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