Java > Open Source Codes > org > objectweb > asm > ClassWriter


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;
31
32 /**
33  * A {@link ClassVisitor} that generates classes in bytecode form. More
34  * precisely this visitor generates a byte array conforming to the Java class
35  * file format. It can be used alone, to generate a Java class "from scratch",
36  * or with one or more {@link ClassReader ClassReader} and adapter class visitor
37  * to generate a modified class from one or more existing Java classes.
38  *
39  * @author Eric Bruneton
40  */
41 public class ClassWriter implements ClassVisitor {
42
43     /**
44      * The type of instructions without any argument.
45      */
46     final static int NOARG_INSN = 0;
47
48     /**
49      * The type of instructions with an signed byte argument.
50      */
51     final static int SBYTE_INSN = 1;
52
53     /**
54      * The type of instructions with an signed short argument.
55      */
56     final static int SHORT_INSN = 2;
57
58     /**
59      * The type of instructions with a local variable index argument.
60      */
61     final static int VAR_INSN = 3;
62
63     /**
64      * The type of instructions with an implicit local variable index argument.
65      */
66     final static int IMPLVAR_INSN = 4;
67
68     /**
69      * The type of instructions with a type descriptor argument.
70      */
71     final static int TYPE_INSN = 5;
72
73     /**
74      * The type of field and method invocations instructions.
75      */
76     final static int FIELDORMETH_INSN = 6;
77
78     /**
79      * The type of the INVOKEINTERFACE instruction.
80      */
81     final static int ITFMETH_INSN = 7;
82
83     /**
84      * The type of instructions with a 2 bytes bytecode offset label.
85      */
86     final static int LABEL_INSN = 8;
87
88     /**
89      * The type of instructions with a 4 bytes bytecode offset label.
90      */
91     final static int LABELW_INSN = 9;
92
93     /**
94      * The type of the LDC instruction.
95      */
96     final static int LDC_INSN = 10;
97
98     /**
99      * The type of the LDC_W and LDC2_W instructions.
100      */
101     final static int LDCW_INSN = 11;
102
103     /**
104      * The type of the IINC instruction.
105      */
106     final static int IINC_INSN = 12;
107
108     /**
109      * The type of the TABLESWITCH instruction.
110      */
111     final static int TABL_INSN = 13;
112
113     /**
114      * The type of the LOOKUPSWITCH instruction.
115      */
116     final static int LOOK_INSN = 14;
117
118     /**
119      * The type of the MULTIANEWARRAY instruction.
120      */
121     final static int MANA_INSN = 15;
122
123     /**
124      * The type of the WIDE instruction.
125      */
126     final static int WIDE_INSN = 16;
127
128     /**
129      * The instruction types of all JVM opcodes.
130      */
131     static byte[] TYPE;
132
133     /**
134      * The type of CONSTANT_Class constant pool items.
135      */
136     final static int CLASS = 7;
137
138     /**
139      * The type of CONSTANT_Fieldref constant pool items.
140      */
141     final static int FIELD = 9;
142
143     /**
144      * The type of CONSTANT_Methodref constant pool items.
145      */
146     final static int METH = 10;
147
148     /**
149      * The type of CONSTANT_InterfaceMethodref constant pool items.
150      */
151     final static int IMETH = 11;
152
153     /**
154      * The type of CONSTANT_String constant pool items.
155      */
156     final static int STR = 8;
157
158     /**
159      * The type of CONSTANT_Integer constant pool items.
160      */
161     final static int INT = 3;
162
163     /**
164      * The type of CONSTANT_Float constant pool items.
165      */
166     final static int FLOAT = 4;
167
168     /**
169      * The type of CONSTANT_Long constant pool items.
170      */
171     final static int LONG = 5;
172
173     /**
174      * The type of CONSTANT_Double constant pool items.
175      */
176     final static int DOUBLE = 6;
177
178     /**
179      * The type of CONSTANT_NameAndType constant pool items.
180      */
181     final static int NAME_TYPE = 12;
182
183     /**
184      * The type of CONSTANT_Utf8 constant pool items.
185      */
186     final static int UTF8 = 1;
187
188     /**
189      * Minor and major version numbers of the class to be generated.
190      */
191     int version;
192
193     /**
194      * Index of the next item to be added in the constant pool.
195      */
196     private short index;
197
198     /**
199      * The constant pool of this class.
200      */
201     private ByteVector pool;
202
203     /**
204      * The constant pool's hash table data.
205      */
206     private Item[] items;
207
208     /**
209      * The threshold of the constant pool's hash table.
210      */
211     private int threshold;
212
