Java > Open Source Codes > com > tc > 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 com.tc.asm.util;
31
32 import java.io.FileInputStream ;
33 import java.io.PrintWriter ;
34
35 import com.tc.asm.AnnotationVisitor;
36 import com.tc.asm.ClassReader;
37 import com.tc.asm.ClassVisitor;
38 import com.tc.asm.FieldVisitor;
39 import com.tc.asm.MethodVisitor;
40 import com.tc.asm.Opcodes;
41 import com.tc.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             return;
182         }
183         ClassReader cr;
184         if (args[i].endsWith(".class") || args[i].indexOf('\\') > -1
185                 || args[i].indexOf('/') > -1) {
186             cr = new ClassReader(new FileInputStream (args[i]));
187         } else {
188             cr = new ClassReader(args[i]);
189         }
190         cr.accept(new ASMifierClassVisitor(new PrintWriter (System.out)),
191                 getDefaultAttributes(),
192                 skipDebug);
193     }
194
195     /**
196      * Constructs a new {@link ASMifierClassVisitor} object.
197      *
198      * @param pw the print writer to be used to print the class.
199      */
200     public ASMifierClassVisitor(final PrintWriter pw) {
201         super("cw");
202         this.pw = pw;
203     }
204
205     // ------------------------------------------------------------------------
206 // Implementation of the ClassVisitor interface
207 // ------------------------------------------------------------------------
208
209     public void visit(
210         final int version,
211         final int access,
212         final String name,
213         final String signature,
214         final String superName,
215         final String [] interfaces)
216     {
217         String simpleName;
218         int n = name.lastIndexOf('/');
219         if (n != -1) {
220             text.add("package asm." + name.substring(0, n).replace('/', '.')
221                     + ";\n");
222             simpleName = name.substring(n + 1);
223         } else {
224             simpleName = name;
225         }
226         text.add("import java.util.*;\n");
227         text.add("import org.objectweb.asm.*;\n");
228         text.add("import org.objectweb.asm.attrs.*;\n");
229         text.add("public class " + simpleName + "Dump implements Opcodes {\n\n");
230         text.add("public static byte[] dump () throws Exception {\n\n");
231         text.add("ClassWriter cw = new ClassWriter(false);\n");
232         text.add("FieldVisitor fv;\n");
233         text.add("MethodVisitor mv;\n");
234         text.add("AnnotationVisitor av0;\n\n");
235
236         buf.setLength(0);
237         buf.append("cw.visit(");
238         switch (version) {
239             case Opcodes.V1_1:
240                 buf.append("V1_1");
241                 break;
242             case Opcodes.V1_2:
243                 buf.append("V1_2");
244                 break;
245             case Opcodes.V1_3:
246                 buf.append("V1_3");
247                 break;
248             case Opcodes.V1_4:
249                 buf.append("V1_4");
250                 break;
251             case Opcodes.V1_5:
252                 buf.append("V1_5");
253                 break;
254             case Opcodes.V1_6:
255                 buf.append("V1_6");
256                 break;
257             default:
258                 buf.append(version);
259                 break;
260         }
261         buf.append(", ");
262         appendAccess(access | ACCESS_CLASS);
263         buf.append(", ");
264         appendConstant(name);
265         buf.append(", ");
266         appendConstant(signature);
267         buf.append(", ");
268         appendConstant(superName);
269         buf.append(", ");
270         if (interfaces != null && interfaces.length > 0) {
271             buf.append("new String[] {");
272             for (int i = 0; i < interfaces.length; ++i) {
273                 buf.append(i == 0 ? " " : ", ");
274                 appendConstant(interfaces[i]);
275             }
276             buf.append(" }");
277         } else {
278             buf.append("null");
279         }
280         buf.append(");\n\n");
281         text.add(buf.toString());
282     }
283
284     public void visitSource(final String file, final String debug) {
285         buf.setLength(0);
286         buf.append("cw.visitSource(");
287         appendConstant(file);
288         buf.append(", ");
289         appendConstant(debug);
