Rust 中简单的有限状态机库。提供状态和事件类型（通常是枚举），然后生成一个具有初始状态的状态机，给它一些转换行为，你就有了你的状态机！

使用方法

使用来自 FSM 维基百科条目的简单投币式旋转门示例

定义你的状态和事件

// states and events must be C-like enums (copyable and easily converted to primitives)
#[derive(Copy, Clone)]
enum TurnStyleState {
	Locked,
	Unlocked,
}

#[derive(Copy, Clone)]
enum TurnStyleEvent {
	Push,
	InsertCoin,
}

// implement the EnumTag trait for states and events
impl EnumTag for TurnStyleState {
	fn tag_number(&self) -> usize {
		*self as usize
	}
	fn max_tag_number() -> usize {
		TurnStyleState::Unlocked as usize
	}
}

impl EnumTag for TurnStyleEvent {
	fn tag_number(&self) -> usize {
		*self as usize
	}
	fn max_tag_number() -> usize {
		TurnStyleEvent::InsertCoin as usize
	}
}

创建你的状态机并定义你的转换

// create the machine initially in the Locked state
let mut machine = Machine::new(TurnStyleState::Locked);
// create the transition from Locked -> Unlocked upon inserting a coin
machine.add_transition(
	TurnStyleState::Locked, TurnStyleEvent::InsertCoin,
	TurnStyleState::Unlocked, |_,_| println!("unlocked")
);
// create the transition from Unlocked -> Locked upon pushing the turnstyle
machine.add_transition(
	TurnStyleState::Unlocked, TurnStyleEvent::Push,
	TurnStyleState::Locked, |_,_| println!("locked")
);

按需触发事件，然后出发

// initially we're in the Locked state
machine.on_event(TurnStyleEvent::InsertCoin);
// now we're Unlocked, ("unlocked" was just printed)
machine.on_event(TurnStyleEvent::Push);
// now we're Locked again, ("locked" was just printed)

此示例也是库的测试用例，尽管这里省略了测试相关的细节。

待办事项

• 公开谓词接口并为其编写单元测试

替代方案

基于宏的解决方案

• machine
• microstate
• beehave

其他

• genfsm