213     /**
214      * A reusable key used to look for items in the hash {@link #items items}.
215      */
216     Item key;
217
218     /**
219      * A reusable key used to look for items in the hash {@link #items items}.
220      */
221     Item key2;
222
223     /**
224      * A reusable key used to look for items in the hash {@link #items items}.
225      */
226     Item key3;
227
228     /**
229      * The access flags of this class.
230      */
231     private int access;
232
233     /**
234      * The constant pool item that contains the internal name of this class.
235      */
236     private int name;
237
238     /**
239      * The constant pool item that contains the signature of this class.
240      */
241     private int signature;
242
243     /**
244      * The constant pool item that contains the internal name of the super class
245      * of this class.
246      */
247     private int superName;
248
249     /**
250      * Number of interfaces implemented or extended by this class or interface.
251      */
252     private int interfaceCount;
253
254     /**
255      * The interfaces implemented or extended by this class or interface. More
256      * precisely, this array contains the indexes of the constant pool items
257      * that contain the internal names of these interfaces.
258      */
259     private int[] interfaces;
260
261     /**
262      * The index of the constant pool item that contains the name of the source
263      * file from which this class was compiled.
264      */
265     private int sourceFile;
266
267     /**
268      * The SourceDebug attribute of this class.
269      */
270     private ByteVector sourceDebug;
271
272     /**
273      * The constant pool item that contains the name of the enclosing class of
274      * this class.
275      */
276     private int enclosingMethodOwner;
277
278     /**
279      * The constant pool item that contains the name and descriptor of the
280      * enclosing method of this class.
281      */
282     private int enclosingMethod;
283
284     /**
285      * The runtime visible annotations of this class.
286      */
287     private AnnotationWriter anns;
288
289     /**
290      * The runtime invisible annotations of this class.
291      */
292     private AnnotationWriter ianns;
293
294     /**
295      * The non standard attributes of this class.
296      */
297     private Attribute attrs;
298
299     /**
300      * The number of entries in the InnerClasses attribute.
301      */
302     private int innerClassesCount;
303
304     /**
305      * The InnerClasses attribute.
306      */
307     private ByteVector innerClasses;
308
309     /**
310      * The fields of this class. These fields are stored in a linked list of
311      * {@link FieldWriter} objects, linked to each other by their
312      * {@link FieldWriter#next} field. This field stores the first element of
313      * this list.
314      */
315     FieldWriter firstField;
316
317     /**
318      * The fields of this class. These fields are stored in a linked list of
319      * {@link FieldWriter} objects, linked to each other by their
320      * {@link FieldWriter#next} field. This field stores the last element of
321      * this list.
322      */
323     FieldWriter lastField;
324
325     /**
326      * The methods of this class. These methods are stored in a linked list of
327      * {@link MethodWriter} objects, linked to each other by their
328      * {@link MethodWriter#next} field. This field stores the first element of
329      * this list.
330      */
331     MethodWriter firstMethod;
332
333     /**
334      * The methods of this class. These methods are stored in a linked list of
335      * {@link MethodWriter} objects, linked to each other by their
336      * {@link MethodWriter#next} field. This field stores the last element of
337      * this list.
338      */
339     MethodWriter lastMethod;
340
341     /**
342      * <tt>true</tt> if the maximum stack size and number of local variables
343      * must be automatically computed.
344      */
345     private boolean computeMaxs;
346
347     /**
348      * <tt>true</tt> to test that all attributes are known.
349      */
350     boolean checkAttributes;
351
352     // ------------------------------------------------------------------------
353 // Static initializer
354 // ------------------------------------------------------------------------
355
356     /**
357      * Computes the instruction types of JVM opcodes.
358      */
359     static {
360         int i;
361         byte[] b = new byte[220];
362         String s = "AAAAAAAAAAAAAAAABCKLLDDDDDEEEEEEEEEEEEEEEEEEEEAAAAAAAADD"
363                 + "DDDEEEEEEEEEEEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
364                 + "AAAAAAAAAAAAAAAAAMAAAAAAAAAAAAAAAAAAAAIIIIIIIIIIIIIIIIDNOAA"
