def parse(self, tokenizer, state=None):
from token import Token
lookahead = None
lookaheadstack = []
statestack = [0]
symstack = [Token("$end", "$end")]
current_state = 0
while True:
if self.lr_table.default_reductions[current_state]:
t = self.lr_table.default_reductions[current_state]
current_state = self._reduce_production(
t, symstack, statestack, state)
continue
if lookahead is None:
if lookaheadstack:
lookahead = lookaheadstack.pop()
else:
try:
lookahead = next(tokenizer)
except StopIteration:
lookahead = None
if lookahead is None:
lookahead = Token("$end", "$end")
ltype = lookahead.gettokentype()
if ltype in self.lr_table.lr_action[current_state]:
t = self.lr_table.lr_action[current_state][ltype]
if t > 0:
statestack.append(t)
current_state = t
symstack.append(lookahead)
lookahead = None
continue
elif t < 0:
current_state = self._reduce_production(
t, symstack, statestack, state)
continue
else:
n = symstack[-1]
return n
else:
# TODO: actual error handling here
if self.error_handler is not None:
if state is None:
self.error_handler(lookahead)
else:
self.error_handler(state, lookahead)
raise AssertionError("For now, error_handler must raise.")
else:
raise ParsingError(None, lookahead.getsourcepos())
