1 module jar;
2
3 import std.array;
4 import std.typecons;
5
6 /// a container for registered types
7 class Jar {
8 private Object[][TypeInfo] _instance_registry;
9
10 /// register a type instance
11 public T register(T)(T instance) {
12 auto type = typeid(instance);
13 if (type !in _instance_registry) {
14 _instance_registry[type] = new Object[0];
15 }
16 _instance_registry[type] ~= instance;
17 return instance;
18 }
19
20 /// resolve all matching type instances
21 public T[] resolve_all(T)() {
22 auto type = typeid(T);
23 if (type in _instance_registry) {
24 Appender!(T[]) resolved;
25 foreach (item; _instance_registry[type]) {
26 resolved ~= cast(T) item;
27 }
28 return resolved.data;
29 }
30 return new T[0];
31 }
32
33 /// resolve first matching type instance
34 public Nullable!T resolve(T)() {
35 auto items = resolve_all!T();
36 if (items.length > 0) {
37 return Nullable!T(items[0]);
38 }
39 return Nullable!T.init;
40 }
41 }
42
43 unittest {
44 class Cookie {
45 bool delicious = true;
46 }
47
48 auto jar = new Jar();
49
50 auto c1 = new Cookie();
51 jar.register(c1);
52 auto r1 = jar.resolve!Cookie();
53 assert(!r1.isNull, "resolved item was null");
54 assert(r1.get() == c1, "resolved item did not match");
55
56 auto c2 = new Cookie();
57 jar.register(c2);
58
59 const auto cookies = jar.resolve_all!Cookie();
60 assert(cookies.length == 2, "mismatch in number of registered items");
61 }