365                 + "AAAAGGGGGGGHAFBFAAFFAAQPIIJJIIIIIIIIIIIIIIIIII";
366         for (i = 0; i < b.length; ++i) {
367             b[i] = (byte) (s.charAt(i) - 'A');
368         }
369         TYPE = b;
370
371         // code to generate the above string
372 //
373 // // SBYTE_INSN instructions
374 // b[Constants.NEWARRAY] = SBYTE_INSN;
375 // b[Constants.BIPUSH] = SBYTE_INSN;
376 //
377 // // SHORT_INSN instructions
378 // b[Constants.SIPUSH] = SHORT_INSN;
379 //
380 // // (IMPL)VAR_INSN instructions
381 // b[Constants.RET] = VAR_INSN;
382 // for (i = Constants.ILOAD; i <= Constants.ALOAD; ++i) {
383 // b[i] = VAR_INSN;
384 // }
385 // for (i = Constants.ISTORE; i <= Constants.ASTORE; ++i) {
386 // b[i] = VAR_INSN;
387 // }
388 // for (i = 26; i <= 45; ++i) { // ILOAD_0 to ALOAD_3
389 // b[i] = IMPLVAR_INSN;
390 // }
391 // for (i = 59; i <= 78; ++i) { // ISTORE_0 to ASTORE_3
392 // b[i] = IMPLVAR_INSN;
393 // }
394 //
395 // // TYPE_INSN instructions
396 // b[Constants.NEW] = TYPE_INSN;
397 // b[Constants.ANEWARRAY] = TYPE_INSN;
398 // b[Constants.CHECKCAST] = TYPE_INSN;
399 // b[Constants.INSTANCEOF] = TYPE_INSN;
400 //
401 // // (Set)FIELDORMETH_INSN instructions
402 // for (i = Constants.GETSTATIC; i <= Constants.INVOKESTATIC; ++i) {
403 // b[i] = FIELDORMETH_INSN;
404 // }
405 // b[Constants.INVOKEINTERFACE] = ITFMETH_INSN;
406 //
407 // // LABEL(W)_INSN instructions
408 // for (i = Constants.IFEQ; i <= Constants.JSR; ++i) {
409 // b[i] = LABEL_INSN;
410 // }
411 // b[Constants.IFNULL] = LABEL_INSN;
412 // b[Constants.IFNONNULL] = LABEL_INSN;
413 // b[200] = LABELW_INSN; // GOTO_W
414 // b[201] = LABELW_INSN; // JSR_W
415 // // temporary opcodes used internally by ASM - see Label and
416 // MethodWriter
417 // for (i = 202; i < 220; ++i) {
418 // b[i] = LABEL_INSN;
419 // }
420 //
421 // // LDC(_W) instructions
422 // b[Constants.LDC] = LDC_INSN;
423 // b[19] = LDCW_INSN; // LDC_W
424 // b[20] = LDCW_INSN; // LDC2_W
425 //
426 // // special instructions
427 // b[Constants.IINC] = IINC_INSN;
428 // b[Constants.TABLESWITCH] = TABL_INSN;
429 // b[Constants.LOOKUPSWITCH] = LOOK_INSN;
430 // b[Constants.MULTIANEWARRAY] = MANA_INSN;
431 // b[196] = WIDE_INSN; // WIDE
432 //
433 // for (i = 0; i < b.length; ++i) {
434 // System.err.print((char)('A' + b[i]));
435 // }
436 // System.err.println();
437 }
438
439     // ------------------------------------------------------------------------
440 // Constructor
441 // ------------------------------------------------------------------------
442
443     /**
444      * Constructs a new {@link ClassWriter ClassWriter} object.
445      *
446      * @param computeMaxs <tt>true</tt> if the maximum stack size and the
447      * maximum number of local variables must be automatically computed.
448      * If this flag is <tt>true</tt>, then the arguments of the
449      * {@link MethodVisitor#visitMaxs visitMaxs} method of the
450      * {@link MethodVisitor} returned by the
451      * {@link #visitMethod visitMethod} method will be ignored, and
452      * computed automatically from the signature and the bytecode of each
453      * method.
454      */
455     public ClassWriter(final boolean computeMaxs) {
456         this(computeMaxs, false);
457     }
458
459     /**
460      * Constructs a new {@link ClassWriter} object.
461      *
462      * @param computeMaxs <tt>true</tt> if the maximum stack size and the
463      * maximum number of local variables must be automatically computed.
464      * If this flag is <tt>true</tt>, then the arguments of the
465      * {@link MethodVisitor#visitMaxs visitMaxs} method of the
466      * {@link MethodVisitor} returned by the
467      * {@link #visitMethod visitMethod} method will be ignored, and
468      * computed automatically from the signature and the bytecode of each
469      * method.
470      * @param skipUnknownAttributes <tt>true</tt> to silently ignore unknown
471      * attributes, or <tt>false</tt> to throw an exception if an
472      * unknown attribute is found.
473      */
474     public ClassWriter(
475         final boolean computeMaxs,
476         final boolean skipUnknownAttributes)
477     {
478         index = 1;
479         pool = new ByteVector();
480         items = new Item[256];
481         threshold = (int) (0.75d * items.length);
482         key = new Item();
483         key2 = new Item();
484         key3 = new Item();
485         this.computeMaxs = computeMaxs;
486         this.checkAttributes = !skipUnknownAttributes;
487     }
488
489     // ------------------------------------------------------------------------
490 // Implementation of the ClassVisitor interface
491 // ------------------------------------------------------------------------
492
493     public void visit(
494         final int version,
495         final int access,
496         final String name,
