def grammar_from_file(self, grammar):
"""
Reads in a CFG from a given file, converts it to CNF and stores it in self.grammar.
:param grammar: the file in which the grammar is stored.
"""
self.grammar = grammar_converter.convert_grammar(
grammar_converter.read_grammar(grammar))
def grammar_from_string(self, grammar):
"""
Reads in a CFG from a string, converts it to CNF and stores it in self.grammar.
:param grammar: the CFG in string representation.
:return:
"""
self.grammar = grammar_converter.convert_grammar(
[x.replace("->", "").split() for x in grammar.split("\n")])
def __init__(self, sentence):
"""
Creates a new parser object which will read in the grammar and transform it into CNF and
then parse the given sentence with that grammar.
:param grammar: the file path to the grammar/the string repr. of the grammar to read in
:param sentence: the file path to the sentence/the string repr. of the sentence to read in
"""
self.parse_table = None
self.prods = {}
self.grammar = grammar_converter.convert_grammar(
grammar_converter.read_grammar("CFG.txt"))
with open('CNF.txt', 'w') as cnf:
for item in self.grammar:
cnf.write("%s\n" % item)
# self.__call__(sentence)
with open(sentence) as inp:
self.inputline = [line.strip() for line in inp if line.strip()]
# this returns list
incorrect = False
for i in range(len(self.inputline)):
#self.input = re.findall(r"[\w']+|[.,():=]", self.inputline[i])
self.input = self.inputline[i].split()
# print(self.input)
self.parse()
# self.print_tree2()
start_symbol = self.grammar[0][0]
final_nodes = [
n for n in self.parse_table[-1][0] if n.symbol == start_symbol
]
# print(final_nodes)
if not final_nodes:
print("Syntax error")
print(" " + self.inputline[i])
incorrect = True
# break
if not incorrect:
print("Accepted")
def grammar_from_file(self, grammar):
self.grammar = grammar_converter.convert_grammar(
grammar_converter.read_grammar(grammar))