def _parser(it):
expected = set([])
v, it = primitives.any_(it)
did_advance = False
# This is a bookkeeping function that will mark did_advance if we indeed
# advanced the iterator.
def _wrap_advance(it):
nonlocal did_advance
did_advance = True
yield from it
for parser in parsers:
try:
return parser(itertools.chain([v], _wrap_advance(it)))
except primitives.ParseError as e:
# If the parser state was advanced, we throw the original error.
if did_advance:
raise
v = e.value
it = e.it
expected.update(e.expected)
raise primitives.ParseError(v, it, expected)
def _parser(it):
v, it = primitives.any_(it)
did_advance = False
# This is a bookkeeping function that will mark did_advance if we indeed
# advanced the iterator.
def _wrap_advance(it):
nonlocal did_advance
did_advance = True
yield from it
try:
v, it = parser(itertools.chain([v], _wrap_advance(it)))
except primitives.ParseError as e:
# If the parsing state was advanced, throw an error.
if did_advance:
raise
v = default()
it = e.unpeek()
return v, it