497         final String signature,
498         final String superName,
499         final String [] interfaces)
500     {
501         this.version = version;
502         this.access = access;
503         this.name = newClass(name);
504         if (signature != null) {
505             this.signature = newUTF8(signature);
506         }
507         this.superName = superName == null ? 0 : newClass(superName);
508         if (interfaces != null && interfaces.length > 0) {
509             interfaceCount = interfaces.length;
510             this.interfaces = new int[interfaceCount];
511             for (int i = 0; i < interfaceCount; ++i) {
512                 this.interfaces[i] = newClass(interfaces[i]);
513             }
514         }
515     }
516
517     public void visitSource(final String file, final String debug) {
518         if (file != null) {
519             sourceFile = newUTF8(file);
520         }
521         if (debug != null) {
522             sourceDebug = new ByteVector();
523             sourceDebug.putUTF8(debug);
524         }
525     }
526
527     public void visitOuterClass(
528         final String owner,
529         final String name,
530         final String desc)
531     {
532         enclosingMethodOwner = newClass(owner);
533         if (name != null && desc != null) {
534             enclosingMethod = newNameType(name, desc);
535         }
536     }
537
538     public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
539         ByteVector bv = new ByteVector();
540         // write type, and reserve space for values count
541 bv.putShort(newUTF8(desc)).putShort(0);
542         AnnotationWriter aw = new AnnotationWriter(this, true, bv, bv, 2);
543         if (visible) {
544             aw.next = anns;
545             anns = aw;
546         } else {
547             aw.next = ianns;
548             ianns = aw;
549         }
550         return aw;
551     }
552
553     public void visitAttribute(final Attribute attr) {
554         attr.next = attrs;
555         attrs = attr;
556     }
557
558     public void visitInnerClass(
559         final String name,
560         final String outerName,
561         final String innerName,
562         final int access)
563     {
564         if (innerClasses == null) {
565             innerClasses = new ByteVector();
566         }
567         ++innerClassesCount;
568         innerClasses.putShort(name == null ? 0 : newClass(name));
569         innerClasses.putShort(outerName == null ? 0 : newClass(outerName));
570         innerClasses.putShort(innerName == null ? 0 : newUTF8(innerName));
571         innerClasses.putShort(access);
572     }
573
574     public FieldVisitor visitField(
575         final int access,
576         final String name,
577         final String desc,
578         final String signature,
579         final Object value)
580     {
581         return new FieldWriter(this, access, name, desc, signature, value);
582     }
583
584     public MethodVisitor visitMethod(
585         final int access,
586         final String name,
587         final String desc,
588         final String signature,
589         final String [] exceptions)
590     {
591         return new MethodWriter(this,
592                 access,
593                 name,
594                 desc,
595                 signature,
596                 exceptions,
597                 computeMaxs);
598     }
599
600     public void visitEnd() {
601     }
602
603     // ------------------------------------------------------------------------
604 // Other public methods
605 // ------------------------------------------------------------------------
606
607     /**
608      * Returns the bytecode of the class that was build with this class writer.
609      *
610      * @return the bytecode of the class that was build with this class writer.
611      */
612     public byte[] toByteArray() {
613         // computes the real size of the bytecode of this class
614 int size = 24 + 2 * interfaceCount;
615         int nbFields = 0;
616         FieldWriter fb = firstField;
617         while (fb != null) {
618             ++nbFields;
619             size += fb.getSize();
620             fb = fb.next;
621         }
622         int nbMethods = 0;
623         MethodWriter mb = firstMethod;
624         while (mb != null) {
625             ++nbMethods;
626             size += mb.getSize();
627             mb = mb.next;
628         }
629         int attributeCount = 0;
630         if (signature != 0) {
631             ++attributeCount;
632             size += 8;
633             newUTF8("Signature");
634         }
635         if (sourceFile != 0) {
636             ++attributeCount;
637             size += 8;
638             newUTF8("SourceFile");
639         }
640         if (sourceDebug != null) {
641             ++attributeCount;
642             size += sourceDebug.length;
