local function call(func, ...)
    if func then 
        return func(...)
    end
end

function jin.core.run()
    call(jin.core.onLoad)
    local dt = 0
    local previous = jin.time.second()
    local current = previous
    -- TODO: 重写，事件处理事件应该高频率调用
    while jin.core.running() do
        for _, e in pairs(jin.event.poll()) do 
            if e.type == "keydown" then 
                jin.keyboard.set(e.key, true) 
            elseif e.type == "keyup" then 
                jin.keyboard.set(e.key, false)
            end
            call(jin.core.onEvent, e)
        end

        previous = current
        current = jin.time.second() 
        dt = current - previous

        call(jin.core.onUpdate, dt)

        if jin.graphics then 
            jin.graphics.unbindCanvas() 
            jin.graphics.clear() 
            jin.graphics.setColor()
            jin.graphics.setFont()
            call(jin.core.onDraw)
            jin.graphics.present()
        end     
        
        if jin.time then 
            jin.time.sleep(0.001)
        end     
    end
end