290         buf.append(");\n\n");
291         text.add(buf.toString());
292     }
293
294     public void visitOuterClass(
295         final String owner,
296         final String name,
297         final String desc)
298     {
299         buf.setLength(0);
300         buf.append("cw.visitOuterClass(");
301         appendConstant(owner);
302         buf.append(", ");
303         appendConstant(name);
304         buf.append(", ");
305         appendConstant(desc);
306         buf.append(");\n\n");
307         text.add(buf.toString());
308     }
309
310     public void visitInnerClass(
311         final String name,
312         final String outerName,
313         final String innerName,
314         final int access)
315     {
316         buf.setLength(0);
317         buf.append("cw.visitInnerClass(");
318         appendConstant(name);
319         buf.append(", ");
320         appendConstant(outerName);
321         buf.append(", ");
322         appendConstant(innerName);
323         buf.append(", ");
324         appendAccess(access | ACCESS_INNER);
325         buf.append(");\n\n");
326         text.add(buf.toString());
327     }
328
329     public FieldVisitor visitField(
330         final int access,
331         final String name,
332         final String desc,
333         final String signature,
334         final Object value)
335     {
336         buf.setLength(0);
337         buf.append("{\n");
338         buf.append("fv = cw.visitField(");
339         appendAccess(access | ACCESS_FIELD);
340         buf.append(", ");
341         appendConstant(name);
342         buf.append(", ");
343         appendConstant(desc);
344         buf.append(", ");
345         appendConstant(signature);
346         buf.append(", ");
347         appendConstant(value);
348         buf.append(");\n");
349         text.add(buf.toString());
350         ASMifierFieldVisitor aav = new ASMifierFieldVisitor();
351         text.add(aav.getText());
352         text.add("}\n");
353         return aav;
354     }
355
356     public MethodVisitor visitMethod(
357         final int access,
358         final String name,
359         final String desc,
360         final String signature,
361         final String [] exceptions)
362     {
363         buf.setLength(0);
364         buf.append("{\n");
365         buf.append("mv = cw.visitMethod(");
366         appendAccess(access);
367         buf.append(", ");
368         appendConstant(name);
369         buf.append(", ");
370         appendConstant(desc);
371         buf.append(", ");
372         appendConstant(signature);
373         buf.append(", ");
374         if (exceptions != null && exceptions.length > 0) {
375             buf.append("new String[] {");
376             for (int i = 0; i < exceptions.length; ++i) {
377                 buf.append(i == 0 ? " " : ", ");
378                 appendConstant(exceptions[i]);
379             }
380             buf.append(" }");
381         } else {
382             buf.append("null");
383         }
384         buf.append(");\n");
385         text.add(buf.toString());
386         ASMifierMethodVisitor acv = new ASMifierMethodVisitor();
387         text.add(acv.getText());
388         text.add("}\n");
389         return acv;
390     }
391
392     public AnnotationVisitor visitAnnotation(
393         final String desc,
394         final boolean visible)
395     {
396         buf.setLength(0);
397         buf.append("{\n");
398         buf.append("av0 = cw.visitAnnotation(");
399         appendConstant(desc);
400         buf.append(", ");
401         buf.append(visible);
402         buf.append(");\n");
403         text.add(buf.toString());
404         ASMifierAnnotationVisitor av = new ASMifierAnnotationVisitor(0);
405         text.add(av.getText());
406         text.add("}\n");
407         return av;
408     }
409
410     public void visitEnd() {
411         text.add("cw.visitEnd();\n\n");
412         text.add("return cw.toByteArray();\n");
413         text.add("}\n");
414         text.add("}\n");
415         printList(pw, text);
416         pw.flush();
417     }
418
419     // ------------------------------------------------------------------------
420 // Utility methods
421 // ------------------------------------------------------------------------
422
423     /**
424      * Appends a string representation of the given access modifiers to {@link
425      * #buf buf}.
426      *
427      * @param access some access modifiers.
