1 package mockit.asm.constantPool;
2
3 import edu.umd.cs.findbugs.annotations.NonNull;
4 import edu.umd.cs.findbugs.annotations.Nullable;
5
6 import mockit.asm.jvmConstants.ConstantPoolTypes;
7
8 import org.checkerframework.checker.index.qual.NonNegative;
9
10 /**
11 * A constant pool item of a given {@linkplain ConstantPoolTypes type}.
12 */
13 public abstract class Item {
14 /**
15 * Index of this item in the constant pool.
16 */
17 @NonNegative
18 public final int index;
19
20 /**
21 * {@link ConstantPoolTypes Type} of this constant pool item.
22 * <p>
23 * MethodHandle variations are stored using a range of 9 values from {@link ConstantPoolTypes#HANDLE_BASE
24 * HANDLE_BASE} + 1 to {@link ConstantPoolTypes#HANDLE_BASE HANDLE_BASE} + 9.
25 * <p>
26 * Special Item types are used for items that are stored in the {@link ConstantPoolGeneration#typeTable}, instead of
27 * the constant pool, in order to avoid clashes with normal constant pool items in the constant pool's hash table.
28 * These special item types are defined in {@link TypeTableItem.SpecialType}.
29 */
30 @NonNegative
31 int type;
32
33 /**
34 * The hash code value of this constant pool item.
35 */
36 @NonNegative
37 private int hashCode;
38
39 /**
40 * Link to another constant pool item, used for collision lists in the constant pool's hash table.
41 */
42 @Nullable
43 private Item next;
44
45 /**
46 * Initializes an Item for a constant pool element at the given position.
47 *
48 * @param index
49 * index of the item
50 */
51 Item(@NonNegative int index) {
52 this.index = index;
53 }
54
55 /**
56 * Initializes this item as a copy of a given item.
57 *
58 * @param index
59 * index of the new item
60 * @param item
61 * the item to be copied into this item
62 */
63 Item(@NonNegative int index, @NonNull Item item) {
64 this.index = index;
65 type = item.type;
66 hashCode = item.hashCode;
67 }
68
69 /**
70 * Returns the {@link #type} of this item.
71 */
72 @NonNegative
73 public int getType() {
74 return type;
75 }
76
77 /**
78 * Returns the {@link #hashCode} value.
79 */
80 @NonNegative
81 public final int getHashCode() {
82 return hashCode;
83 }
84
85 final void setHashCode(int valuesHashCode) {
86 hashCode = 0x7FFFFFFF & type + valuesHashCode;
87 }
88
89 /**
90 * Returns the {@link #next} item, if any.
91 */
92 @Nullable
93 public Item getNext() {
94 return next;
95 }
96
97 public final void setNext(@NonNull Item[] items) {
98 int indexOfNextItem = hashCode % items.length;
99 next = items[indexOfNextItem];
100 items[indexOfNextItem] = this;
101 }
102
103 /**
104 * Indicates if the given item is equal to this one, <em>assuming that the two items have the same
105 * {@link #type}</em>.
106 *
107 * @param item
108 * the item to be compared to this one (both items must have the same {@link #type})
109 *
110 * @return <code>true</code> if the given item is equal to this one, <code>false</code> otherwise
111 */
112 abstract boolean isEqualTo(@NonNull Item item);
113 }