Sort


1   /*
2    * Copyright 2001-2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  /*
17   * $Id: Sort.java,v 1.23 2004/02/24 02:58:42 zongaro Exp $
18   */
19  
20  package org.apache.xalan.xsltc.compiler;
21  
22  import java.text.Collator  ;
23  import java.util.ArrayList  ;
24  import java.util.NoSuchElementException  ;
25  import java.util.StringTokenizer  ;
26  import java.util.Vector  ;
27  
28  import org.apache.bcel.classfile.Field;
29  import org.apache.bcel.classfile.Method;
30  import org.apache.bcel.generic.ALOAD;
31  import org.apache.bcel.generic.ANEWARRAY;
32  import org.apache.bcel.generic.CHECKCAST;
33  import org.apache.bcel.generic.ConstantPoolGen;
34  import org.apache.bcel.generic.GETFIELD;
35  import org.apache.bcel.generic.ICONST;
36  import org.apache.bcel.generic.ILOAD;
37  import org.apache.bcel.generic.INVOKEINTERFACE;
38  import org.apache.bcel.generic.INVOKESPECIAL;
39  import org.apache.bcel.generic.INVOKESTATIC;
40  import org.apache.bcel.generic.INVOKEVIRTUAL;
41  import org.apache.bcel.generic.InstructionHandle;
42  import org.apache.bcel.generic.InstructionList;
43  import org.apache.bcel.generic.NEW;
44  import org.apache.bcel.generic.NOP;
45  import org.apache.bcel.generic.PUSH;
46  import org.apache.bcel.generic.PUTFIELD;
47  import org.apache.bcel.generic.TABLESWITCH;
48  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
49  import org.apache.xalan.xsltc.compiler.util.CompareGenerator;
50  import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
51  import org.apache.xalan.xsltc.compiler.util.IntType;
52  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
53  import org.apache.xalan.xsltc.compiler.util.NodeSortRecordFactGenerator;
54  import org.apache.xalan.xsltc.compiler.util.NodeSortRecordGenerator;
55  import org.apache.xalan.xsltc.compiler.util.StringType;
56  import org.apache.xalan.xsltc.compiler.util.Type;
57  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
58  import org.apache.xalan.xsltc.compiler.util.Util;
59  import org.apache.xalan.xsltc.dom.Axis;
60  
61  
62  /**
63   * @author Jacek Ambroziak
64   * @author Santiago Pericas-Geertsen
65   * @author Morten Jorgensen
66   */
67  final class Sort extends Instruction implements Closure {
68  
69      private Expression     _select;
70      private AttributeValue _order;
71      private AttributeValue _caseOrder;
72      private AttributeValue _dataType;
73      private String    _lang; // bug! see 26869
74  
75      private String           _data = null;
76  
77  
78      private String   _className = null;
79      private ArrayList   _closureVars = null;
80      private boolean _needsSortRecordFactory = false;
81  
82      // -- Begin Closure interface --------------------
83  
84      /**
85       * Returns true if this closure is compiled in an inner class (i.e.
86       * if this is a real closure).
87       */
88      public boolean inInnerClass() {
89      return (_className != null);
90      }
91  
92      /**
93       * Returns a reference to its parent closure or null if outermost.
94       */
95      public Closure getParentClosure() {
96      return null;
97      }
98  
99      /**
100      * Returns the name of the auxiliary class or null if this predicate 
101      * is compiled inside the Translet.
102      */
103     public String   getInnerClassName() {
104     return _className;
105     }
106 
107     /**
108      * Add new variable to the closure.
