CreateClassField


1   /* CreateClassField Copyright (C) 1999-2002 Jochen Hoenicke.
2    *
3    * This program is free software; you can redistribute it and/or modify
4    * it under the terms of the GNU Lesser General Public License as published by
5    * the Free Software Foundation; either version 2, or (at your option)
6    * any later version.
7    *
8    * This program is distributed in the hope that it will be useful,
9    * but WITHOUT ANY WARRANTY; without even the implied warranty of
10   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11   * GNU General Public License for more details.
12   *
13   * You should have received a copy of the GNU Lesser General Public License
14   * along with this program; see the file COPYING.LESSER.  If not, write to
15   * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
16   *
17   * $Id: CreateClassField.java,v 1.8.2.2 2002/05/28 17:34:08 hoenicke Exp $
18   */
19  
20  package jode.flow;
21  import jode.expr.*;
22  import jode.type.Type;
23  import jode.decompiler.LocalInfo;
24  
25  public class CreateClassField {
26  
27  
28      public static boolean transform(IfThenElseBlock ifBlock,
29                      StructuredBlock last) {
30      // convert
31      //   if (class$classname == null)
32      //       class$classname = class$("java.lang.Object");
33      // to
34      //   if (classname.class == null) {
35      //   }
36          if (!(ifBlock.cond instanceof CompareUnaryOperator)
37          || !(((Operator)ifBlock.cond)
38           .getOperatorIndex() == Operator.EQUALS_OP)
39          || !(ifBlock.thenBlock instanceof InstructionBlock)
40          || ifBlock.elseBlock != null)
41              return false;
42  
43      if (ifBlock.thenBlock.jump != null 
44          && (ifBlock.jump == null
45          || (ifBlock.jump.destination 
46              != ifBlock.thenBlock.jump.destination)))
47          return false;
48  
49      CompareUnaryOperator cmp = (CompareUnaryOperator) ifBlock.cond;
50      Expression instr = 
51          ((InstructionBlock)ifBlock.thenBlock).getInstruction();
52      if (!(cmp.getSubExpressions()[0] instanceof GetFieldOperator)
53          || !(instr instanceof StoreInstruction))
54          return false;
55  
56      StoreInstruction store = (StoreInstruction) instr;
57      if (!(store.getLValue() instanceof PutFieldOperator))
58          return false;
59      PutFieldOperator put = (PutFieldOperator) store.getLValue();
60      if (put.getField() == null
61          || !put.matches((GetFieldOperator)cmp.getSubExpressions()[0])
62          || !(store.getSubExpressions()[1] instanceof InvokeOperator))
63          return false;
64  
65      InvokeOperator invoke = (InvokeOperator) store.getSubExpressions()[1];
66      if (!invoke.isGetClass())
67          return false;
68  
69      Expression param = invoke.getSubExpressions()[0];
70  
71      if (param instanceof ConstOperator
72          && ((ConstOperator)param).getValue() instanceof String  ) {
73          String   clazz = (String  ) ((ConstOperator)param).getValue();
74          if (put.getField().setClassConstant(clazz)) {
75          cmp.setSubExpressions
76              (0, new ClassFieldOperator(clazz.charAt(0) == '[' 
77                             ? Type.tType(clazz)
78                             : Type.tClass(clazz)));
79          EmptyBlock empty = new EmptyBlock();
80          empty.moveJump(ifBlock.thenBlock.jump);
81          ifBlock.setThenBlock(empty);
82          return true;
83          }
84      }
85      return false;
86      }
87  }
88
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