levee 1.0.0

Create state machines with a visually pleasing syntax

Levee

Create state machines with a visually pleasing syntax in Python

Remember, keep your Levee DRY!

Example Usage

For more examples of what you can do, read the tests

from levee import Chart, State, Condition, Effect

class FlowChart(Chart):
    class ALPHA(State): pass
    class BETA(State): pass
    class GAMMA(State): pass

    class Sometimes(Condition):

        def eval(self, sometimes):
            return sometimes
    
    class Maybe(Condition):

        def eval(self, maybe):
            # Return a string to block the transition with a reason
            return maybe if maybe else 'I guess not'

    class PrintWhatever(Effect):

        def exec(self, whatever):
            # Parameter names in the definition of Condition.eval/Effect.exec will become
            # required named arguments for Chart.to/Chart.can/Chart.choices
            print(whatever)
    
    class SayHello(Effect):
        
        def exec(self):
            print('Hello!')

    chart = {
        ALPHA: {
            BETA (Sometimes) [PrintWhatever]: ...,
            GAMMA (Sometimes | Maybe) [SayHello]: ...,
        },
        BETA: {
            ALPHA (Sometimes & Maybe) [PrintWhatever + PrintWhatever]: ...,
        },
        GAMMA: {
            ALPHA (~Maybe) [PrintWhatever + SayHello]: ...,
        }
    }

def main():
    data = { 'state': None }
    chart = FlowChart(data)
    print(chart.state, chart.choices(sometimes=True, maybe=False, whatever='whatever'))
    chart.to(FlowChart.BETA, sometimes=True, whatever='Whatever Once')
    chart.to(FlowChart.ALPHA, sometimes=True, maybe=True, whatever='Whatever Twice')
    if chart.can(FlowChart.GAMMA, sometimes=False, maybe=True):
      chart.to(FlowChart.GAMMA, sometimes=False, maybe=True)
    chart.to(FlowChart.ALPHA, maybe=False, whatever='Goodbye!')