109      */
110     public void addVariable(VariableRefBase variableRef) {
111     if (_closureVars == null) {
112         _closureVars = new ArrayList  ();
113     }
114 
115     // Only one reference per variable
116     if (!_closureVars.contains(variableRef)) {
117         _closureVars.add(variableRef);
118         _needsSortRecordFactory = true;
119     }
120     }
121 
122     // -- End Closure interface ----------------------
123 
124     private void setInnerClassName(String   className) {
125     _className = className;
126     }
127 
128     /**
129      * Parse the attributes of the xsl:sort element
130      */
131     public void parseContents(Parser parser) {
132 
133     final SyntaxTreeNode parent = getParent();
134     if (!(parent instanceof ApplyTemplates) &&
135         !(parent instanceof ForEach)) {
136         reportError(this, parser, ErrorMsg.STRAY_SORT_ERR, null);
137         return;
138     }
139 
140     // Parse the select expression (node string value if no expression)
141     _select = parser.parseExpression(this, "select", "string(.)");
142 
143     // Get the sort order; default is 'ascending'
144     String   val = getAttribute("order");
145     if (val.length() == 0) val = "ascending";
146     _order = AttributeValue.create(this, val, parser);
147 
148     // Get the sort data type; default is text
149     val = getAttribute("data-type");
150     if (val.length() == 0) {
151         try {
152         final Type type = _select.typeCheck(parser.getSymbolTable());
153         if (type instanceof IntType)
154             val = "number";
155         else
156             val = "text";
157         }
158         catch (TypeCheckError e) {
159         val = "text";
160         }
161     }
162     _dataType = AttributeValue.create(this, val, parser);
163 
164      _lang =  getAttribute("lang"); // bug! see 26869
165   // val =  getAttribute("lang"); 
166   // _lang = AttributeValue.create(this, val, parser);
167         // Get the case order; default is language dependant
168     val = getAttribute("case-order");
169     _caseOrder = AttributeValue.create(this, val, parser);
170     
171     }
172     
173     /**
174      * Run type checks on the attributes; expression must return a string
175      * which we will use as a sort key
176      */
177     public Type typeCheck(SymbolTable stable) throws TypeCheckError {
178     final Type tselect = _select.typeCheck(stable);
179 
180     // If the sort data-type is not set we use the natural data-type
181     // of the data we will sort
182     if (!(tselect instanceof StringType)) {
183         _select = new CastExpr(_select, Type.String);
184     }
185 
186     _order.typeCheck(stable);
187     _caseOrder.typeCheck(stable);
188     _dataType.typeCheck(stable);
189     return Type.Void;
190     }
191 
192     /**
193      * These two methods are needed in the static methods that compile the
194      * overloaded NodeSortRecord.compareType() and NodeSortRecord.sortOrder()
195      */
196     public void translateSortType(ClassGenerator classGen,
197                   MethodGenerator methodGen) {
198     _dataType.translate(classGen, methodGen);
199     }
200     
201     public void translateSortOrder(ClassGenerator classGen,
202                    MethodGenerator methodGen) {
203     _order.translate(classGen, methodGen);
204     }
205     
206      public void translateCaseOrder(ClassGenerator classGen,
207                    MethodGenerator methodGen) {
208     _caseOrder.translate(classGen, methodGen);
209     }
210     
211     public void translateLang(ClassGenerator classGen,
212                    MethodGenerator methodGen) {
213     final ConstantPoolGen cpg = classGen.getConstantPool();
214     final InstructionList il = methodGen.getInstructionList();
215     il.append(new PUSH(cpg, _lang)); // bug! see 26869
216     }
217     
218     /**
219      * This method compiles code for the select expression for this
220      * xsl:sort element. The method is called from the static code-generating
221      * methods in this class.
222      */
223     public void translateSelect(ClassGenerator classGen,
224                 MethodGenerator methodGen) {
225     _select.translate(classGen,methodGen);
226     }
227 
228     /**
229      * This method should not produce any code
230      */
231     public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
232     // empty
233     }
234 
235     /**
236      * Compiles code that instantiates a SortingIterator object.
237      * This object's constructor needs referencdes to the current iterator
238      * and a node sort record producing objects as its parameters.
239      */
240     public static void translateSortIterator(ClassGenerator classGen,
241                       MethodGenerator methodGen,
242                       Expression nodeSet,
243                       Vector   sortObjects) 
244     {
245     final ConstantPoolGen cpg = classGen.getConstantPool();
246     final InstructionList il = methodGen.getInstructionList();
247 
248     // SortingIterator.SortingIterator(NodeIterator,NodeSortRecordFactory);
249     final int init = cpg.addMethodref(SORT_ITERATOR, "<init>",
250                       "("
251                       + NODE_ITERATOR_SIG
252                       + NODE_SORT_FACTORY_SIG
253                       + ")V");  
254 
255     il.append(new NEW(cpg.addClass(SORT_ITERATOR)));
256     il.append(DUP);
257 
258     // Get the current node iterator
259     if (nodeSet == null) {  // apply-templates default
260         final int children = cpg.addInterfaceMethodref(DOM_INTF,
261                                "getAxisIterator",
262                                "(I)"+
263                                NODE_ITERATOR_SIG);
264         il.append(methodGen.loadDOM());
265         il.append(new PUSH(cpg, Axis.CHILD));
266         il.append(new INVOKEINTERFACE(children, 2));
267     }
268     else {
269         nodeSet.translate(classGen, methodGen);
270     }
271     
272     // Compile the code for the NodeSortRecord producing class and pass
273     // that as the last argument to the SortingIterator constructor.
