QuestionableBooleanAssignment


1   /*
2    * FindBugs - Find bugs in Java programs
3    * Copyright (C) 2005 Dave Brosius <dbrosius@users.sourceforge.net>
4    * Copyright (C) 2005 University of Maryland
5    * 
6    * This library is free software; you can redistribute it and/or
7    * modify it under the terms of the GNU Lesser General Public
8    * License as published by the Free Software Foundation; either
9    * version 2.1 of the License, or (at your option) any later version.
10   * 
11   * This library is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   * Lesser General Public License for more details.
15   * 
16   * You should have received a copy of the GNU Lesser General Public
17   * License along with this library; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19   */
20  package edu.umd.cs.findbugs.detect;
21  
22  
23  import edu.umd.cs.findbugs.*;
24  import org.apache.bcel.classfile.Code;
25  
26  public class QuestionableBooleanAssignment extends BytecodeScanningDetector implements StatelessDetector
27  {
28      public static final int SEEN_NOTHING = 0;
29      public static final int SEEN_ICONST_0_OR_1 = 1;
30      public static final int SEEN_DUP = 2;
31      public static final int SEEN_ISTORE = 3;
32      public static final int SEEN_GOTO = 4;
33      public static final int SEEN_IF = 5;
34      
35      private BugReporter bugReporter;
36      private int state;
37      
38      private BugInstance bug;
39      public QuestionableBooleanAssignment(BugReporter bugReporter) {
40          this.bugReporter = bugReporter;
41      }
42  
43  
44      
45      @Override  
46           public void visitCode(Code obj) {
47          state = SEEN_NOTHING;
48          super.visitCode(obj);
49          bug = null;
50      }
51      
52      @Override  
53           public void sawOpcode(int seen) {
54          if (seen == GOTO && getBranchOffset() == 4) {
55              state = SEEN_GOTO;
56          }
57          else switch (state) {
58              case SEEN_NOTHING:
59                  if ((seen == ICONST_1) || (seen == ICONST_0))
60                      state = SEEN_ICONST_0_OR_1;
61              break;
62              
63              case SEEN_ICONST_0_OR_1:
64                  if (seen == DUP)
65                      state = SEEN_DUP;
66                  else
67                      state = SEEN_NOTHING;
68              break;
69              
70              case SEEN_DUP:
71                  if (((seen >= ISTORE_0) && (seen <= ISTORE_3)) || (seen == ISTORE))
72                      state = SEEN_ISTORE;
73                  else
74                      state = SEEN_NOTHING;
75              break;
76              
77              case SEEN_ISTORE: 
78                  if (seen == IFEQ || seen == IFNE)
79                  {
80                      bug = new BugInstance( this, "QBA_QUESTIONABLE_BOOLEAN_ASSIGNMENT", HIGH_PRIORITY)
81                          .addClassAndMethod(this)
82                          .addSourceLine(this);
83                      state = SEEN_IF;
84                  }
85                  else state = SEEN_NOTHING;
86              break;
87              
88  
89              case SEEN_IF:
90                  state = SEEN_NOTHING;
91                  if (seen == NEW) {
92                      String   cName = getClassConstantOperand();
93                      if (cName.equals("java/lang/AssertionError")) break;
94                  }
95                  bugReporter.reportBug(bug);
96                  
97                      
98                  break;
99              case SEEN_GOTO:
100                 state = SEEN_NOTHING;
101                 break;
102         }
103     }
104 }
105
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