antlr.v4.runtime.atn.ContextMapObjectEqualityComparator source code

1 module antlr.v4.runtime.atn.ContextMapObjectEqualityComparator;
2 
3 import antlr.v4.runtime.atn.ATNConfig;
4 import antlr.v4.runtime.misc.MurmurHash;
5 
6 /**
7  * TODO add class description
8  */
9 class ContextMapObjectEqualityComparator
10 {
11 
12     /**
13      * The single instance of ContextMapObjectEqualityComparator.
14      */
15     private static __gshared ContextMapObjectEqualityComparator instance_;
16 
17     public static bool opEquals(Object a, Object b)
18     {
19         if (a is b) {
20             return true;
21         } else
22             if (b is null || a is null) {
23                 return false;
24             }
25         auto objA = cast(ATNConfig)a;
26         auto objB = cast(ATNConfig)b;
27         return objA.state.stateNumber == objA.state.stateNumber
28             && (objA.context is objB.context ||
29                 (objA.context !is null && objB.context !is null &&
30                  objA.context.opEquals(objB.context)));
31     }
32 
33     /**
34      * @uml
35      * @trusted
36      * @nothrow
37      */
38     public static size_t toHash(Object o) @trusted nothrow
39     {
40         if (cast(ATNConfig)o)
41             {
42                 auto obj = cast(ATNConfig)o;
43                 size_t hashCode = MurmurHash.initialize(7);
44                 hashCode = MurmurHash.update(hashCode, obj.state.stateNumber);
45                 hashCode = MurmurHash.update(hashCode, obj.context);
46                 hashCode = MurmurHash.finish(hashCode, 2);
47                 return hashCode;
48             }
49         return false;
50     }
51 
52     /**
53      * Creates the single instance of ContextMapObjectEqualityComparator.
54      */
55     private shared static this()
56     {
57         instance_ = new ContextMapObjectEqualityComparator;
58     }
59 
60     /**
61      * Returns: A single instance of ContextMapObjectEqualityComparator.
62      */
63     public static ContextMapObjectEqualityComparator instance()
64     {
65         return instance_;
66     }
67 
68 }