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Java > Open Source Codes > edu > umd > cs > findbugs > detect > FindFieldSelfAssignment


1 /*
2  * FindBugs - Find bugs in Java programs
3  * Copyright (C) 2003-2005 University of Maryland
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with this library; if not, write to the Free Software
17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18  */
19
20 package edu.umd.cs.findbugs.detect;
21
22
23 import java.util.HashSet JavaDoc;
24 import java.util.Iterator JavaDoc;
25 import java.util.Set JavaDoc;
26
27 import org.apache.bcel.classfile.Code;
28
29 import edu.umd.cs.findbugs.BugInstance;
30 import edu.umd.cs.findbugs.BugReporter;
31 import edu.umd.cs.findbugs.BytecodeScanningDetector;
32 import edu.umd.cs.findbugs.StatelessDetector;
33 import edu.umd.cs.findbugs.ba.SignatureParser;
34
35 public class FindFieldSelfAssignment extends BytecodeScanningDetector implements StatelessDetector {
36     private BugReporter bugReporter;
37     int state;
38
39
40     public FindFieldSelfAssignment(BugReporter bugReporter) {
41         this.bugReporter = bugReporter;
42     }
43     
44
45
46     @Override JavaDoc
47          public void visit(Code obj) {
48         state = 0;
49         super.visit(obj);
50         initializedFields.clear();
51     }
52
53
54     String JavaDoc f;
55     String JavaDoc className;
56     Set JavaDoc<String JavaDoc> initializedFields = new HashSet JavaDoc<String JavaDoc>();
57
58     @Override JavaDoc
59          public void sawOpcode(int seen) {
60
61         switch (state) {
62         case 0:
63             if (seen == ALOAD_0)
64                 state = 1;
65             break;
66         case 1:
67             if (seen == ALOAD_0)
68                 state = 2;
69             else
70                 state = 0;
71             break;
72         case 2:
73             if (seen == GETFIELD) {
74                 state = 3;
75                 f = getRefConstantOperand();
76                 className = getClassConstantOperand();
77             } else
78                 state = 0;
79             break;
80         case 3:
81             if (seen == PUTFIELD && getRefConstantOperand().equals(f) && getClassConstantOperand().equals(className)) {
82
83                 int priority = NORMAL_PRIORITY;
84                 SignatureParser parser = new SignatureParser(getMethodSig());
85                 boolean foundMatch = false;
86                 for(Iterator JavaDoc<String JavaDoc> i = parser.parameterSignatureIterator(); i.hasNext(); ) {
87                     String JavaDoc s = i.next();
88                     if (s.equals(getSigConstantOperand())) {
89                         foundMatch = true;
90                         break;
91                     }
92                 }
93                 if (getMethodName().equals("<init>") && !initializedFields.contains(getRefConstantOperand()) && foundMatch)
94                     priority = HIGH_PRIORITY;
95             
96                 bugReporter.reportBug(new BugInstance(this, "SA_FIELD_SELF_ASSIGNMENT", priority)
97                         .addClassAndMethod(this)
98                         .addReferencedField(this)
99                         .addSourceLine(this));
100             }
101             state = 0;
102         }
103         
104         if (seen == PUTFIELD && getClassConstantOperand().equals(className))
105             initializedFields.add(getRefConstantOperand());
106
107     }
108
109 }
110
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