JSONParser.save

1 auto json = JSONParser(q{
2     [
3         {
4             "name": "A",
5             "ability": "doFoo",
6             "health": 30
7         },
8         {
9             "name": "B",
10             "ability": "doBar"
11         },
12         {
13             "name": "C",
14             "inherits": ["A", "B"],
15             "ability": "doTest"
16         }
17     ]
18 });
19 
20 static class EntityMeta {
21     string name;
22     string[] inherits;
23 }
24 
25 static class Entity : EntityMeta {
26     string ability;
27     int health = 100;
28 }
29 
30 JSONParser[string] states;
31 Entity[string] entities;
32 foreach (index; json.getArray) {
33 
34     // Get the metadata and save the state
35     auto state = json.save;
36     auto meta = json.getStruct!EntityMeta;  // Efficient and quick way to fetch the two attributes
37     states[meta.name] = state.save;
38 
39     // Create the object
40     auto entity = new Entity();
41 
42     // Inherit properties
43     foreach (parent; meta.inherits) {
44 
45         // Get the parent
46         auto parentState = states[parent].save;
47 
48         // Inherit its values
49         parentState.updateStruct(entity);
50         // Note: We're operating on classes. Use `entity = state.getStruct(entity)` on structs
51 
52     }
53 
54     // Now, add local data
55     state.updateStruct(entity);
56 
57     entities[entity.name] = entity;
58 
59 }
60 
61 const a = entities["A"];
62 assert(a.name == "A");
63 assert(a.ability == "doFoo");
64 assert(a.health == 30);
65 
66 const b = entities["B"];
67 assert(b.name == "B");
68 assert(b.ability == "doBar");
69 assert(b.health == 100);
70 
71 const c = entities["C"];
72 assert(c.name == "C");
73 assert(c.ability == "doTest");
74 assert(c.health == 30);  // A had explicitly stated health, B did not — inherited from A.
75                          // Otherwise impossible without saving states.
76