643             newUTF8("SourceDebugExtension");
644         }
645         if (enclosingMethodOwner != 0) {
646             ++attributeCount;
647             size += 10;
648             newUTF8("EnclosingMethod");
649         }
650         if ((access & Opcodes.ACC_DEPRECATED) != 0) {
651             ++attributeCount;
652             size += 6;
653             newUTF8("Deprecated");
654         }
655         if ((access & Opcodes.ACC_SYNTHETIC) != 0
656                 && (version & 0xffff) < Opcodes.V1_5)
657         {
658             ++attributeCount;
659             size += 6;
660             newUTF8("Synthetic");
661         }
662         if (version == Opcodes.V1_4) {
663             if ((access & Opcodes.ACC_ANNOTATION) != 0) {
664                 ++attributeCount;
665                 size += 6;
666                 newUTF8("Annotation");
667             }
668             if ((access & Opcodes.ACC_ENUM) != 0) {
669                 ++attributeCount;
670                 size += 6;
671                 newUTF8("Enum");
672             }
673         }
674         if (innerClasses != null) {
675             ++attributeCount;
676             size += 8 + innerClasses.length;
677             newUTF8("InnerClasses");
678         }
679         if (anns != null) {
680             ++attributeCount;
681             size += 8 + anns.getSize();
682             newUTF8("RuntimeVisibleAnnotations");
683         }
684         if (ianns != null) {
685             ++attributeCount;
686             size += 8 + ianns.getSize();
687             newUTF8("RuntimeInvisibleAnnotations");
688         }
689         if (attrs != null) {
690             attributeCount += attrs.getCount();
691             size += attrs.getSize(this, null, 0, -1, -1);
692         }
693         size += pool.length;
694         // allocates a byte vector of this size, in order to avoid unnecessary
695 // arraycopy operations in the ByteVector.enlarge() method
696 ByteVector out = new ByteVector(size);
697         out.putInt(0xCAFEBABE).putInt(version);
698         out.putShort(index).putByteArray(pool.data, 0, pool.length);
699         out.putShort(access).putShort(name).putShort(superName);
700         out.putShort(interfaceCount);
701         for (int i = 0; i < interfaceCount; ++i) {
702             out.putShort(interfaces[i]);
703         }
704         out.putShort(nbFields);
705         fb = firstField;
706         while (fb != null) {
707             fb.put(out);
708             fb = fb.next;
709         }
710         out.putShort(nbMethods);
711         mb = firstMethod;
712         while (mb != null) {
713             mb.put(out);
714             mb = mb.next;
715         }
716         out.putShort(attributeCount);
717         if (signature != 0) {
718             out.putShort(newUTF8("Signature")).putInt(2).putShort(signature);
719         }
720         if (sourceFile != 0) {
721             out.putShort(newUTF8("SourceFile")).putInt(2).putShort(sourceFile);
722         }
723         if (sourceDebug != null) {
724             int len = sourceDebug.length;
725             out.putShort(newUTF8("SourceDebugExtension")).putInt(len);
726             out.putByteArray(sourceDebug.data, 0, len);
727         }
728         if (enclosingMethodOwner != 0) {
729             out.putShort(newUTF8("EnclosingMethod")).putInt(4);
730             out.putShort(enclosingMethodOwner).putShort(enclosingMethod);
731         }
732         if ((access & Opcodes.ACC_DEPRECATED) != 0) {
733             out.putShort(newUTF8("Deprecated")).putInt(0);
734         }
735         if ((access & Opcodes.ACC_SYNTHETIC) != 0
736                 && (version & 0xffff) < Opcodes.V1_5)
737         {
738             out.putShort(newUTF8("Synthetic")).putInt(0);
739         }
740         if (version == Opcodes.V1_4) {
741             if ((access & Opcodes.ACC_ANNOTATION) != 0) {
742                 out.putShort(newUTF8("Annotation")).putInt(0);
743             }
744             if ((access & Opcodes.ACC_ENUM) != 0) {
745                 out.putShort(newUTF8("Enum")).putInt(0);
746             }
747         }
748         if (innerClasses != null) {
749             out.putShort(newUTF8("InnerClasses"));
750             out.putInt(innerClasses.length + 2).putShort(innerClassesCount);
751             out.putByteArray(innerClasses.data, 0, innerClasses.length);
752         }
753         if (anns != null) {
754             out.putShort(newUTF8("RuntimeVisibleAnnotations"));
755             anns.put(out);
756         }
757         if (ianns != null) {
758             out.putShort(newUTF8("RuntimeInvisibleAnnotations"));
759             ianns.put(out);
760         }
761         if (attrs != null) {
762             attrs.put(this, null, 0, -1, -1, out);
763         }
764         return out.data;
765     }
766
