magicstatemachines/util.rs
1use crate::{In, State, StateMachineImpl, StateStorage, StateUnionDiscriminant};
2
3/// Convenience extension for converting a state into a union's generated enum.
4///
5/// This is implemented for every generated union marker. It is most useful
6/// when the marker value is already in scope and you want the concrete enum
7/// immediately, without spelling the associated [`In`](crate::In) conversion
8/// and then calling `discriminate()` yourself:
9///
10/// ```ignore
11/// use magicstatemachines::EnumExt;
12/// use test_def::{Online, OnlineEnum};
13///
14/// let online = Online.into_enum(state);
15///
16/// match online {
17/// OnlineEnum::Connected(connected) => {
18/// // `connected` has the concrete `Connected` state marker.
19/// }
20/// OnlineEnum::Authenticated(authenticated) => {
21/// // `authenticated` has the concrete `Authenticated` state marker.
22/// }
23/// }
24/// ```
25pub trait EnumExt: StateUnionDiscriminant {
26 /// Converts `state` into this union's generated enum.
27 ///
28 /// The input state may be any concrete state that implements `In<Self>`.
29 /// The output is the enum associated with this marker, for example
30 /// `OnlineEnum<S, Connection>` for marker `Online`.
31 fn into_enum<S, T, Current>(
32 self,
33 state: State<S, T, Current>,
34 ) -> <Self as StateUnionDiscriminant>::Enum<S, T>
35 where
36 S: StateStorage,
37 T: StateMachineImpl,
38 Current: In<Self>,
39 {
40 <Current as In<Self>>::into_discriminated(state).discriminate()
41 }
42}
43
44impl<T: StateUnionDiscriminant> EnumExt for T {}