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#!/usr/bin/env python
# Copyright: Ira W. Snyder
# Start Date: 2005-10-08
# End Date:
# License: Public Domain
#
# Changelog Follows:
# - 2005-10-16
# - Implemented the nfa class. It's mostly complete at this point.
# - E() function works for circular loops now.
# - Made the nfa.__next_states() function always return a valid reference
#   to a list in the dictionary. This means you should NEVER use
#   self.trans_func[(state, letter)] in code anywhere now :)
# - Final states are now checked for validity.
#

################################################################################
# IMPORTANT NOTES
################################################################################
################################################################################

import sys, string

class nfa:
    """Implements a Non-Deterministic Finite Automaton"""

    def __init__(self):
        self.trans_func = {}
        self.num_states = 0
        self.final_states = []
        self.initial_state = 0

    def __state_in_range(self, state):
        """Check if a given state is in the acceptable range"""

        try:
            temp = int(state)
        except (TypeError, ValueError):
            return False

        if temp >= 0 and temp < self.num_states:
            return True

        return False

    def __input_num_states(self):
        """Get the number of states this automaton will have"""

        done = False
        while not done:
            num_states = raw_input('How many states in this automaton: ')

            try:
                self.num_states = int(num_states)
                done = True
            except (TypeError, ValueError):
                print 'Bad input, not an integer, try again'
                print

    def __input_final_states(self):
        """Get final states for this automaton"""

        print 'Enter final states on one line, seperated by spaces'

        done = False
        while not done:
            final_states = raw_input('Final states: ')

            bad_data = False
            for i in final_states.split():
                if not self.__state_in_range(i):
                    print 'State %s out of range. All input discarded.' % (i, )
                    print 'Try again please'
                    print
                    bad_data = True
                    break

            # if we left the for loop with bad data
            if bad_data:
                continue

            # all data is good
            for i in final_states.split():
                if self.__state_in_range(i):
                    self.final_states.append(int(i))

            done = True

    def __input_all_edges(self):
        """Read all of the edges for this automaton"""

        print 'Edges take the form "from HERE, by LETTER, to THERE"'
        print 'Enter something like: "1 a 1" to represent the following'
        print 'from q1, by a, go to q1'
        print
        print 'Conditions:'
        print '1. Blank line to end'
        print '2. ^ is the empty string'

        done = False
        while not done:
            edge = raw_input('Edge: ')

            if len(edge) == 0:
                done = True
                continue

            if len(edge.split()) != 3:
                print 'Bad edge entered'
                print
                continue

            (cur_st, letter, next_st) = edge.split()

            # Make sure the states entered are in range
            if self.__state_in_range(cur_st) and self.__state_in_range(next_st):
                new_state = False
                cur_st = int(cur_st)
                next_st = int(next_st)

                # Add the state to the list if it's not there already
                if next_st not in self.__next_states(cur_st, letter):
                    self.__next_states(cur_st, letter).append(next_st)

            else:
                print 'Invalid current or next state entered'
                print
                continue

    def __input_automaton(self):
        """Read this entire automaton's input"""

        self.__input_num_states()
        self.__input_final_states()
        self.__input_all_edges()

    def main_menu(self):
        #NOTE: All of this code is not what it's supposed to be.
        #      It is for TESTING ONLY.
        #
        #TODO: Generate a menu :)

        self.__input_automaton()

        print self.trans_func
        print self.num_states
        print self.final_states
        print self.initial_state
        print

        for i in range(self.num_states):
            print 'E(%d): %s' % (i, self.__E(i))

    def __next_states(self, state, letter):
        """Return the next states for the key (state, letter)"""

        try:
            next = self.trans_func[(state, letter)]
        except KeyError:
            # Create a new empty list for this state if it doesn't exist yet
            next = self.trans_func[(state, letter)] = []

        if letter == '^' and state not in next:
            next.append(state)

        return next

    def __E(self, state, storage=None, visited=None):
        """Calculate E(state) and return it. This handles circular E()
        calculations."""

        # Work around weird mutable default argument stuff
        if storage is None:
            storage = []

        # Work around weird mutable default argument stuff
        if visited is None:
            visited = []

        # Find all of the direct next states that we can get to by
        # the empty string, and append anything that is not already there
        for i in self.__next_states(state, '^'):
            if i not in storage:
                storage.append(i)

        # Visit everything in storage that has not been visited already
        for i in storage:
            if i not in visited:
                visited.append(i)
                temp = self.__E(i, storage, visited)

                # Avoid duplicating things in storage
                for j in temp:
                    if j not in storage:
                        storage.append(j)

        return storage

    def output_dfa(self):
        #stuff here
        pass

if __name__ == '__main__':
    automaton = nfa()
    automaton.main_menu()