|
1
20
21 package edu.umd.cs.findbugs.detect;
22
23
24 import edu.umd.cs.findbugs.*;
25 import java.util.*;
26 import org.apache.bcel.classfile.*;
27
28
35 public class UnnecessaryMath extends BytecodeScanningDetector implements StatelessDetector {
36 static final int SEEN_NOTHING = 0;
37 static final int SEEN_DCONST = 1;
38
39 private BugReporter bugReporter;
40 private int state = SEEN_NOTHING;
41 private double constValue;
42
43 private static final Set<String  > zeroMethods = new HashSet<String >()
44 {{ add("acos");
45 add("asin");
46 add("atan");
47 add("atan2");
48 add("cbrt");
49 add("cos");
50 add("cosh");
51 add("exp");
52 add("expm1");
53 add("log");
54 add("log10");
55 add("pow");
56 add("sin");
57 add("sinh");
58 add("sqrt");
59 add("tan");
60 add("tanh");
61 add("toDegrees");
62 add("toRadians");
63 }};
64 private static final Set<String > oneMethods = new HashSet<String >()
65 {{ add("acos");
66 add("asin");
67 add("atan");
68 add("cbrt");
69 add("exp");
70 add("log");
71 add("log10");
72 add("pow");
73 add("sqrt");
74 add("toDegrees");
75 }};
76 private static final Set<String > anyMethods = new HashSet<String >()
77 {{ add("abs");
78 add("ceil");
79 add("floor");
80 add("rint");
81 add("round");
82 }};
83
84 public UnnecessaryMath(BugReporter bugReporter) {
85 this.bugReporter = bugReporter;
86 }
87
88
89
90 @Override
91 public void visit(Code obj) {
92 if (getMethod().getName().equals("<clinit>"))
95 return;
96
97 state = SEEN_NOTHING;
98 super.visit(obj);
99 }
100
101 @Override
102 public void sawOpcode(int seen) {
103 if (state == SEEN_NOTHING) {
104 if ((seen == DCONST_0) || (seen == DCONST_1)) {
105 constValue = (double) (seen - DCONST_0);
106 state = SEEN_DCONST;
107 }
108 else if ((seen == LDC2_W) || (seen == LDC_W)) {
109 state = SEEN_DCONST;
110 Constant c = this.getConstantRefOperand();
111 if (c instanceof ConstantDouble)
112 constValue = ((ConstantDouble)c).getBytes();
113 else if (c instanceof ConstantFloat)
114 constValue = ((ConstantFloat)c).getBytes();
115 else if (c instanceof ConstantLong)
116 constValue = ((ConstantLong)c).getBytes();
117 else
118 state = SEEN_NOTHING;
119 }
120 } else if (state == SEEN_DCONST) {
121 if (seen == INVOKESTATIC) {
122 state = SEEN_NOTHING;
123 if (getDottedClassConstantOperand().equals("java.lang.Math")) {
124 String methodName = getNameConstantOperand();
125
126 if (((constValue == 0.0) && zeroMethods.contains(methodName))
127 || ((constValue == 1.0) && oneMethods.contains(methodName))
128 || (anyMethods.contains(methodName))) {
129 bugReporter.reportBug(new BugInstance("UM_UNNECESSARY_MATH", LOW_PRIORITY)
130 .addClassAndMethod(this)
131 .addSourceLine(this));
132 }
133 }
134 }
135 state = SEEN_NOTHING;
136 }
137 }
138 }
139
140 |
Popular Tags |
Java API By Example, From Geeks To Geeks.