Python StateMachine.get_epsilon_closure方法代碼示例

# 需要導入模塊: from quex.engine.state_machine.core import StateMachine [as 別名]
# 或者: from quex.engine.state_machine.core.StateMachine import get_epsilon_closure [as 別名]
def do(SM_List):
    """Intersection: 

       Only match on patterns which are matched by all state machines
       in 'SM_List'.

       (C) 2013 Frank-Rene Schaefer
       ________________________________________________________________________

       A lexeme which matches all patterns must reach an acceptance in each 
       given state machine. That is, 
       
          For each state machine; there is a path from the init 
          state to an acceptance state triggered along the by 
          the characters of the lexeme.

       We cannot go forward, since we cannot omit a path upon non-fit.

       Now, consider the super-state consisting of all acceptance states
       of all state machines. There there must be a way backward from the 
       super-acceptance-state to the init state states. As soon, as a
       path is interupted, it can be thrown away. This can be achieved
       by reversed state machines which are combined into a single one.
       
       Reverse all state machines; The epsilon closure of the init state
       corresponds to the super acceptance state. The transitions in the
       super-state machine correspond to the way backwards in the state
       machine. For each feasible state in the super-state machine create
       a new state. 

       The acceptance state of the reversed state machines correspond to 
       the init state of the original state machines. If the super state
       contains an acceptance state of the original state, it can become
       an acceptance state of the intersection, because we now found a 
       path. The found state machine must be reversed at the end.

    """
    for sm in SM_List:
        if special.is_none(sm):         # If one state machine is '\None'
            return special.get_none()   # then, the intersection is '\None'

    reverse_sm_list          = [ reverse.do(sm)                            for sm in SM_List ]
    state_id_set_list        = [ set(sm.states.iterkeys())                 for sm in reverse_sm_list ]
    acceptance_state_id_list = [ set(sm.get_acceptance_state_index_list()) for sm in reverse_sm_list ]

    def has_one_from_each(StateIDSet_List, StateIDSet):
        """StateIDSet_List[i] is the set of state indices from state 
        machine 'i' in 'reverse_sm_list'. 

        RETURNS: True -- If the StateIDSet has at least one state 
                         from every state machine.
                 False -- If there is at least one state machine 
                          that has no state in 'StateIDSet'.
        """
        for state_id_set in StateIDSet_List:
            if state_id_set.isdisjoint(StateIDSet): 
                return False
        return True

    def get_merged_state(AcceptanceStateIndexList, EpsilonClosure):
        """Create the new target state in the state machine
           Accept only if all accept.
        """
        acceptance_f = has_one_from_each(AcceptanceStateIndexList, 
                                         EpsilonClosure)
        return State(AcceptanceF=acceptance_f)

    # Plain merge of all states of all state machines with an 
    # epsilon transition from the init state to all init states
    # of the reverse_sm
    sm = StateMachine()
    for rsm in reverse_sm_list:
        sm.states.update(rsm.states)
        sm.add_epsilon_transition(sm.init_state_index, rsm.init_state_index) 

    initial_state_epsilon_closure = sm.get_epsilon_closure(sm.init_state_index) 

    InitState = get_merged_state(acceptance_state_id_list, 
                                 initial_state_epsilon_closure)

    result    = StateMachine(InitStateIndex=index.get(), InitState=InitState)

    # (*) prepare the initial worklist
    worklist = [ ( result.init_state_index, initial_state_epsilon_closure) ]

    epsilon_closure_db = sm.get_epsilon_closure_db()

    while len(worklist) != 0:
        # 'start_state_index' is the index of an **existing** state in the state machine.
        # It was either created above, in StateMachine's constructor, or as a target
        # state index.
        start_state_index, start_state_combination = worklist.pop()
 
        # (*) compute the elementary trigger sets together with the 
        #     epsilon closure of target state combinations that they trigger to.
        #     In other words: find the ranges of characters where the state triggers to
        #     a unique state combination. E.g:
        #                Range        Target State Combination 
        #                [0:23]   --> [ State1, State2, State10 ]
        #                [24:60]  --> [ State1 ]
#.........這裏部分代碼省略.........