274     compileSortRecordFactory(sortObjects, classGen, methodGen);
275     il.append(new INVOKESPECIAL(init));
276     }
277 
278 
279     /**
280      * Compiles code that instantiates a NodeSortRecordFactory object which
281      * will produce NodeSortRecord objects of a specific type.
282      */
283     public static void compileSortRecordFactory(Vector   sortObjects,
284     ClassGenerator classGen, MethodGenerator methodGen) 
285     {
286     String   sortRecordClass = 
287         compileSortRecord(sortObjects, classGen, methodGen);
288 
289     boolean needsSortRecordFactory = false;
290     final int nsorts = sortObjects.size();
291     for (int i = 0; i < nsorts; i++) {
292         final Sort sort = (Sort) sortObjects.elementAt(i);
293         needsSortRecordFactory |= sort._needsSortRecordFactory;
294     }
295 
296     String   sortRecordFactoryClass = NODE_SORT_FACTORY;
297     if (needsSortRecordFactory) {
298         sortRecordFactoryClass = 
299         compileSortRecordFactory(sortObjects, classGen, methodGen, 
300             sortRecordClass);
301     }
302 
303     final ConstantPoolGen cpg = classGen.getConstantPool();
304     final InstructionList il = methodGen.getInstructionList();
305     
306     il.append(new NEW(cpg.addClass(sortRecordFactoryClass)));
307     il.append(DUP);
308     il.append(methodGen.loadDOM());
309     il.append(new PUSH(cpg, sortRecordClass));
310     il.append(classGen.loadTranslet());
311 
312     // Compile code that initializes the static _sortOrder
313     il.append(new PUSH(cpg, nsorts));
314     il.append(new ANEWARRAY(cpg.addClass(STRING)));
315     for (int level = 0; level < nsorts; level++) {
316         final Sort sort = (Sort)sortObjects.elementAt(level);
317         il.append(DUP);
318         il.append(new PUSH(cpg, level));
319         sort.translateSortOrder(classGen, methodGen);
320         il.append(AASTORE);
321     }
322 
323     il.append(new PUSH(cpg, nsorts));
324     il.append(new ANEWARRAY(cpg.addClass(STRING)));
325     for (int level = 0; level < nsorts; level++) {
326         final Sort sort = (Sort)sortObjects.elementAt(level);
327         il.append(DUP);
328         il.append(new PUSH(cpg, level));
329         sort.translateSortType(classGen, methodGen);
330         il.append(AASTORE);
331     }
332   
333   il.append(new PUSH(cpg, nsorts));
334   il.append(new ANEWARRAY(cpg.addClass(STRING)));
335   for (int level = 0; level < nsorts; level++) {
336         final Sort sort = (Sort)sortObjects.elementAt(level);
337         il.append(DUP);
338         il.append(new PUSH(cpg, level));
339         sort.translateLang(classGen, methodGen);
340         il.append(AASTORE);
341    }
342  
343    il.append(new PUSH(cpg, nsorts));
344    il.append(new ANEWARRAY(cpg.addClass(STRING)));
345    for (int level = 0; level < nsorts; level++) {
346         final Sort sort = (Sort)sortObjects.elementAt(level);
347         il.append(DUP);
348         il.append(new PUSH(cpg, level));
349         sort.translateCaseOrder(classGen, methodGen);
350         il.append(AASTORE);
351   }
352 
353     il.append(new INVOKESPECIAL(
354         cpg.addMethodref(sortRecordFactoryClass, "<init>", 
355         "(" + DOM_INTF_SIG 
356             + STRING_SIG
357             + TRANSLET_INTF_SIG
358             + "[" + STRING_SIG
359         + "[" + STRING_SIG
360         + "[" + STRING_SIG
361             + "[" + STRING_SIG + ")V")));
362 
363     // Initialize closure variables in sortRecordFactory
364     final ArrayList   dups = new ArrayList  ();
365 
366     for (int j = 0; j < nsorts; j++) {
367         final Sort sort = (Sort) sortObjects.get(j);
368         final int length = (sort._closureVars == null) ? 0 : 
369         sort._closureVars.size();
370 
371         for (int i = 0; i < length; i++) {
372         VariableRefBase varRef = (VariableRefBase) sort._closureVars.get(i);
373 
374         // Discard duplicate variable references
375         if (dups.contains(varRef)) continue;
376 
377         final VariableBase var = varRef.getVariable();
378 
379         // Store variable in new closure
380         il.append(DUP);
381         il.append(var.loadInstruction());