767     // ------------------------------------------------------------------------
768 // Utility methods: constant pool management
769 // ------------------------------------------------------------------------
770
771     /**
772      * Adds a number or string constant to the constant pool of the class being
773      * build. Does nothing if the constant pool already contains a similar item.
774      *
775      * @param cst the value of the constant to be added to the constant pool.
776      * This parameter must be an {@link Integer}, a {@link Float}, a
777      * {@link Long}, a {@link Double}, a {@link String} or a
778      * {@link Type}.
779      * @return a new or already existing constant item with the given value.
780      */
781     Item newConstItem(final Object cst) {
782         if (cst instanceof Integer ) {
783             int val = ((Integer ) cst).intValue();
784             return newInteger(val);
785         } else if (cst instanceof Byte ) {
786             int val = ((Byte ) cst).intValue();
787             return newInteger(val);
788         } else if (cst instanceof Character ) {
789             int val = ((Character ) cst).charValue();
790             return newInteger(val);
791         } else if (cst instanceof Short ) {
792             int val = ((Short ) cst).intValue();
793             return newInteger(val);
794         } else if (cst instanceof Boolean ) {
795             int val = ((Boolean ) cst).booleanValue() ? 1 : 0;
796             return newInteger(val);
797         } else if (cst instanceof Float ) {
798             float val = ((Float ) cst).floatValue();
799             return newFloat(val);
800         } else if (cst instanceof Long ) {
801             long val = ((Long ) cst).longValue();
802             return newLong(val);
803         } else if (cst instanceof Double ) {
804             double val = ((Double ) cst).doubleValue();
805             return newDouble(val);
806         } else if (cst instanceof String ) {
807             return newString((String ) cst);
808         } else if (cst instanceof Type) {
809             Type t = (Type) cst;
810             return newClassItem(t.getSort() == Type.OBJECT
811                     ? t.getInternalName()
812                     : t.getDescriptor());
813         } else {
814             throw new IllegalArgumentException ("value " + cst);
815         }
816     }
817
818     /**
819      * Adds a number or string constant to the constant pool of the class being
820      * build. Does nothing if the constant pool already contains a similar item.
821      * <i>This method is intended for {@link Attribute} sub classes, and is
822      * normally not needed by class generators or adapters.</i>
823      *
824      * @param cst the value of the constant to be added to the constant pool.
825      * This parameter must be an {@link Integer}, a {@link Float}, a
826      * {@link Long}, a {@link Double} or a {@link String}.
827      * @return the index of a new or already existing constant item with the
828      * given value.
829      */
830     public int newConst(final Object cst) {
831         return newConstItem(cst).index;
832     }
833
834     /**
835      * Adds an UTF8 string to the constant pool of the class being build. Does
836      * nothing if the constant pool already contains a similar item. <i>This
837      * method is intended for {@link Attribute} sub classes, and is normally not
838      * needed by class generators or adapters.</i>
839      *
840      * @param value the String value.
841      * @return the index of a new or already existing UTF8 item.
842      */
843     public int newUTF8(final String value) {
844         key.set('s', value, null, null);
845         Item result = get(key);
846         if (result == null) {
847             pool.putByte(UTF8).putUTF8(value);
848             result = new Item(index++, key);
849             put(result);
850         }
851         return result.index;
852     }
853
854     /**
855      * Adds a class reference to the constant pool of the class being build.
856      * Does nothing if the constant pool already contains a similar item.
857      * <i>This method is intended for {@link Attribute} sub classes, and is
858      * normally not needed by class generators or adapters.</i>
859      *
860      * @param value the internal name of the class.
861      * @return the index of a new or already existing class reference item.
862      */
863     public int newClass(final String value) {
864         return newClassItem(value).index;
865     }
866
867     /**
868      * Adds a class reference to the constant pool of the class being build.
869      * Does nothing if the constant pool already contains a similar item.
870      * <i>This method is intended for {@link Attribute} sub classes, and is
871      * normally not needed by class generators or adapters.</i>
