class W2lFairseqLMDecoder(W2lDecoder):
def __init__(self, args, tgt_dict):
super().__init__(args, tgt_dict)
self.unit_lm = getattr(args, "unit_lm", False)
self.lexicon = load_words(args.lexicon) if args.lexicon else None
self.idx_to_wrd = {}
checkpoint = torch.load(args.kenlm_model, map_location="cpu")
if "cfg" in checkpoint and checkpoint["cfg"] is not None:
lm_args = checkpoint["cfg"]
else:
lm_args = convert_namespace_to_omegaconf(checkpoint["args"])
with open_dict(lm_args.task):
lm_args.task.data = osp.dirname(args.kenlm_model)
task = tasks.setup_task(lm_args.task)
model = task.build_model(lm_args.model)
model.load_state_dict(checkpoint["model"], strict=False)
self.trie = Trie(self.vocab_size, self.silence)
self.word_dict = task.dictionary
self.unk_word = self.word_dict.unk()
self.lm = FairseqLM(self.word_dict, model)
if self.lexicon:
start_state = self.lm.start(False)
for i, (word, spellings) in enumerate(self.lexicon.items()):
if self.unit_lm:
word_idx = i
self.idx_to_wrd[i] = word
score = 0
else:
word_idx = self.word_dict.index(word)
_, score = self.lm.score(start_state, word_idx, no_cache=True)
for spelling in spellings:
spelling_idxs = [tgt_dict.index(token) for token in spelling]
assert (
tgt_dict.unk() not in spelling_idxs
), f"{spelling} {spelling_idxs}"
self.trie.insert(spelling_idxs, word_idx, score)
self.trie.smear(SmearingMode.MAX)
self.decoder_opts = LexiconDecoderOptions(
beam_size=args.beam,
beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
beam_threshold=args.beam_threshold,
lm_weight=args.lm_weight,
word_score=args.word_score,
unk_score=args.unk_weight,
sil_score=args.sil_weight,
log_add=False,
criterion_type=self.criterion_type,
)
self.decoder = LexiconDecoder(
self.decoder_opts,
self.trie,
self.lm,
self.silence,
self.blank,
self.unk_word,
[],
self.unit_lm,
)
else:
assert args.unit_lm, "lexicon free decoding can only be done with a unit language model"
from flashlight.lib.text.decoder import LexiconFreeDecoder, LexiconFreeDecoderOptions
d = {w: [[w]] for w in tgt_dict.symbols}
self.word_dict = create_word_dict(d)
self.lm = KenLM(args.kenlm_model, self.word_dict)
self.decoder_opts = LexiconFreeDecoderOptions(
beam_size=args.beam,
beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
beam_threshold=args.beam_threshold,
lm_weight=args.lm_weight,
sil_score=args.sil_weight,
log_add=False,
criterion_type=self.criterion_type,
)
self.decoder = LexiconFreeDecoder(
self.decoder_opts, self.lm, self.silence, self.blank, []
)
def decode(self, emissions):
B, T, N = emissions.size()
hypos = []
def idx_to_word(idx):
if self.unit_lm:
return self.idx_to_wrd[idx]
else:
return self.word_dict[idx]
def make_hypo(result):
hypo = {"tokens": self.get_tokens(result.tokens), "score": result.score}
if self.lexicon:
hypo["words"] = [idx_to_word(x) for x in result.words if x >= 0]
return hypo
for b in range(B):
emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
results = self.decoder.decode(emissions_ptr, T, N)
nbest_results = results[: self.nbest]
hypos.append([make_hypo(result) for result in nbest_results])
self.lm.empty_cache()
return hypos
class FairseqLMDecoder(BaseDecoder):
def __init__(self, cfg: DecoderConfig, tgt_dict: Dictionary) -> None:
super().__init__(cfg, tgt_dict)
self.lexicon = load_words(cfg.lexicon) if cfg.lexicon else None
self.idx_to_wrd = {}
checkpoint = torch.load(cfg.lmpath, map_location="cpu")
if "cfg" in checkpoint and checkpoint["cfg"] is not None:
lm_args = checkpoint["cfg"]
else:
lm_args = convert_namespace_to_omegaconf(checkpoint["args"])
with open_dict(lm_args.task):
lm_args.task.data = osp.dirname(cfg.lmpath)
task = tasks.setup_task(lm_args.task)
model = task.build_model(lm_args.model)
model.load_state_dict(checkpoint["model"], strict=False)
self.trie = Trie(self.vocab_size, self.silence)
self.word_dict = task.dictionary
self.unk_word = self.word_dict.unk()
self.lm = FairseqLM(self.word_dict, model)
if self.lexicon:
start_state = self.lm.start(False)
for i, (word, spellings) in enumerate(self.lexicon.items()):
if self.unitlm:
word_idx = i
self.idx_to_wrd[i] = word
score = 0
else:
word_idx = self.word_dict.index(word)
_, score = self.lm.score(start_state,
word_idx,
no_cache=True)
for spelling in spellings:
spelling_idxs = [
tgt_dict.index(token) for token in spelling
]
assert tgt_dict.unk() not in spelling_idxs, \
f"{spelling} {spelling_idxs}"
self.trie.insert(spelling_idxs, word_idx, score)
self.trie.smear(SmearingMode.MAX)
self.decoder_opts = LexiconDecoderOptions(
beam_size=cfg.beam,
beam_size_token=cfg.beamsizetoken or len(tgt_dict),
beam_threshold=cfg.beamthreshold,
lm_weight=cfg.lmweight,
word_score=cfg.wordscore,
unk_score=cfg.unkweight,
sil_score=cfg.silweight,
log_add=False,
criterion_type=self.criterion_type,
)
if self.asgtransitions is None:
self.asgtransitions = []
self.decoder = LexiconDecoder(
self.decoder_opts,
self.trie,
self.lm,
self.silence,
self.blank,
self.unk_word,
self.asgtransitions,
self.unitlm,
)
else:
assert self.unitlm, "Lexicon-free decoding requires unit LM"
d = {w: [[w]] for w in tgt_dict.symbols}
self.word_dict = create_word_dict(d)
self.lm = KenLM(cfg.lmpath, self.word_dict)
self.decoder_opts = LexiconFreeDecoderOptions(
beam_size=cfg.beam,
beam_size_token=cfg.beamsizetoken or len(tgt_dict),
beam_threshold=cfg.beamthreshold,
lm_weight=cfg.lmweight,
sil_score=cfg.silweight,
log_add=False,
criterion_type=self.criterion_type,
)
self.decoder = LexiconFreeDecoder(self.decoder_opts, self.lm,
self.silence, self.blank, [])
def decode(
self,
emissions: torch.FloatTensor,
) -> List[List[Dict[str, torch.LongTensor]]]:
B, T, N = emissions.size()
hypos = []
def make_hypo(result: DecodeResult) -> Dict[str, Any]:
hypo = {
"tokens": self.get_tokens(result.tokens),
"score": result.score,
}
if self.lexicon:
hypo["words"] = [
self.idx_to_wrd[x] if self.unitlm else self.word_dict[x]
for x in result.words if x >= 0
]
return hypo
for b in range(B):
emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
results = self.decoder.decode(emissions_ptr, T, N)
nbest_results = results[:self.nbest]
hypos.append([make_hypo(result) for result in nbest_results])
self.lm.empty_cache()
return hypos
