Finite is a simple, pure Swift finite state machine. Only exlicitly allowed transitions between states are allowed, otherwise an error will be thrown.
| Finite | Swift |
|---|---|
2.0.0 |
2.2 and 3.0 Beta |
3.x.x |
3.0 and 4.0 |
4.x.x |
5.0 |
Finite has no external dependencies and supports Swift Package Manager, Carthage and CocoaPods.
import PackageDescription
let package = Package(
name: "YourPackage",
dependencies: [
.package(url: "https://github.com/vknabel/Finite.git", from: "4.0.0")
],
targets: [
.target(name: "YourTarget", dependencies: ["Finite"]),
]
)github "vknabel/Finite"source 'https://github.com/CocoaPods/Specs.git'
use_frameworks!
pod 'Finite', '~> 4.0.0'It operates on a given type, where each value represents an internal state of the machine. A StateMachine is defined by providing all allowed state transitions.
enum Test: Int {
case saving, fetching, deleting
case ready, fail
}
var machine = StateMachine<Test>(initial: .ready) { c in
c.allow(from: [.saving, .fetching, .deleting], to: [.ready, .fail])
c.allow(from: .ready, to: [.saving, .fetching, .deleting])
}It is possible to provide callbacks, that will be called once certain transitions will happen.
machine.onTransitions {
println("Successfully triggered transition!")
}
machine.onTransitions(from: .ready) {
println("From Ready: show activity indicator")
}
machine.onTransitions(to: .ready) {
println("To Ready: hide activity indicator")
}
machine.onTransitions(to: .saving) {
println("To: save")
}
let subscription = machine.subscribeTransitions(to: .saving) {
println("Only triggered as long as you keep `subscription`")
}Once the StateMachine has been set up, you may trigger all transitions you have declared above.
try machine.transition(to: .saving) {
println("Triggered: save")
}
// this will throw TransitionError<Test>.denied(from: .saving, to: .fetching)
try machine.transition(to: .fetching)Valentin Knabel, dev@vknabel.com
Special thanks to @snofla for allowing to export state machines to graphviz.
Finite is available under the MIT license.