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1
19
20 package edu.umd.cs.findbugs.ba.npe2;
21
22 import java.util.BitSet  ;
23
24 import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
25 import edu.umd.cs.findbugs.ba.vna.ValueNumber;
26
27
32 public class DefinitelyNullSet {
33 private BitSet contents;
34 private int numValueNumbers;
35
36 public DefinitelyNullSet(int numValueNumbers) {
37 this.contents = new BitSet ();
38 this.numValueNumbers = numValueNumbers;
39 }
40
41 public NullnessValue getNulllessValue(ValueNumber valueNumber) {
42 return getNullnessValue(valueNumber.getNumber());
43 }
44
45 private NullnessValue getNullnessValue(int vn) {
46 int flags = 0;
47
48 int start = getStartIndex(vn);
49 for (int i = 0; i < NullnessValue.FLAGS_MAX; i++) {
50 if (contents.get(start + i)) {
51 flags |= (1 << i);
52 }
53 }
54
55 return NullnessValue.fromFlags(flags);
56 }
57
58 public void setNullnessValue(ValueNumber valueNumber, NullnessValue nullnessValue) {
59 int flags = nullnessValue.getFlags();
60
61 int start = getStartIndex(valueNumber.getNumber());
62 for (int i = 0; i < NullnessValue.FLAGS_MAX; i++) {
63 contents.set(start + i, (flags & (1 << i)) != 0);
64 }
65 }
66
67 public void clear() {
68 contents.clear();
69 }
70
71 public void setTop() {
72 contents.clear();
73 contents.set(lastUsedBit());
74 }
75
76 public boolean isTop() {
77 return contents.get(lastUsedBit());
78 }
79
80 public void setBottom() {
81 contents.clear();
82 contents.set(lastUsedBit() + 1);
83 }
84
85 public boolean isBottom() {
86 return contents.get(lastUsedBit() + 1);
87 }
88
89 public boolean isValid() {
90 return !(isTop() || isBottom());
91 }
92
93 public void makeSameAs(DefinitelyNullSet other) {
94 contents.clear();
95 contents.or(other.contents);
96 }
97
98 public void mergeWith(DefinitelyNullSet other) {
99 if (this.isBottom() || other.isTop()) {
100 return;
101 }
102
103 if (this.isTop() || other.isBottom()) {
104 this.makeSameAs(other);
105 return;
106 }
107
108 this.contents.and(other.contents);
110 }
111
112 public BitSet getAssignedNullLocationSet(ValueNumber vn) {
113 throw new UnsupportedOperationException ();
114 }
115
116 public void addAssignedNullLocation(int valueNumber, int locationNumber) {
117 }
119
120 public void clearAssignNullLocations(int valueNumber) {
121 }
123
124 private int getStartIndex(int vn) {
125 return vn * (1 << NullnessValue.FLAGS_MAX);
126 }
127
128 private int lastUsedBit() {
129 return numValueNumbers * NullnessValue.FLAGS_MAX;
130 }
131
132 private int topBit() {
133 return lastUsedBit();
134 }
135
136 private int bottomBit() {
137 return lastUsedBit() + 1;
138 }
139
140
143 @Override
144 public int hashCode() {
145 return contents.hashCode();
146 }
147
148
151 @Override
152 public boolean equals(Object obj) {
153 if (obj == null || obj.getClass() != this.getClass()) {
154 return false;
155 }
156
157 DefinitelyNullSet other = (DefinitelyNullSet) obj;
158 return this.contents.equals(other.contents);
159 }
160
161
164 @Override
165 public String toString() {
166 if (isTop()) {
167 return "[TOP]";
168 } else if (isBottom()) {
169 return "[BOTTOM]";
170 } else {
171 StringBuffer buf = new StringBuffer ();
172 boolean first = true;
173
174 buf.append("{");
175
176 for (int i = 0; i < numValueNumbers; i++) {
177 NullnessValue val = getNullnessValue(i);
178 if (val.isDefinitelyNull() || val.isDefinitelyNotNull()) {
179 if (first) {
180 first = false;
181 } else {
182 buf.append(", ");
183 }
184 buf.append(i);
185 buf.append("->");
186 buf.append(val.toString());
187 }
188 }
189
190 buf.append("}");
191
192 return buf.toString();
193 }
194 }
195 }
196 |
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