FlowGraph

// package.swift

import PackageDescription

let package = Package(
    name: "Sample",
    dependencies: [
        .package(url: "https://github.com/objective-audio/SwiftFlowGraph.git", from: "0.4.0")
    ],
    targets: [
        .target(
            name: "Sample",
            dependencies: ["FlowGraph"]),
    ]
)

import FlowGraph

class Door {
    private(set) var isOpen: Bool = false {
        didSet {
            print("isOpen \(self.isOpen)")
        }
    }

    enum EventKind {
        case open
        case close
    }

    typealias Event = (kind: EventKind, object: Door)

    private struct GraphType: FlowGraphType {
        enum WaitingState {
            case closed
            case opened
        }

        enum RunningState {
            case opening
            case closing
        }

        typealias Event = Door.Event
    }

    private var graph: FlowGraph<GraphType>

    init() {
        let builder = FlowGraphBuilder<GraphType>()

        builder.add(waiting: .closed) { event in
            if case .open = event.kind {
                return .run(.opening, event)
            } else {
                return .stay
            }
        }

        builder.add(waiting: .opened) { event in
            if case .close = event.kind {
                return .run(.closing, event)
            } else {
                return .stay
            }
        }

        builder.add(running: .opening) { event in
            event.object.isOpen = true
            return .wait(.opened)
        }

        builder.add(running: .closing) { event in
            event.object.isOpen = false
            return .wait(.closed)
        }

        self.graph = builder.build(initial: .closed)
    }

    func run(_ kind: EventKind) {
        self.graph.run((kind, self))
    }
}

let door = Door()

door.run(.open)

// 'isOpen true'

door.run(.close)

// 'isOpen false'

door.run(.close)

// Do nothing