def test_functions_follow_empty(self):
expected = follow(self.follow_empty, 'B')
self.assertTrue(len(expected) == 1)
self.assertTrue('c' in expected)
expected = follow(self.follow_empty, 'C')
self.assertTrue(expected == follow(self.follow_empty, 'B'))
def test_functions_no_empty_grammar(self):
expected = follow(self.no_empty, 'B')
self.assertTrue(len(expected) == 1)
self.assertTrue('a' in expected)
expected = follow(self.no_empty, 'C')
self.assertTrue(expected == follow(self.no_empty, 'B'))
def test_right_recursive_epsilon(self):
expected = follow(self.right_recursive_epsilon, 'T')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.right_recursive_epsilon.EOF in expected)
expected = follow(self.right_recursive_epsilon, 'E')
self.assertTrue(len(expected) == 2)
self.assertTrue(')' in expected)
self.assertTrue(self.right_recursive_epsilon.EOF in expected)
def test_right_recursive_epsilon(self):
expected = follow(self.right_recursive_epsilon, 'T')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.right_recursive_epsilon.EOF in expected)
expected = follow(self.right_recursive_epsilon, 'E')
self.assertTrue(len(expected) == 2)
self.assertTrue(')' in expected)
self.assertTrue(self.right_recursive_epsilon.EOF in expected)
def test_left_recursive(self):
expected = follow(self.left_recursive, 'T')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.left_recursive.EOF in expected)
expected = follow(self.left_recursive, 'E')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.left_recursive.EOF in expected)
def test_left_recursive(self):
expected = follow(self.left_recursive, 'T')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.left_recursive.EOF in expected)
expected = follow(self.left_recursive, 'E')
self.assertTrue(len(expected) == 4)
self.assertTrue('+' in expected)
self.assertTrue('-' in expected)
self.assertTrue(')' in expected)
self.assertTrue(self.left_recursive.EOF in expected)
def test_functions_twolevels_grammar(self):
expected = first(self.twolevels, ['A'])
self.assertTrue(len(expected) == 1)
self.assertTrue('c' in expected)
expected = first(self.twolevels, ['B'])
self.assertTrue(len(expected) == 1)
self.assertTrue(self.twolevels.EMPTY in expected)
expected = follow(self.twolevels, 'B')
self.assertTrue(len(expected) == 1)
self.assertTrue('c' in expected)
expected = follow(self.twolevels, 'M')
self.assertTrue(expected == follow(self.twolevels, 'B'))
def test_simple(self):
expected = follow(self.simple, 'A')
self.assertTrue(len(expected) == 3)
self.assertTrue('a' in expected)
self.assertTrue('b' in expected)
self.assertTrue('s' in expected)
expected = follow(self.simple, 'B')
self.assertTrue(len(expected) == 2)
self.assertTrue('b' in expected)
self.assertTrue('s' in expected)
expected = follow(self.simple, 'S')
self.assertTrue(len(expected) == 1)
self.assertTrue(self.simple.EOF in expected)
def test_simple(self):
expected = follow(self.simple, 'A')
self.assertTrue(len(expected) == 3)
self.assertTrue('a' in expected)
self.assertTrue('b' in expected)
self.assertTrue('s' in expected)
expected = follow(self.simple, 'B')
self.assertTrue(len(expected) == 2)
self.assertTrue('b' in expected)
self.assertTrue('s' in expected)
expected = follow(self.simple, 'S')
self.assertTrue(len(expected) == 1)
self.assertTrue(self.simple.EOF in expected)
def test_lr_value_with_actions(self):
expected = follow(self.lrvalue_with_actions, 'S')
self.assertTrue(len(expected) == 2)
self.assertTrue(')' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
expected = follow(self.lrvalue_with_actions, 'L')
self.assertTrue(len(expected) == 3)
self.assertTrue(')' in expected)
self.assertTrue('=' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
expected = follow(self.lrvalue_with_actions, 'R')
self.assertTrue(len(expected) == 3)
self.assertTrue(')' in expected)
self.assertTrue('=' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
def test_functions_simple_grammar(self):
expected = first(self.simple, ['A'])
self.assertTrue(len(expected) == 1)
self.assertTrue('a' in expected)
expected = follow(self.simple, 'M')
self.assertTrue(len(expected) == 1)
self.assertTrue('a' in expected)
def test_lr_value_with_actions(self):
expected = follow(self.lrvalue_with_actions, 'S')
self.assertTrue(len(expected) == 2)
self.assertTrue(')' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
expected = follow(self.lrvalue_with_actions, 'L')
self.assertTrue(len(expected) == 3)
self.assertTrue(')' in expected)
self.assertTrue('=' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
expected = follow(self.lrvalue_with_actions, 'R')
self.assertTrue(len(expected) == 3)
self.assertTrue(')' in expected)
self.assertTrue('=' in expected)
self.assertTrue(self.lrvalue_with_actions.EOF in expected)
def test_bug_missing_terminals_found_by_follow_algorithm(self):
'''The problem is due the 'follow' algorithm assumes that if
a rule has the nonterminal X, the rules has only one X.
Obviously, this is not true in general.
'''
found = follow(self.grammar, 'expr')
self.assertTrue({'NL', 'NUM'} & found) #found by the 'first' algorithm
self.assertTrue({'+', '-'} & found) #found by the 'follow' algorithm
self.assertTrue(frozenset(['NUM', 'NL', '+', '-']) == found)
def test_bug_missing_terminals_found_by_follow_algorithm(self):
'''The problem is due the 'follow' algorithm assumes that if
a rule has the nonterminal X, the rules has only one X.
Obviously, this is not true in general.
'''
found = follow(self.grammar, 'expr')
self.assertTrue({'NL', 'NUM'} & found) #found by the 'first' algorithm
self.assertTrue({'+', '-'} & found) #found by the 'follow' algorithm
self.assertTrue(frozenset(['NUM', 'NL', '+', '-']) == found)
def test_more_complex(self):
expected = follow(self.more_complex, 'A')
self.assertTrue(len(expected) == 1)
self.assertTrue('q' in expected)
expected = follow(self.more_complex, 'B')
self.assertTrue(len(expected) == 1)
self.assertTrue('r' in expected)
expected = follow(self.more_complex, 'S')
self.assertTrue(len(expected) == 1)
self.assertTrue(self.more_complex.EOF in expected)
expected = follow(self.more_complex, 'C')
self.assertTrue(len(expected) == 1)
self.assertTrue('a' in expected)
expected = follow(self.more_complex, 'D')
self.assertTrue(len(expected) == 1)
self.assertTrue('b' in expected)
def test_more_complex(self):
expected = follow(self.more_complex, 'A')
self.assertTrue(len(expected) == 1)
self.assertTrue('q' in expected)
expected = follow(self.more_complex, 'B')
self.assertTrue(len(expected) == 1)
self.assertTrue('r' in expected)
expected = follow(self.more_complex, 'S')
self.assertTrue(len(expected) == 1)
self.assertTrue(self.more_complex.EOF in expected)
expected = follow(self.more_complex, 'C')
self.assertTrue(len(expected) == 1)
self.assertTrue('a' in expected)
expected = follow(self.more_complex, 'D')
self.assertTrue(len(expected) == 1)
self.assertTrue('b' in expected)
def followers(self, grammar):
return follow(grammar, self.sym_production)
