def re2a(er, trace=False):
S = Automaton()
name = {}
q0 = er.shift(True, None)
name[q0] = 0
nq0 = name[q0]
if trace:
sys.stderr.write("Initial state: %d\nItems:\n%s\n" % (nq0, q0))
S.addState(nq0, q0)
S.makeInitial(nq0)
if q0.isFinal():
S.makeFinal(nq0, q0.category())
pending = set([q0])
while len(pending) != 0:
q = pending.pop()
nq = name[q]
for charClass in q.movements():
d = q.shift(False, charClass)
if not name.has_key(d):
pending.add(d)
name[d] = len(name)
nd = name[d]
S.addState(nd, d)
if trace:
sys.stderr.write(
"Added state: %d%s, from %d with class %s\nItems:\n%s\n"
% (nd, d.isFinal() and " (final)"
or "", nq, charClass, d))
if d.isFinal():
S.makeFinal(nd, d.category())
nd = name[d]
S.addTransition(nq, charClass, nd)
S.compactArcs()
return S
