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class State:
'''
A representation of a state managed by a ``StateMachine``.
Attributes:
name (instance of FreeGroupElement or string) -- State name which is also assigned to the Machine.
transisitons (OrderedDict) -- Represents all the transitions of the state object.
state_type (string) -- Denotes the type (accept/start/dead) of the state.
rh_rule (instance of FreeGroupElement) -- right hand rule for dead state.
state_machine (instance of StateMachine object) -- The finite state machine that the state belongs to.
'''
def __init__(self, name, state_machine, state_type=None, rh_rule=None):
self.name = name
self.transitions = {}
self.state_machine = state_machine
self.state_type = state_type[0]
self.rh_rule = rh_rule
def add_transition(self, letter, state):
'''
Add a transition from the current state to a new state.
Keyword Arguments:
letter -- The alphabet element the current state reads to make the state transition.
state -- This will be an instance of the State object which represents a new state after in the transition after the alphabet is read.
'''
self.transitions[letter] = state
class StateMachine:
'''
Representation of a finite state machine the manages the states and the transitions of the automaton.
Attributes:
states (dictionary) -- Collection of all registered `State` objects.
name (str) -- Name of the state machine.
'''
def __init__(self, name, automaton_alphabet):
self.name = name
self.automaton_alphabet = automaton_alphabet
self.states = {} # Contains all the states in the machine.
self.add_state('start', state_type='s')
def add_state(self, state_name, state_type=None, rh_rule=None):
'''
Instantiate a state object and stores it in the 'states' dictionary.
Arguments:
state_name (instance of FreeGroupElement or string) -- name of the new states.
state_type (string) -- Denotes the type (accept/start/dead) of the state added.
rh_rule (instance of FreeGroupElement) -- right hand rule for dead state.
'''
new_state = State(state_name, self, state_type, rh_rule)
self.states[state_name] = new_state
def __repr__(self):
return "%s" % (self.name)
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