def all_suffixes(self, fsa: pynini.Fst) -> pynini.Fst:
fsa = fsa.copy()
start_state = fsa.start()
for s in fsa.states():
fsa.add_arc(
start_state,
pynini.Arc(0, 0, pynini.Weight.one(fsa.weight_type()), s))
return fsa.optimize()
def _flip_lemmatizer_feature_labels(self,
lemmatizer: pynini.Fst) -> pynini.Fst:
"""Helper function to flip lemmatizer's feature labels from input to output.
Destructive operation.
Args:
lemmatizer: FST representing a partially constructed lemmatizer.
Returns:
Modified lemmatizer.
"""
feature_labels = set()
for s in self.category.feature_labels.states():
aiter = self.category.feature_labels.arcs(s)
while not aiter.done():
arc = aiter.value()
if arc.ilabel:
feature_labels.add(arc.ilabel)
aiter.next()
lemmatizer.set_input_symbols(lemmatizer.output_symbols())
for s in lemmatizer.states():
maiter = lemmatizer.mutable_arcs(s)
while not maiter.done():
arc = maiter.value()
if arc.olabel in feature_labels:
# This assertion should always be true by construction.
assert arc.ilabel == 0, (
f"ilabel = "
f"{lemmatizer.input_symbols().find(arc.ilabel)},"
f" olabel = "
f"{lemmatizer.output_symbols().find(arc.olabel)}")
arc = pynini.Arc(arc.olabel, arc.ilabel, arc.weight,
arc.nextstate)
maiter.set_value(arc)
maiter.next()
return lemmatizer
def _narcs(f: pynini.Fst) -> int:
"""Computes the number of arcs in an FST."""
return sum(f.num_arcs(state) for state in f.states())
def all_prefixes(self, fsa: pynini.Fst) -> pynini.Fst:
fsa = fsa.copy()
for s in fsa.states():
fsa.set_final(s)
return fsa.optimize()