有限

Finite 是一个简单的、纯 Swift 的有限状态机。只有显式允许的状态转换才被允许，否则会抛出错误。

有限	Swift
`2.0.0`	`2.2` 和 `3.0 Beta`
`3.x.x`	`3.0` 和 `4.0`
`4.x.x`	`5.0`

安装

Finite 没有外部依赖，并支持 Swift Package Manager、Carthage 和 CocoaPods。

Swift Package Manager

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"]),
    ]
)

Carthage

github "vknabel/Finite"

CocoaPods

source 'https://github.com/CocoaPods/Specs.git'
use_frameworks!

pod 'Finite', '~> 4.0.0'

介绍

它作用于给定的类型，其中每个值代表机器的内部状态。 StateMachine 通过提供所有允许的状态转换来定义。

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])
}

可以提供回调，这些回调将在某些转换发生时被调用。

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`")
}

一旦 StateMachine 被设置好，你就可以触发所有你在上面声明的转换。

try machine.transition(to: .saving) {
    println("Triggered: save")
}

// this will throw TransitionError<Test>.denied(from: .saving, to: .fetching)
try machine.transition(to: .fetching)

作者

Valentin Knabel, dev@vknabel.com

特别感谢 @snofla 允许将状态机导出到 graphviz。

许可证

Finite 在 MIT 许可证下可用。