872      *
873      * @param value the internal name of the class.
874      * @return a new or already existing class reference item.
875      */
876     private Item newClassItem(final String value) {
877         key2.set('C', value, null, null);
878         Item result = get(key2);
879         if (result == null) {
880             pool.put12(CLASS, newUTF8(value));
881             result = new Item(index++, key2);
882             put(result);
883         }
884         return result;
885     }
886
887     /**
888      * Adds a field reference to the constant pool of the class being build.
889      * Does nothing if the constant pool already contains a similar item.
890      * <i>This method is intended for {@link Attribute} sub classes, and is
891      * normally not needed by class generators or adapters.</i>
892      *
893      * @param owner the internal name of the field's owner class.
894      * @param name the field's name.
895      * @param desc the field's descriptor.
896      * @return the index of a new or already existing field reference item.
897      */
898     public int newField(final String owner, final String name, final String desc)
899     {
900         key3.set('G', owner, name, desc);
901         Item result = get(key3);
902         if (result == null) {
903             put122(FIELD, newClass(owner), newNameType(name, desc));
904             result = new Item(index++, key3);
905             put(result);
906         }
907         return result.index;
908     }
909
910     /**
911      * Adds a method reference to the constant pool of the class being build.
912      * Does nothing if the constant pool already contains a similar item.
913      *
914      * @param owner the internal name of the method's owner class.
915      * @param name the method's name.
916      * @param desc the method's descriptor.
917      * @param itf <tt>true</tt> if <tt>owner</tt> is an interface.
918      * @return a new or already existing method reference item.
919      */
920     Item newMethodItem(
921         final String owner,
922         final String name,
923         final String desc,
924         final boolean itf)
925     {
926         key3.set(itf ? 'N' : 'M', owner, name, desc);
927         Item result = get(key3);
928         if (result == null) {
929             put122(itf ? IMETH : METH, newClass(owner), newNameType(name, desc));
930             result = new Item(index++, key3);
931             put(result);
932         }
933         return result;
934     }
935
936     /**
937      * Adds a method reference to the constant pool of the class being build.
938      * Does nothing if the constant pool already contains a similar item.
939      * <i>This method is intended for {@link Attribute} sub classes, and is
940      * normally not needed by class generators or adapters.</i>
941      *
942      * @param owner the internal name of the method's owner class.
943      * @param name the method's name.
944      * @param desc the method's descriptor.
945      * @param itf <tt>true</tt> if <tt>owner</tt> is an interface.
946      * @return the index of a new or already existing method reference item.
947      */
948     public int newMethod(
949         final String owner,
950         final String name,
951         final String desc,
952         final boolean itf)
953     {
954         return newMethodItem(owner, name, desc, itf).index;
955     }
956
957     /**
958      * Adds an integer to the constant pool of the class being build. Does
959      * nothing if the constant pool already contains a similar item.
960      *
961      * @param value the int value.
962      * @return a new or already existing int item.
963      */
964     Item newInteger(final int value) {
965         key.set(value);
966         Item result = get(key);
967         if (result == null) {
968             pool.putByte(INT).putInt(value);
969             result = new Item(index++, key);
970             put(result);
971         }
972         return result;
973     }
974
975     /**
976      * Adds a float to the constant pool of the class being build. Does nothing
977      * if the constant pool already contains a similar item.
978      *
979      * @param value the float value.
980      * @return a new or already existing float item.
981      */
982     Item newFloat(final float value) {
983         key.set(value);
984         Item result = get(key);
985         if (result == null) {
986             pool.putByte(FLOAT).putInt(Float.floatToIntBits(value));
987             result = new Item(index++, key);
988             put(result);
989         }
990         return result;
991     }
992
993     /**
994      * Adds a long to the constant pool of the class being build. Does nothing
995      * if the constant pool already contains a similar item.
996      *
997      * @param value the long value.
