State

1 interface TestCommand
2 {
3 	TestCommand command(string cmd) @safe;
4 	TestCommand update() @safe;
5 }
6 string msg;
7 
8 TestCommand test1;
9 TestCommand test2;
10 
11 static struct StatePolicy
12 {
13 	alias Commands = TestCommand;
14 	alias ExitChildHandler = void delegate(Commands);
15 }
16 static struct FlowPolicy
17 {
18 	alias Commands = TestCommand;
19 	alias EnterChildHandler = void delegate(Commands, Commands);
20 }
21 test1 = new class State!StatePolicy
22 {
23 	override TestCommand command(string cmd)
24 	{
25 		msg = cmd;
26 		// not transit
27 		return super.command(cmd);
28 	}
29 	override TestCommand update()
30 	{
31 		msg = "";
32 		// transit to child(test2)
33 		setNext(test2);
34 		return super.update();
35 	}
36 };
37 test2 = new class State!TestCommand
38 {
39 	override TestCommand command(string cmd)
40 	{
41 		msg = cmd ~ "!";
42 		// not transit
43 		return super.command(cmd);
44 	}
45 	override TestCommand update()
46 	{
47 		msg = "!";
48 		// transit to parent(test1)
49 		setNext(test1);
50 		return super.update();
51 	}
52 };
53 
54 auto sts = new Flow!FlowPolicy(test1);
55 
56 // not transit
57 sts.command("test");
58 assert(msg == "test");
59 
60 // transit to child(test2)
61 sts.update();
62 assert(msg == "");
63 
64 // not transit
65 sts.command("test");
66 assert(msg == "test!");
67 
68 // transit to parent(test1)
69 sts.update();
70 assert(msg == "!");
71 
72 // not transit
73 sts.command("test");
74 assert(msg == "test");