Skip to content

Latest commit

 

History

History
45 lines (35 loc) · 1.47 KB

README.md

File metadata and controls

45 lines (35 loc) · 1.47 KB
Raw

scala-fsm

Finite state machine (FSM) implemented in Scala. State transitions are being checked in compile-time, which means that invalid transitions will not compile.

Usage

See the unit tests for more example usages. Here is an example:

  • Define your states
    case class A(id: String) extends State
    case class B(id: String) extends State
    case class C(id: String) extends State
  • Define your inputs
    case class Iab(id: String) extends Input
    case class Iac(id: String) extends Input
    case class Ibc(id: String) extends Input
  • Define your transitions
    implicit val tAB = Transformation[A, Iab, B]((a, e) => B(a.id + e.id)
    implicit val tAC = Transformation[A, Iac, C]((a, e) => C(a.id + e.id))
    implicit val tBC = Transformation[B, Ibc, C]((b, e) => C(b.id + e.id))
    implicit def tCC[E <: Input] = Transformation[C, E, C]((c, e) => C(c.id + "i"))
  • Then you can transition between stages:
    Fsm(A("a")).transition(Iab("b")) shouldBe Fsm(B("ab"))
    Fsm(A("a")).transition(Iac("c")) shouldBe Fsm(C("ac"))
    Fsm(B("b")).transition(Ibc("c")) shouldBe Fsm(C("bc"))

    Fsm(C("c")).transition(Iab("")) shouldBe Fsm(C("ci"))
    Fsm(C("c")).transition(Iab("")).transition(Iac("")).transition(Ibc("")) shouldBe Fsm(C("ciii"))

    // Invalid transition won't compile
    // Fsm(A("a")).transition(Ibc(""))

License

Code released under the Apache License 2.0.