【Lua实战】协程实现状态机：把 if 地狱变成状态表

---协程驱动的状态机
function StateMachine.new(script)
    local sm = { co = coroutine.create(script) }
    function sm:fire(event)
        if coroutine.status(self.co) == "dead" then
            return false
        end
        local ok, wait = coroutine.resume(self.co, event)
        if not ok then
            ErrReport.push({ msg = tostring(wait) })
            return false
        end
        return true
    end
    return sm
end

---BOSS 战的流程脚本：线性书写
function BossFight.script()
    coroutine.yield("enter")
    Boss.say("竟敢闯入祖玛教主的领地！")
    coroutine.yield("phase1_dead")
    Boss.enrage()
    coroutine.yield("phase2_dead")
    Boss.die()
end

---带超时的等待：防流程卡死
function StateMachine.wait(self, event, timeout)
    local deadline = os.time() + (timeout or 300)
    while true do
        local ev = self:poll()
        if ev == event then return true end
        if os.time() > deadline then
            return false, "timeout"
        end
        coroutine.yield("tick")
    end
end

---任务的阶段脚本：三步交付
function Quest.script()
    local ok = StateMachine.wait(self, "accept")
    if not ok then return Quest.fail("未接取") end
    StateMachine.wait(self, "collected", 86400)
    StateMachine.wait(self, "submitted", 3600)
    Quest.reward()
end