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# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
from dataclasses import dataclass, field
from fairseq.data.encoders import register_bpe
from fairseq.dataclass import FairseqDataclass
from fairseq import file_utils
@dataclass
class HuggingFaceByteLevelBPEConfig(FairseqDataclass):
bpe_merges: str = field(default="???", metadata={"help": "path to merges.txt"})
bpe_vocab: str = field(default="???", metadata={"help": "path to vocab.json"})
bpe_add_prefix_space: bool = field(
default=False, metadata={"help": "add prefix space before encoding"}
)
@register_bpe("hf_byte_bpe", dataclass=HuggingFaceByteLevelBPEConfig)
class HuggingFaceByteLevelBPE(object):
def __init__(self, cfg):
try:
from tokenizers import ByteLevelBPETokenizer
except ImportError:
raise ImportError(
"Please install huggingface/tokenizers with: " "pip install tokenizers"
)
bpe_vocab = file_utils.cached_path(cfg.bpe_vocab)
bpe_merges = file_utils.cached_path(cfg.bpe_merges)
self.bpe = ByteLevelBPETokenizer(
bpe_vocab,
bpe_merges,
add_prefix_space=cfg.bpe_add_prefix_space,
)
def encode(self, x: str) -> str:
return " ".join(map(str, self.bpe.encode(x).ids))
def decode(self, x: str) -> str:
return self.bpe.decode(
[int(tok) if tok not in {"<unk>", "<mask>"} else tok for tok in x.split()]
)
def is_beginning_of_word(self, x: str) -> bool:
return self.decode(x).startswith(" ")
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