382         il.append(new PUTFIELD(
383             cpg.addFieldref(sortRecordFactoryClass, var.getEscapedName(), 
384                 var.getType().toSignature())));
385         dups.add(varRef);
386         }
387     }
388     }
389 
390     public static String   compileSortRecordFactory(Vector   sortObjects,
391     ClassGenerator classGen, MethodGenerator methodGen, 
392     String   sortRecordClass)
393     {
394     final XSLTC  xsltc = ((Sort)sortObjects.firstElement()).getXSLTC();
395     final String   className = xsltc.getHelperClassName();
396 
397     final NodeSortRecordFactGenerator sortRecordFactory =
398         new NodeSortRecordFactGenerator(className,
399                     NODE_SORT_FACTORY,
400                     className + ".java",
401                     ACC_PUBLIC | ACC_SUPER | ACC_FINAL,
402                     new String  [] {},
403                     classGen.getStylesheet());
404 
405     ConstantPoolGen cpg = sortRecordFactory.getConstantPool();
406 
407     // Add a new instance variable for each var in closure
408     final int nsorts = sortObjects.size();
409     final ArrayList   dups = new ArrayList  ();
410 
411     for (int j = 0; j < nsorts; j++) {
412         final Sort sort = (Sort) sortObjects.get(j);
413         final int length = (sort._closureVars == null) ? 0 : 
414         sort._closureVars.size();
415 
416         for (int i = 0; i < length; i++) {
417         final VariableRefBase varRef = (VariableRefBase) sort._closureVars.get(i);
418 
419         // Discard duplicate variable references
420         if (dups.contains(varRef)) continue;
421 
422         final VariableBase var = varRef.getVariable();
423         sortRecordFactory.addField(new Field(ACC_PUBLIC, 
424                        cpg.addUtf8(var.getEscapedName()),
425                        cpg.addUtf8(var.getType().toSignature()),
426                        null, cpg.getConstantPool()));
427         dups.add(varRef);
428         }
429     }
430 
431     // Define a constructor for this class
432     final org.apache.bcel.generic.Type[] argTypes = 
433         new org.apache.bcel.generic.Type[7];
434     argTypes[0] = Util.getJCRefType(DOM_INTF_SIG);
435     argTypes[1] = Util.getJCRefType(STRING_SIG);
436     argTypes[2] = Util.getJCRefType(TRANSLET_INTF_SIG);
437     argTypes[3] = Util.getJCRefType("[" + STRING_SIG);
438     argTypes[4] = Util.getJCRefType("[" + STRING_SIG);
439   argTypes[5] = Util.getJCRefType("[" + STRING_SIG);
440   argTypes[6] = Util.getJCRefType("[" + STRING_SIG);
441 
442     final String  [] argNames = new String  [7];
443     argNames[0] = DOCUMENT_PNAME;
444     argNames[1] = "className";
445     argNames[2] = TRANSLET_PNAME;
446     argNames[3] = "order";
447     argNames[4] = "type";
448   argNames[5] = "lang";
449   argNames[6] = "case_order";
450   
451 
452     InstructionList il = new InstructionList();
453     final MethodGenerator constructor =
454         new MethodGenerator(ACC_PUBLIC,
455                 org.apache.bcel.generic.Type.VOID, 
456                 argTypes, argNames, "<init>", 
457                 className, il, cpg);
458 
459     // Push all parameters onto the stack and called super.<init>()
460     il.append(ALOAD_0);
461     il.append(ALOAD_1);
462     il.append(ALOAD_2);
463     il.append(new ALOAD(3));
464     il.append(new ALOAD(4));
465     il.append(new ALOAD(5));
466   il.append(new ALOAD(6));
467   il.append(new ALOAD(7));
468     il.append(new INVOKESPECIAL(cpg.addMethodref(NODE_SORT_FACTORY,
469         "<init>", 
470         "(" + DOM_INTF_SIG 
471         + STRING_SIG 
472         + TRANSLET_INTF_SIG 
473         + "[" + STRING_SIG
474     + "[" + STRING_SIG
475     + "[" + STRING_SIG
476         + "[" + STRING_SIG + ")V")));
477     il.append(RETURN);
478 
479     // Override the definition of makeNodeSortRecord()
480     il = new InstructionList(); 
481     final MethodGenerator makeNodeSortRecord =
482         new MethodGenerator(ACC_PUBLIC,
483         Util.getJCRefType(NODE_SORT_RECORD_SIG), 
484         new org.apache.bcel.generic.Type[] { 
485             org.apache.bcel.generic.Type.INT,
486             org.apache.bcel.generic.Type.INT },