428      */
429     void appendAccess(final int access) {
430         boolean first = true;
431         if ((access & Opcodes.ACC_PUBLIC) != 0) {
432             buf.append("ACC_PUBLIC");
433             first = false;
434         }
435         if ((access & Opcodes.ACC_PRIVATE) != 0) {
436             if (!first) {
437                 buf.append(" + ");
438             }
439             buf.append("ACC_PRIVATE");
440             first = false;
441         }
442         if ((access & Opcodes.ACC_PROTECTED) != 0) {
443             if (!first) {
444                 buf.append(" + ");
445             }
446             buf.append("ACC_PROTECTED");
447             first = false;
448         }
449         if ((access & Opcodes.ACC_FINAL) != 0) {
450             if (!first) {
451                 buf.append(" + ");
452             }
453             buf.append("ACC_FINAL");
454             first = false;
455         }
456         if ((access & Opcodes.ACC_STATIC) != 0) {
457             if (!first) {
458                 buf.append(" + ");
459             }
460             buf.append("ACC_STATIC");
461             first = false;
462         }
463         if ((access & Opcodes.ACC_SYNCHRONIZED) != 0) {
464             if (!first) {
465                 buf.append(" + ");
466             }
467             if ((access & ACCESS_CLASS) != 0) {
468                 buf.append("ACC_SUPER");
469             } else {
470                 buf.append("ACC_SYNCHRONIZED");
471             }
472             first = false;
473         }
474         if ((access & Opcodes.ACC_VOLATILE) != 0
475                 && (access & ACCESS_FIELD) != 0)
476         {
477             if (!first) {
478                 buf.append(" + ");
479             }
480             buf.append("ACC_VOLATILE");
481             first = false;
482         }
483         if ((access & Opcodes.ACC_BRIDGE) != 0 && (access & ACCESS_CLASS) == 0
484                 && (access & ACCESS_FIELD) == 0)
485         {
486             if (!first) {
487                 buf.append(" + ");
488             }
489             buf.append("ACC_BRIDGE");
490             first = false;
491         }
492         if ((access & Opcodes.ACC_VARARGS) != 0 && (access & ACCESS_CLASS) == 0
493                 && (access & ACCESS_FIELD) == 0)
494         {
495             if (!first) {
496                 buf.append(" + ");
497             }
498             buf.append("ACC_VARARGS");
499             first = false;
500         }
501         if ((access & Opcodes.ACC_TRANSIENT) != 0
502                 && (access & ACCESS_FIELD) != 0)
503         {
504             if (!first) {
505                 buf.append(" + ");
506             }
507             buf.append("ACC_TRANSIENT");
508             first = false;
509         }
510         if ((access & Opcodes.ACC_NATIVE) != 0 && (access & ACCESS_CLASS) == 0
511                 && (access & ACCESS_FIELD) == 0)
512         {
513             if (!first) {
514                 buf.append(" + ");
515             }
516             buf.append("ACC_NATIVE");
517             first = false;
518         }
519         if ((access & Opcodes.ACC_ENUM) != 0
520                 && ((access & ACCESS_CLASS) != 0
521                         || (access & ACCESS_FIELD) != 0 || (access & ACCESS_INNER) != 0))
522         {
523             if (!first) {
524                 buf.append(" + ");
525             }
526             buf.append("ACC_ENUM");
527             first = false;
528         }
529         if ((access & Opcodes.ACC_ANNOTATION) != 0
530                 && ((access & ACCESS_CLASS) != 0))
531         {
532             if (!first) {
533                 buf.append(" + ");
534             }
535             buf.append("ACC_ANNOTATION");
536             first = false;
537         }
538         if ((access & Opcodes.ACC_ABSTRACT) != 0) {
539             if (!first) {
540                 buf.append(" + ");
541             }
542             buf.append("ACC_ABSTRACT");
543             first = false;
544         }
545         if ((access & Opcodes.ACC_INTERFACE) != 0) {
546             if (!first) {
547                 buf.append(" + ");
548             }
549             buf.append("ACC_INTERFACE");
550             first = false;
551         }
552         if ((access & Opcodes.ACC_STRICT) != 0) {
553             if (!first) {
554                 buf.append(" + ");
555             }
556             buf.append("ACC_STRICT");
557             first = false;
558         }
559         if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
560             if (!first) {
561                 buf.append(" + ");
562             }
563             buf.append("ACC_SYNTHETIC");
564             first = false;
565         }
566         if ((access & Opcodes.ACC_DEPRECATED) != 0) {
567             if (!first) {
568                 buf.append(" + ");
569             }
570             buf.append("ACC_DEPRECATED");
571             first = false;
572         }
573         if (first) {
574             buf.append("0");
575         }
576     }
577
578     /**
579      * Appends a string representation of the given constant to the given
580      * buffer.
581      *
582      * @param buf a string buffer.
583      * @param cst an {@link java.lang.Integer Integer}, {@link java.lang.Float
584      * Float}, {@link java.lang.Long Long},
585      * {@link java.lang.Double Double} or {@link String String} object.
586      * May be <tt>null</tt>.
587      */
588     static void appendConstant(final StringBuffer buf, final Object cst) {
589         if (cst == null) {
590             buf.append("null");
591         } else if (cst instanceof String ) {
592             AbstractVisitor.appendString(buf, (String ) cst);
593         } else if (cst instanceof Type) {
594             buf.append("Type.getType(\"")
595                     .append(((Type) cst).getDescriptor())
596                     .append("\")");
597         } else if (cst instanceof Integer ) {
598             buf.append("new Integer(").append(cst).append(")");
599         } else if (cst instanceof Float ) {
600             buf.append("new Float(\"").append(cst).append("\")");
601         } else if (cst instanceof Long ) {
602             buf.append("new Long(").append(cst).append("L)");
603         } else if (cst instanceof Double ) {
604             buf.append("new Double(\"").append(cst).append("\")");
605         }
606     }
607 }
608

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