SwiftState状态机制

SwiftState 是用 Swift 编写的优雅的状态机制。

举例：

enum MyState: StateType {
    case state0, state1, state2
}

// setup state machine
let machine = StateMachine<MyState, NoEvent>(state: .state0) { machine in
    
    machine.addRoute(.state0 => .state1)
    machine.addRoute(.any => .state2) { context in print("Any => 2, msg=\(context.userInfo)") }
    machine.addRoute(.state2 => .any) { context in print("2 => Any, msg=\(context.userInfo)") }
    
    // add handler (`context = (event, fromState, toState, userInfo)`)
    machine.addHandler(.state0 => .state1) { context in
        print("0 => 1")
    }
    
    // add errorHandler
    machine.addErrorHandler { event, fromState, toState, userInfo in
        print("[ERROR] \(fromState) => \(toState)")
    }
}

// initial
XCTAssertEqual(machine.state, MyState.state0)

// tryState 0 => 1 => 2 => 1 => 0

machine <- .state1
XCTAssertEqual(machine.state, MyState.state1)

machine <- (.state2, "Hello")
XCTAssertEqual(machine.state, MyState.state2)

machine <- (.state1, "Bye")
XCTAssertEqual(machine.state, MyState.state1)

machine <- .state0  // fail: no 1 => 0
XCTAssertEqual(machine.state, MyState.state1)