LINKDING

I've found myself coming back to this article several times when working on some hardware controller logic. Turns out Rust has some incredibly natural constructs for encoding state machines.

TL:DR Have a generically typed state machine struct. Encode the states in structs. Encode the allowed transitions between states using the From trait. For example,

// machine
struct Machine<S> {
  state: S
}

// states
struct State1
struct State2
struct State3

// transitions
//
// state 1 -> state 2 -> state 3
//    ^                     |
//    |_____________________|

// transition from state 1 to state 2.
impl From<Machine<State1>> for Machine<State2> {}

// transition from state 2 to state 3.
impl From<Machine<State2>> for Machine<State3> {}

// transition from state 3 to state 1.
impl From<Machine<State3>> for Machine<State1> {}