# coding=utf-8
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""" Tokenization class for model BertGeneration."""
import os
from shutil import copyfile
from typing import List
from .tokenization_utils import PreTrainedTokenizer
from .utils import logging
logger = logging.get_logger(__name__)
VOCAB_FILES_NAMES = {"vocab_file": "spiece.model"}
tokenizer_url = (
"https://s3.amazonaws.com/models.huggingface.co/bert/google/bert_for_seq_generation_L-24_bbc_encoder/spiece.model"
)
[docs]class BertGenerationTokenizer(PreTrainedTokenizer):
"""
Constructs a BertGenerationTokenizer tokenizer. Based on `SentencePiece <https://github.com/google/sentencepiece>`__ .
This tokenizer inherits from :class:`~transformers.PreTrainedTokenizer` which contains most of the methods. Users
should refer to the superclass for more information regarding methods.
Args:
vocab_file (:obj:`string`):
`SentencePiece <https://github.com/google/sentencepiece>`__ file (generally has a `.spm` extension) that
contains the vocabulary necessary to instantiate a tokenizer.
eos_token (:obj:`string`, `optional`, defaults to :obj:`"</s>"`):
The end of sequence token.
bos_token (:obj:`string`, `optional`, defaults to :obj:`"<s>"`):
The begin of sequence token.
unk_token (:obj:`string`, `optional`, defaults to :obj:`"<unk>"`):
The unknown token. A token that is not in the vocabulary cannot be converted to an ID and is set to be this
token instead.
pad_token (:obj:`string`, `optional`, defaults to :obj:`"<pad>"`):
The token used for padding, for example when batching sequences of different lengths.
"""
vocab_files_names = VOCAB_FILES_NAMES
prefix_tokens: List[int] = []
def __init__(
self,
vocab_file,
bos_token="<s>",
eos_token="</s>",
unk_token="<unk>",
pad_token="<pad>",
sep_token="<::::>",
**kwargs
):
# Add extra_ids to the special token list
super().__init__(
bos_token=bos_token,
eos_token=eos_token,
unk_token=unk_token,
pad_token=pad_token,
sep_token=sep_token,
**kwargs,
)
try:
import sentencepiece as spm
except ImportError:
logger.warning(
"You need to install SentencePiece to use T5Tokenizer:"
"https://github.com/google/sentencepiece"
"pip install sentencepiece"
)
raise
self.vocab_file = vocab_file
self.sp_model = spm.SentencePieceProcessor()
self.sp_model.Load(vocab_file)
@property
def vocab_size(self):
return self.sp_model.get_piece_size()
[docs] def get_vocab(self):
vocab = {self.convert_ids_to_tokens(i): i for i in range(self.vocab_size)}
vocab.update(self.added_tokens_encoder)
return vocab
def __getstate__(self):
state = self.__dict__.copy()
state["sp_model"] = None
return state
def __setstate__(self, d):
self.__dict__ = d
try:
import sentencepiece as spm
except ImportError:
logger.warning(
"You need to install SentencePiece to use BertGenerationTokenizer: https://github.com/google/sentencepiece"
"pip install sentencepiece"
)
raise
self.sp_model = spm.SentencePieceProcessor()
self.sp_model.Load(self.vocab_file)
def _tokenize(self, text, sample=False):
"""Take as input a string and return a list of strings (tokens) for words/sub-words"""
if not sample:
pieces = self.sp_model.EncodeAsPieces(text)
else:
pieces = self.sp_model.SampleEncodeAsPieces(text, 64, 0.1)
return pieces
def _convert_token_to_id(self, token):
""" Converts a token (str) in an id using the vocab. """
return self.sp_model.piece_to_id(token)
def _convert_id_to_token(self, index):
"""Converts an index (integer) in a token (str) using the vocab."""
token = self.sp_model.IdToPiece(index)
return token
[docs] def convert_tokens_to_string(self, tokens):
""" Converts a sequence of tokens (string) in a single string. """
out_string = self.sp_model.decode_pieces(tokens)
return out_string
[docs] def save_vocabulary(self, save_directory):
"""Save the sentencepiece vocabulary (copy original file) and special tokens file
to a directory.
"""
if not os.path.isdir(save_directory):
logger.error("Vocabulary path ({}) should be a directory".format(save_directory))
return
out_vocab_file = os.path.join(save_directory, VOCAB_FILES_NAMES["vocab_file"])
if os.path.abspath(self.vocab_file) != os.path.abspath(out_vocab_file):
copyfile(self.vocab_file, out_vocab_file)
return (out_vocab_file,)