def test_derive(a, b):
# Just some basic tests because this is mainly a regex thing.
assert a.derive("a") == epsilon({"a", "b"})
assert a.derive("b") == null({"a", "b"})
try:
a.derive("c")
assert False
except KeyError:
assert True
assert (a * 3).derive("a") == a * 2
assert (a.star() - epsilon({"a", "b"})).derive("a") == a.star()
def to_fsm(self, alphabet=None):
if alphabet is None:
alphabet = self.alphabet()
fsm1 = fsm.epsilon(alphabet)
for m in self.mults:
fsm1 += m.to_fsm(alphabet)
return fsm1
def test_concatenation_aa(a):
concAA = a + a
assert not concAA.accepts("")
assert not concAA.accepts("a")
assert concAA.accepts("aa")
assert not concAA.accepts("aaa")
concAA = epsilon({"a", "b"}) + a + a
assert not concAA.accepts("")
assert not concAA.accepts("a")
assert concAA.accepts("aa")
assert not concAA.accepts("aaa")
def to_fsm(self, alphabet=None):
if alphabet is None:
alphabet = self.alphabet()
unit = self.multiplicand.to_fsm(alphabet)
mandatory = unit * self.multiplier.mandatory.bound
if self.multiplier.optional == Bound(None):
optional = unit.star()
else:
optional = fsm.epsilon(alphabet) | unit
optional *= self.multiplier.optional.bound
return (mandatory + optional)
def test_optional_mul(a, b):
unit = a + b
# accepts "ab"
optional = (epsilon(a.alphabet) | unit)
# accepts "(ab)?"
assert optional.accepts([])
assert not optional.accepts(["a"])
assert not optional.accepts(["b"])
assert optional.accepts(["a", "b"])
assert not optional.accepts(["a", "a"])
optional = optional * 2
# accepts "(ab)?(ab)?"
assert optional.accepts([])
assert not optional.accepts(["a"])
assert not optional.accepts(["b"])
assert not optional.accepts(["a", "a"])
assert optional.accepts(["a", "b"])
assert not optional.accepts(["b", "a"])
assert not optional.accepts(["b", "b"])
assert not optional.accepts(["a", "a", "a"])
assert optional.accepts(["a", "b", "a", "b"])
def test_concatenate_bug(a):
# This exposes a defect in fsm.concatenate.
assert FSM.concatenate(a, epsilon({"a"}), a).accepts("aa")
assert FSM.concatenate(a, epsilon({"a"}), epsilon({"a"}), a).accepts("aa")
def test_builtins():
assert not null("a").accepts("a")
assert epsilon("a").accepts("")
assert not epsilon("a").accepts("a")
def test_reverse_epsilon():
# epsilon reversed is epsilon
assert reversed(epsilon("a")).accepts("")