def test_case_4(self):
grammar = Grammar()
grammar.init_min_length()
grammar.parse("""
S -> A B
A -> a b
B -> c
""")
result = parse_with_unger(grammar, 'abc')
self.assertEqual(result, ('A B', ('a b', 'a', 'b'), ('c', 'c')))
def test_grammar_min_length(self):
grammar = Grammar()
grammar.parse("""
Number -> Integer | Real
Integer -> Digit | Integer Digit
Real -> Integer Fraction Scale
Fraction -> . Integer
Scale -> e Sign Integer | Empty
Digit -> 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
Sign -> + | -
Empty -> ε
""")
grammar.init_min_length()
self.assertEqual(0, grammar.symbols['Scale'].min_length)
self.assertEqual(1, grammar.symbols['Number'].min_length)
self.assertEqual(2, grammar.symbols['Fraction'].min_length)
self.assertEqual(3, grammar.symbols['Real'].min_length)