487         new String  [] { "node", "last" }, "makeNodeSortRecord",
488         className, il, cpg);
489 
490     il.append(ALOAD_0);
491     il.append(ILOAD_1);
492     il.append(ILOAD_2);
493     il.append(new INVOKESPECIAL(cpg.addMethodref(NODE_SORT_FACTORY,
494         "makeNodeSortRecord", "(II)" + NODE_SORT_RECORD_SIG)));
495     il.append(DUP);
496     il.append(new CHECKCAST(cpg.addClass(sortRecordClass)));
497 
498     // Initialize closure in record class
499     final int ndups = dups.size();
500     for (int i = 0; i < ndups; i++) {
501         final VariableRefBase varRef = (VariableRefBase) dups.get(i);
502         final VariableBase var = varRef.getVariable();
503         final Type varType = var.getType();
504         
505         il.append(DUP);
506 
507         // Get field from factory class
508         il.append(ALOAD_0);
509         il.append(new GETFIELD(
510         cpg.addFieldref(className,
511             var.getEscapedName(), varType.toSignature())));
512 
513         // Put field in record class
514         il.append(new PUTFIELD(
515         cpg.addFieldref(sortRecordClass,
516             var.getEscapedName(), varType.toSignature())));
517     }
518     il.append(POP);
519     il.append(ARETURN);
520 
521     constructor.setMaxLocals();
522     constructor.setMaxStack();
523     sortRecordFactory.addMethod(constructor.getMethod());
524     makeNodeSortRecord.setMaxLocals();
525     makeNodeSortRecord.setMaxStack();
526     sortRecordFactory.addMethod(makeNodeSortRecord.getMethod());
527     xsltc.dumpClass(sortRecordFactory.getJavaClass());
528 
529     return className;
530     }
531 
532     /**
533      * Create a new auxillary class extending NodeSortRecord.
534      */
535     private static String   compileSortRecord(Vector   sortObjects,
536                         ClassGenerator classGen,
537                         MethodGenerator methodGen) {
538     final XSLTC  xsltc = ((Sort)sortObjects.firstElement()).getXSLTC();
539     final String   className = xsltc.getHelperClassName();
540 
541     // This generates a new class for handling this specific sort
542     final NodeSortRecordGenerator sortRecord =
543         new NodeSortRecordGenerator(className,
544                     NODE_SORT_RECORD,
545                     "sort$0.java",
546                     ACC_PUBLIC | ACC_SUPER | ACC_FINAL,
547                     new String  [] {},
548                     classGen.getStylesheet());
549     
550     final ConstantPoolGen cpg = sortRecord.getConstantPool();   
551 
552     // Add a new instance variable for each var in closure
553     final int nsorts = sortObjects.size();
554     final ArrayList   dups = new ArrayList  ();
555 
556     for (int j = 0; j < nsorts; j++) {
557         final Sort sort = (Sort) sortObjects.get(j);
558 
559         // Set the name of the inner class in this sort object
560         sort.setInnerClassName(className);  
561 
562         final int length = (sort._closureVars == null) ? 0 : 
563         sort._closureVars.size();
564         for (int i = 0; i < length; i++) {
565         final VariableRefBase varRef = (VariableRefBase) sort._closureVars.get(i);
566 
567         // Discard duplicate variable references
568         if (dups.contains(varRef)) continue;
569 
570         final VariableBase var = varRef.getVariable();
571         sortRecord.addField(new Field(ACC_PUBLIC, 
572                     cpg.addUtf8(var.getEscapedName()),
573                     cpg.addUtf8(var.getType().toSignature()),
574                     null, cpg.getConstantPool()));
575         dups.add(varRef);
576         }
577     }
578 
579     Method init = compileInit(sortObjects, sortRecord,
580                      cpg, className);
581     Method extract = compileExtract(sortObjects, sortRecord,
582                     cpg, className);
583     sortRecord.addMethod(init);
584     sortRecord.addMethod(extract);
585 
586     xsltc.dumpClass(sortRecord.getJavaClass());
587     return className;
588     }
589 
590     /**
591      * Create a constructor for the new class. Updates the reference to the 
592      * collator in the super calls only when the stylesheet specifies a new
593      * language in xsl:sort.
