nxt.container.bimap source code

1 module nxt.container.bimap;
2 
3 @safe pure:
4 
5 /** Bidirectional map between key-and-values of type `X` and `Y` inspired by C++
6     Boost Bimap (`boost::bimap`). Map-type defaults to a builtin associative
7     array (AA).
8 
9     See_Also: http://www.boost.org/doc/libs/1_65_1/libs/bimap/doc/html/boost_bimap/one_minute_tutorial.html
10  */
11 struct BiMap(X, Y, alias Map = Y[X])
12 {
13 @safe pure nothrow:
14     alias LeftMap = Map!(X, Y);
15     alias RightMap = Map!(Y, X);
16 
17     /// Insert (`x`, `y`).
18     void insert(X x, Y y)
19     {
20         pragma(inline, true);
21         _left[x] = y;
22         _right[y] = x;
23     }
24 
25     /// Check if (`x`, `y`) is stored.
26     bool contains(scope const X x,
27                   scope const Y y) const
28     {
29         version(LDC) pragma(inline, true);
30         // TODO: do this symmetric?
31         if (const hitPtr = x in _left)
32             return *hitPtr == y;
33         return false;
34     }
35 
36     /// Clear contents.
37     void clear() @trusted       // TODO: ok for this to be `@trusted`?
38     {
39         version(D_Coverage) {} else pragma(inline, true);
40         _left.clear();
41         _right.clear();
42     }
43 
44     /// Check if empty.
45     bool empty() const @property @nogc => length == 0;
46     /// Get length.
47     size_t length() const @nogc => _left.length;
48     /// Access to left map must be non-mutating.
49     ref const(LeftMap) left() const @nogc => _left;
50     /// Access to right map must be non-mutating.
51     ref const(RightMap) right() const @nogc => _right;
52 private:
53     LeftMap _left;              ///< Left map.
54     RightMap _right;            ///< Right map.
55 }
56 
57 /// test with builtin associative arrays
58 @safe pure nothrow unittest
59 {
60     alias HashMap(Key, Value) = Value[Key];
61     BiMap!(size_t, string, HashMap) bm;
62 
63     bm.insert(42, "42");
64 
65     assert(bm.left.length == 1);
66     assert(bm.right.length == 1);
67 
68     assert(bm.contains(42, "42"));
69 
70     bm.clear();
71     assert(bm.empty);
72 }