def goto(self, grammar, symbol):
new_grammar = Context_Free_Grammar()
for LHS in grammar.production:
for production in grammar.production[LHS]:
index = production.index('.') + 1
if index < len(production) and production[index] == symbol:
index += 1
if index < len(production) and production[
index] in self.augmented_grammar.non_terminal:
new_grammar = self.track(grammar, new_grammar,
production[index])
new_production = deepcopy(production)
new_production.insert(
new_production.index('.') + 1,
new_production.pop(new_production.index('.')))
new_grammar.add_production_rule(LHS, new_production)
for a_symbol in list(set([LHS] + production)):
new_grammar = self.set_symbol(new_grammar, a_symbol)
return new_grammar
def Grammar():
grammar = Context_Free_Grammar()
grammar.add_terminal('+', '*', '(', ')', 'id')
grammar.add_non_terminal('E', 'T', 'F')
grammar.set_start_symbol('E')
grammar.add_production_rule('E', ['E', '+', 'T'], ['T'])
grammar.add_production_rule('T', ['T', '*', 'F'], ['F'])
grammar.add_production_rule('F', ['(', 'E', ')'], ['id'])
return grammar
def Grammar():
grammar = Context_Free_Grammar()
grammar.add_terminal('a', 'b', 'c', '~', ':', 'author', 'title')
grammar.add_non_terminal('Text', 'Effect', 'Alpha')
grammar.set_start_symbol('Text')
grammar.add_production_rule('Text', ['~', 'Effect', ':', 'Text', '~'],
['Alpha'])
grammar.add_production_rule('Effect', ['author'], ['title'])
grammar.add_production_rule('Alpha', ['a'], ['b'])
#grammar.add_production_rule('F', ['(', 'E', ')'], ['id'])
return grammar
