def test_first_nt_02():
S = NonTerminal('S')
A = NonTerminal('A')
B = NonTerminal('B')
epsilon = Epsilon('&')
string = '''S -> A b | A B c
B -> b B | A d | &
A -> a A | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_first_nt()
expected_first_nt = {
S: set([A, B]),
B: set([epsilon, A]),
A: set([epsilon]),
}
assert g.first_nt == expected_first_nt
def test_follow_02():
a = Terminal('a')
b = Terminal('b')
c = Terminal('c')
e = Terminal('e')
eos = EoS('$')
string = '''S -> A C | C e B | B a
A -> a A | B C
C -> c C | &
B -> b B | A B | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_follow()
expected_follow = {
NonTerminal('S'): set([eos]),
NonTerminal('A'): set([a, b, c, eos]),
NonTerminal('C'): set([a, b, c, e, eos]),
NonTerminal('B'): set([a, b, c, eos]),
}
assert g.follow == expected_follow
def test_follow_01():
a = Terminal('a')
b = Terminal('b')
c = Terminal('c')
d = Terminal('d')
eos = EoS('$')
string = '''S -> A B C
A -> a A | &
B -> b B | A C d
C -> c C | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_follow()
expected_follow = {
NonTerminal('S'): set([eos]),
NonTerminal('A'): set([a, b, c, d]),
NonTerminal('B'): set([c, eos]),
NonTerminal('C'): set([d, eos])
}
assert g.follow == expected_follow
def test_first_of_string():
string = '''S -> A B C
A -> a A | &
B -> b B | A C d
C -> c C | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_first()
expected = set({Terminal('c'), Terminal('d')})
got = g.first_of_string([NonTerminal('C'), Terminal('d')])
assert got == expected
def test_first_01():
a = Terminal('a')
b = Terminal('b')
c = Terminal('c')
d = Terminal('d')
epsilon = Epsilon('&')
string = '''S -> A B C
A -> a A | &
B -> b B | A C d
C -> c C | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_first()
expected_first = {
NonTerminal('S'): set([a, b, c, d]),
NonTerminal('A'): set([a, epsilon]),
NonTerminal('B'): set([a, b, c, d]),
NonTerminal('C'): set([c, epsilon])
}
assert g.first == expected_first
def test_first_02():
a = Terminal('a')
b = Terminal('b')
c = Terminal('c')
e = Terminal('e')
epsilon = Epsilon('&')
string = '''S -> A C | C e B | B a
A -> a A | B C
C -> c C | &
B -> b B | A B | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_first()
expected_first = {
NonTerminal('S'): set([a, b, c, e, epsilon]),
NonTerminal('A'): set([a, b, c, epsilon]),
NonTerminal('C'): set([c, epsilon]),
NonTerminal('B'): set([a, b, c, epsilon]),
}
assert g.first == expected_first
def test_first_nt_01():
S = NonTerminal('S')
A = NonTerminal('A')
B = NonTerminal('B')
C = NonTerminal('C')
epsilon = Epsilon('&')
string = '''S -> A B C
A -> a A | &
B -> b B | A C d
C -> c C | &'''
g = ContextFreeGrammar.from_string(string)
g.calculate_first_nt()
expected_first_nt = {
S: set([A, B, C]),
A: set([epsilon]),
B: set([A, C]),
C: set([epsilon]),
}
assert g.first_nt == expected_first_nt
def test_n_sets():
g = ContextFreeGrammar.from_string('''
S -> F G H
F -> G | a
G -> d G | H | b
H -> c
''')
S, F, G, H = (NonTerminal(x) for x in 'SFGH')
expected = {
S: {S},
F: {F, G, H},
G: {G, H},
H: {H},
}
assert g.simple_production_sets() == expected