998      * @return a new or already existing long item.
999      */
1000    Item newLong(final long value) {
1001        key.set(value);
1002        Item result = get(key);
1003        if (result == null) {
1004            pool.putByte(LONG).putLong(value);
1005            result = new Item(index, key);
1006            put(result);
1007            index += 2;
1008        }
1009        return result;
1010    }
1011
1012    /**
1013     * Adds a double to the constant pool of the class being build. Does nothing
1014     * if the constant pool already contains a similar item.
1015     *
1016     * @param value the double value.
1017     * @return a new or already existing double item.
1018     */
1019    Item newDouble(final double value) {
1020        key.set(value);
1021        Item result = get(key);
1022        if (result == null) {
1023            pool.putByte(DOUBLE).putLong(Double.doubleToLongBits(value));
1024            result = new Item(index, key);
1025            put(result);
1026            index += 2;
1027        }
1028        return result;
1029    }
1030
1031    /**
1032     * Adds a string to the constant pool of the class being build. Does nothing
1033     * if the constant pool already contains a similar item.
1034     *
1035     * @param value the String value.
1036     * @return a new or already existing string item.
1037     */
1038    private Item newString(final String value) {
1039        key2.set('S', value, null, null);
1040        Item result = get(key2);
1041        if (result == null) {
1042            pool.put12(STR, newUTF8(value));
1043            result = new Item(index++, key2);
1044            put(result);
1045        }
1046        return result;
1047    }
1048
1049    /**
1050     * Adds a name and type to the constant pool of the class being build. Does
1051     * nothing if the constant pool already contains a similar item. <i>This
1052     * method is intended for {@link Attribute} sub classes, and is normally not
1053     * needed by class generators or adapters.</i>
1054     *
1055     * @param name a name.
1056     * @param desc a type descriptor.
1057     * @return the index of a new or already existing name and type item.
1058     */
1059    public int newNameType(final String name, final String desc) {
1060        key2.set('T', name, desc, null);
1061        Item result = get(key2);
1062        if (result == null) {
1063            put122(NAME_TYPE, newUTF8(name), newUTF8(desc));
1064            result = new Item(index++, key2);
1065            put(result);
1066        }
1067        return result.index;
1068    }
1069
1070    /**
1071     * Returns the constant pool's hash table item which is equal to the given
1072     * item.
1073     *
1074     * @param key a constant pool item.
1075     * @return the constant pool's hash table item which is equal to the given
1076     * item, or <tt>null</tt> if there is no such item.
1077     */
1078    private Item get(final Item key) {
1079        int h = key.hashCode;
1080        Item i = items[h % items.length];
1081        while (i != null) {
1082            if (i.hashCode == h && key.isEqualTo(i)) {
1083                return i;
1084            }
1085            i = i.next;
1086        }
1087        return null;
1088    }
1089
1090    /**
1091     * Puts the given item in the constant pool's hash table. The hash table
1092     * <i>must</i> not already contains this item.
1093     *
1094     * @param i the item to be added to the constant pool's hash table.
1095     */
1096    private void put(final Item i) {
1097        if (index > threshold) {
1098            Item[] newItems = new Item[items.length * 2 + 1];
1099            for (int l = items.length - 1; l >= 0; --l) {
1100                Item j = items[l];
1101                while (j != null) {
1102                    int index = j.hashCode % newItems.length;
1103                    Item k = j.next;
1104                    j.next = newItems[index];
1105                    newItems[index] = j;
1106                    j = k;
1107                }
1108            }
1109            items = newItems;
1110            threshold = (int) (items.length * 0.75);
1111        }
1112        int index = i.hashCode % items.length;
1113        i.next = items[index];
1114        items[index] = i;
1115    }
1116
1117    /**
1118     * Puts one byte and two shorts into the constant pool.
1119     *
1120     * @param b a byte.
1121     * @param s1 a short.
1122     * @param s2 another short.
1123     */
1124    private void put122(final int b, final int s1, final int s2) {
1125        pool.put12(b, s1).putShort(s2);
1126    }
1127}
1128

A to Z: JavaDoc & Examples

---

Daily Java News & Articles

---

Open Source Projects

---

Open Source Codes

---

Free Computer Books

---

Remove Frame

---

Free Books   Free Magazines  

Popular Tags