simplesm 0.1.4

simplesm

Simple state machine for python 3 that use dictionaries for creating states.

Installation

pip3 install simplesm

Documents

SimpleSM subclasses would have:

Machine states dict values could have:

Machine first tries to match action string against current state transitions, if not found one, then tries to call each current state transition and if it return True that transition will be accepted.

Usage and Features With Example

Import SimpleSM from simplesm and create a class:

from simplesm import SimpleSM


class TestMachine(SimpleSM):
    start_state = "S0"
    states = {
        "S0": {"transitions": {
            "0": {"state": "S1", "event": "print"},
            "1": {"state": "S2", "event": "print"}
        }, "event": "welcome"},
        "S1": {"final": False, "transitions": {
            "1": {"state": "S0", "event": "print"}
        }, "event": "welcome"},
        "S2": {"final": True, "transitions": {
            "0": {"state": "S1", "event": "print"},
            "2": {"state": "S3", "event": "print"},
            "is_a_to_d": {"state": "S0", "event": "print"}
        }, "else": "s2_wrong", "event": "welcome"},
        "S3": {"event": "goto_s2"}
    }

    def goto_s2(self):
        print("we are just going to state S2")
        self.current_state = "S2"

    def welcome(self):
        print("we are in state {0} and get action {1}".format(self.current_state, self.test_action))

    def print(self):
        print("going from {0} to {1} with {2}".format(self.previous_state, self.current_state, self.current_action))

    def s2_wrong(self):
        print("unacceptable input {0}".format(self.test_action))
        self.current_state = "Error"

    def is_a_to_d(self):
        if self.test_action in "abcd":
            return True
        return False


def main():
    m = TestMachine()
    m.perform(list("0110112a1d011"))
    print("current state is",m.current_state,"before calling accept")
    print("does machine accept 0110112a1d011 ?", m.accept(list("0110112a1d011")))
    print("current state is",m.current_state,"after calling accept")
    print("current state is acceptable ?", m.is_acceptable)


if __name__ == '__main__':
    main()

output:

we are in state S0 and get action 0
going from S0 to S1 with 0
we are in state S1 and get action 1
going from S1 to S0 with 1
we are in state S0 and get action 1
going from S0 to S2 with 1
we are in state S2 and get action 0
going from S2 to S1 with 0
we are in state S1 and get action 1
going from S1 to S0 with 1
we are in state S0 and get action 1
going from S0 to S2 with 1
we are in state S2 and get action 2
going from S2 to S3 with 2
we are just going to state S2
going from S2 to S0 with a
we are in state S0 and get action 1
going from S0 to S2 with 1
we are in state S2 and get action d
going from S2 to S0 with d
we are in state S0 and get action 0
going from S0 to S1 with 0
we are in state S1 and get action 1
going from S1 to S0 with 1
we are in state S0 and get action 1
going from S0 to S2 with 1
current state is S2 before calling accept
does machine accept 0110112a1d011 ? False
current state is S2 after calling accept
current state is acceptable ? True