594      */
595     private static Method compileInit(Vector   sortObjects,
596                        NodeSortRecordGenerator sortRecord,
597                        ConstantPoolGen cpg,
598                        String   className) 
599     {
600     final InstructionList il = new InstructionList();
601     final MethodGenerator init = 
602         new MethodGenerator(ACC_PUBLIC, 
603                 org.apache.bcel.generic.Type.VOID, 
604                 null, null, "<init>", className, 
605                 il, cpg);
606 
607     // Call the constructor in the NodeSortRecord superclass
608     il.append(ALOAD_0);
609     il.append(new INVOKESPECIAL(cpg.addMethodref(NODE_SORT_RECORD,
610                              "<init>", "()V")));
611 
612     
613 
614     il.append(RETURN);
615 
616     init.stripAttributes(true);
617     init.setMaxLocals();
618     init.setMaxStack();
619 
620     return init.getMethod();
621     }
622 
623 
624     /**
625      * Compiles a method that overloads NodeSortRecord.extractValueFromDOM()
626      */
627     private static Method compileExtract(Vector   sortObjects,
628                      NodeSortRecordGenerator sortRecord,
629                      ConstantPoolGen cpg,
630                      String   className) {
631     final InstructionList il = new InstructionList();
632     
633     // String NodeSortRecord.extractValueFromDOM(dom,node,level);
634     final CompareGenerator extractMethod =
635         new CompareGenerator(ACC_PUBLIC | ACC_FINAL,
636                  org.apache.bcel.generic.Type.STRING, 
637                  new org.apache.bcel.generic.Type[] {
638                              Util.getJCRefType(DOM_INTF_SIG),
639                      org.apache.bcel.generic.Type.INT,
640                      org.apache.bcel.generic.Type.INT,
641                      Util.getJCRefType(TRANSLET_SIG),
642                      org.apache.bcel.generic.Type.INT
643                  },
644                  new String  [] { "dom",
645                         "current",
646                         "level",
647                         "translet",
648                         "last"
649                  },
650                  "extractValueFromDOM", className, il, cpg);
651 
652     // Values needed for the switch statement
653     final int levels = sortObjects.size();
654     final int match[] = new int[levels];
655     final InstructionHandle target[] = new InstructionHandle[levels];
656     InstructionHandle tblswitch = null;
657 
658     // Compile switch statement only if the key has multiple levels
659     if (levels > 1) {
660         // Put the parameter to the swtich statement on the stack
661         il.append(new ILOAD(extractMethod.getLocalIndex("level")));
662         // Append the switch statement here later on
663         tblswitch = il.append(new NOP());
664     }
665 
666     // Append all the cases for the switch statment
667     for (int level = 0; level < levels; level++) {
668         match[level] = level;
669         final Sort sort = (Sort)sortObjects.elementAt(level);
670         target[level] = il.append(NOP);
671         sort.translateSelect(sortRecord, extractMethod);
672         il.append(ARETURN);
673     }
674     
675     // Compile def. target for switch statement if key has multiple levels
676     if (levels > 1) {
677         // Append the default target - it will _NEVER_ be reached
678         InstructionHandle defaultTarget =
679         il.append(new PUSH(cpg, EMPTYSTRING));
680         il.insert(tblswitch,new TABLESWITCH(match, target, defaultTarget));
681         il.append(ARETURN);
682     }
683 
684     extractMethod.stripAttributes(true);
685     extractMethod.setMaxLocals();
686     extractMethod.setMaxStack();
687     extractMethod.removeNOPs();
688 
689     return extractMethod.getMethod();
690     }
691 }
692
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