
384         text.add(buf.toString());
385         ASMifierMethodVisitor acv = new ASMifierMethodVisitor();
386         text.add(acv.getText());
387         text.add("}\n");
388         return acv;
389     }
390
391     public AnnotationVisitor visitAnnotation(
392         final String desc,
393         final boolean visible)
394     {
395         buf.setLength(0);
396         buf.append("{\n");
397         buf.append("av0 = cw.visitAnnotation(");
398         appendConstant(desc);
399         buf.append(", ");
400         buf.append(visible);
401         buf.append(");\n");
402         text.add(buf.toString());
403         ASMifierAnnotationVisitor av = new ASMifierAnnotationVisitor(0);
404         text.add(av.getText());
405         text.add("}\n");
406         return av;
407     }
408
409     public void visitEnd() {
410         text.add("cw.visitEnd();\n\n");
411         text.add("return cw.toByteArray();\n");
412         text.add("}\n");
413         text.add("}\n");
414         printList(pw, text);
415         pw.flush();
416     }
417
418     // ------------------------------------------------------------------------
419 // Utility methods
420 // ------------------------------------------------------------------------
421
422     /**
423      * Appends a string representation of the given access modifiers to {@link
424      * #buf buf}.
425      *
426      * @param access some access modifiers.
427      */
428     void appendAccess(final int access) {
429         boolean first = true;
430         if ((access & Opcodes.ACC_PUBLIC) != 0) {
431             buf.append("ACC_PUBLIC");
432             first = false;
433         }
434         if ((access & Opcodes.ACC_PRIVATE) != 0) {
435             if (!first) {
436                 buf.append(" + ");
437             }
438             buf.append("ACC_PRIVATE");
439             first = false;
440         }
441         if ((access & Opcodes.ACC_PROTECTED) != 0) {
442             if (!first) {
443                 buf.append(" + ");
444             }
445             buf.append("ACC_PROTECTED");
446             first = false;
447         }
448         if ((access & Opcodes.ACC_FINAL) != 0) {
449             if (!first) {
450                 buf.append(" + ");
451             }
452             buf.append("ACC_FINAL");
453             first = false;
454         }
455         if ((access & Opcodes.ACC_STATIC) != 0) {
456             if (!first) {
457                 buf.append(" + ");
458             }
459             buf.append("ACC_STATIC");
460             first = false;
461         }
462         if ((access & Opcodes.ACC_SYNCHRONIZED) != 0) {
463             if (!first) {
464                 buf.append(" + ");
465             }
466             if ((access & ACCESS_CLASS) != 0) {
467                 buf.append("ACC_SUPER");
468             } else {
469                 buf.append("ACC_SYNCHRONIZED");
470             }
471             first = false;
472         }
473         if ((access & Opcodes.ACC_VOLATILE) != 0
474                 && (access & ACCESS_FIELD) != 0)
475         {
476             if (!first) {
477                 buf.append(" + ");
478             }
479             buf.append("ACC_VOLATILE");
480             first = false;
481         }
482         if ((access & Opcodes.ACC_BRIDGE) != 0 && (access & ACCESS_CLASS) == 0
483                 && (access & ACCESS_FIELD) == 0)
484         {
485             if (!first) {
486                 buf.append(" + ");
487             }
488             buf.append("ACC_BRIDGE");
489             first = false;
490         }
491         if ((access & Opcodes.ACC_VARARGS) != 0 && (access & ACCESS_CLASS) == 0
492                 && (access & ACCESS_FIELD) == 0)
493         {
494             if (!first) {
495                 buf.append(" + ");
496             }
497             buf.append("ACC_VARARGS");
498             first = false;
499         }
500         if ((access & Opcodes.ACC_TRANSIENT) != 0
501                 && (access & ACCESS_FIELD) != 0)
502         {
503             if (!first) {
504                 buf.append(" + ");
505             }
506             buf.append("ACC_TRANSIENT");
507             first = false;
508         }
509         if ((access & Opcodes.ACC_NATIVE) != 0 && (access & ACCESS_CLASS) == 0
510                 && (access & ACCESS_FIELD) == 0)
511         {
512             if (!first) {
513                 buf.append(" + ");
514             }
515             buf.append("ACC_NATIVE");
516             first = false;
517         }
518         if ((access & Opcodes.ACC_ENUM) != 0
519                 && ((access & ACCESS_CLASS) != 0
520                         || (access & ACCESS_FIELD) != 0 || (access & ACCESS_INNER) != 0))
521         {
522             if (!first) {
523                 buf.append(" + ");
524             }
525             buf.append("ACC_ENUM");
526             first = false;
527         }
528         if ((access & Opcodes.ACC_ANNOTATION) != 0
529                 && ((access & ACCESS_CLASS) != 0))
530         {
531             if (!first) {
532                 buf.append(" + ");
533             }
534             buf.append("ACC_ANNOTATION");
535             first = false;
536         }
537         if ((access & Opcodes.ACC_ABSTRACT) != 0) {
538             if (!first) {
539                 buf.append(" + ");
540             }
541             buf.append("ACC_ABSTRACT");
542             first = false;
543         }
544         if ((access & Opcodes.ACC_INTERFACE) != 0) {
545             if (!first) {
546                 buf.append(" + ");
547             }
548             buf.append("ACC_INTERFACE");
549             first = false;
550         }
551         if ((access & Opcodes.ACC_STRICT) != 0) {
552             if (!first) {
553                 buf.append(" + ");
554             }
555             buf.append("ACC_STRICT");
556             first = false;
557         }
558         if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
559             if (!first) {
560                 buf.append(" + ");
561             }
562             buf.append("ACC_SYNTHETIC");
563             first = false;
564         }
565         if ((access & Opcodes.ACC_DEPRECATED) != 0) {
566             if (!first) {
567                 buf.append(" + ");
568             }
569             buf.append("ACC_DEPRECATED");
570             first = false;
571         }
572         if (first) {
573             buf.append("0");
574         }
575     }
576
577     /**
578      * Appends a string representation of the given constant to the given
579      * buffer.
580      *
581      * @param buf a string buffer.
582      * @param cst an {@link java.lang.Integer Integer}, {@link java.lang.Float
583      * Float}, {@link java.lang.Long Long},
584      * {@link java.lang.Double Double} or {@link String String} object.
585      * May be <tt>null</tt>.
586      */
587     static void appendConstant(final StringBuffer buf, final Object cst) {
588         if (cst == null) {
589             buf.append("null");
590         } else if (cst instanceof String ) {
591             AbstractVisitor.appendString(buf, (String ) cst);
592         } else if (cst instanceof Type) {
593             buf.append("Type.getType(\"")
594                     .append(((Type) cst).getDescriptor())
595                     .append("\")");
596         } else if (cst instanceof Integer ) {
597             buf.append("new Integer(").append(cst).append(")");
598         } else if (cst instanceof Float ) {
599             buf.append("new Float(\"").append(cst).append("\")");
600         } else if (cst instanceof Long ) {
601             buf.append("new Long(").append(cst).append("L)");
602         } else if (cst instanceof Double ) {
603             buf.append("new Double(\"").append(cst).append("\")");
604         }
605     }
606 }
607

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