def to_fsm(self, alphabet=None):
if alphabet is None:
alphabet = self.alphabet()
return reduce(lambda x, y: x | y,
map(lambda x: x.to_fsm(alphabet), self.concs),
fsm.null(alphabet))
def test_new_set_methods(a, b):
# A whole bunch of new methods were added to the FSM module to enable FSMs to
# function exactly as if they were sets of strings (symbol lists), see:
# https://docs.python.org/3/library/stdtypes.html#set-types-set-frozenset
# But do they work?
assert len(a) == 1
assert len((a | b) * 4) == 16
try:
len(a.star())
assert False
except OverflowError:
pass
# "in"
assert "a" in a
assert not "a" in b
assert "a" not in b
# List comprehension!
four = (a | b) * 2
for string in four:
assert string == ["a", "a"]
break
assert [s for s in four] == [["a", "a"], ["a", "b"], ["b", "a"],
["b", "b"]]
# set.union() imitation
assert FSM.union(a, b) == a.union(b)
assert len(FSM.union()) == 0
assert FSM.intersection(a, b) == a.intersection(b)
# This takes a little explaining. In general, `a & b & c` is equivalent to
# `EVERYTHING & a & b & c` where `EVERYTHING` is an FSM accepting every
# possible string. Similarly `a` is equivalent to `EVERYTHING & a`, and the
# intersection of no sets at all is... `EVERYTHING`.
# However, since we compute the union of alphabets, and there are no
# alphabets, the union is the empty set. So the only string which `EVERYTHING`
# actually recognises is the empty string, [] (or "" if you prefer).
int_none = FSM.intersection()
assert len(int_none) == 1
assert [] in int_none
assert (a | b).difference(a) == FSM.difference(
(a | b), a) == (a | b) - a == b
assert (a | b).difference(a, b) == FSM.difference(
(a | b), a, b) == (a | b) - a - b == null("ab")
assert a.symmetric_difference(b) == FSM.symmetric_difference(a, b) == a ^ b
assert a.isdisjoint(b)
assert a <= (a | b)
assert a < (a | b)
assert a != (a | b)
assert (a | b) > a
assert (a | b) >= a
assert list(a.concatenate(a, a).strings()) == [["a", "a", "a"]]
assert list(a.concatenate().strings()) == [["a"]]
assert list(FSM.concatenate(b, a, b).strings()) == [["b", "a", "b"]]
assert list(FSM.concatenate().strings()) == []
assert not a.copy() is a
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 test_builtins():
assert not null("a").accepts("a")
assert epsilon("a").accepts("")
assert not epsilon("a").accepts("a")
def test_alternation_a(a):
altA = a | null({"a", "b"})
assert not altA.accepts("")
assert altA.accepts("a")