1#
2# vending_machine.py
3#
4# Example of using the statemachine parser without importing a .pystate module.
5#
6# A vending machine that dispenses candy and chips in a 4x4 grid, A1 thru D4.
7# To dispense a product, you must press an alpha button, then a digit button.
8#
9
10import statemachine
11
12# Vending machine buttons:
13#    A, B, C, D
14#    1, 2, 3, 4
15#
16vending_machine_state_description = """\
17statemachine VendingMachineState:
18    Idle-(press_alpha_button)->WaitingOnDigit
19    WaitingOnDigit-(press_alpha_button)->WaitingOnDigit
20    WaitingOnDigit-(press_digit_button)->DispenseProduct
21    DispenseProduct-(dispense)->Idle
22"""
23
24# convert state machine text to state classes
25generated = statemachine.namedStateMachine.transformString(
26    vending_machine_state_description
27)
28# print(generated)
29# exec generated code to define state classes and state mixin
30exec(generated)
31
32
33class VendingMachine(VendingMachineStateMixin):
34    def __init__(self):
35        self.initialize_state(Idle)
36        self._pressed = None
37        self._alpha_pressed = None
38        self._digit_pressed = None
39
40    def press_button(self, button):
41        if button in "ABCD":
42            self._pressed = button
43            self.press_alpha_button()
44        elif button in "1234":
45            self._pressed = button
46            self.press_digit_button()
47        else:
48            print("Did not recognize button {!r}".format(str(button)))
49
50    def press_alpha_button(self):
51        try:
52            super().press_alpha_button()
53        except VendingMachineState.InvalidTransitionException as ite:
54            print(ite)
55        else:
56            self._alpha_pressed = self._pressed
57
58    def press_digit_button(self):
59        try:
60            super().press_digit_button()
61        except VendingMachineState.InvalidTransitionException as ite:
62            print(ite)
63        else:
64            self._digit_pressed = self._pressed
65            self.dispense()
66
67    def dispense(self):
68        try:
69            super().dispense()
70        except VendingMachineState.InvalidTransitionException as ite:
71            print(ite)
72        else:
73            print("Dispensing at {}{}".format(self._alpha_pressed, self._digit_pressed))
74            self._alpha_pressed = self._digit_pressed = None
75
76
77vm = VendingMachine()
78for button in "1 A B 1".split():
79    print(">> pressing {!r}".format(button))
80    vm.press_button(button)
81    print("Vending machine is now in {} state".format(vm.state))
82