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540 lines
24 KiB
540 lines
24 KiB
2 years ago
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# coding=utf-8
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# Copyright 2018 The Google AI Language Team Authors and The HuggingFace Inc. team.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Tokenization classes for Bert."""
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import collections
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import os
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import unicodedata
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from typing import List, Optional, Tuple
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from transformers.tokenization_utils import PreTrainedTokenizer, _is_control, _is_punctuation, _is_whitespace
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from transformers.utils import logging
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logger = logging.get_logger(__name__)
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VOCAB_FILES_NAMES = {"vocab_file": "vocab.txt"}
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PRETRAINED_VOCAB_FILES_MAP = {
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"vocab_file": {
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"bert-base-uncased": "https://huggingface.co/bert-base-uncased/resolve/main/vocab.txt",
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"bert-large-uncased": "https://huggingface.co/bert-large-uncased/resolve/main/vocab.txt",
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"bert-base-cased": "https://huggingface.co/bert-base-cased/resolve/main/vocab.txt",
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"bert-large-cased": "https://huggingface.co/bert-large-cased/resolve/main/vocab.txt",
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"bert-base-multilingual-uncased": "https://huggingface.co/bert-base-multilingual-uncased/resolve/main/vocab.txt",
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"bert-base-multilingual-cased": "https://huggingface.co/bert-base-multilingual-cased/resolve/main/vocab.txt",
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"bert-base-chinese": "https://huggingface.co/bert-base-chinese/resolve/main/vocab.txt",
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"bert-base-german-cased": "https://huggingface.co/bert-base-german-cased/resolve/main/vocab.txt",
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"bert-large-uncased-whole-word-masking": "https://huggingface.co/bert-large-uncased-whole-word-masking/resolve/main/vocab.txt",
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"bert-large-cased-whole-word-masking": "https://huggingface.co/bert-large-cased-whole-word-masking/resolve/main/vocab.txt",
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"bert-large-uncased-whole-word-masking-finetuned-squad": "https://huggingface.co/bert-large-uncased-whole-word-masking-finetuned-squad/resolve/main/vocab.txt",
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"bert-large-cased-whole-word-masking-finetuned-squad": "https://huggingface.co/bert-large-cased-whole-word-masking-finetuned-squad/resolve/main/vocab.txt",
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"bert-base-cased-finetuned-mrpc": "https://huggingface.co/bert-base-cased-finetuned-mrpc/resolve/main/vocab.txt",
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"bert-base-german-dbmdz-cased": "https://huggingface.co/bert-base-german-dbmdz-cased/resolve/main/vocab.txt",
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"bert-base-german-dbmdz-uncased": "https://huggingface.co/bert-base-german-dbmdz-uncased/resolve/main/vocab.txt",
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"TurkuNLP/bert-base-finnish-cased-v1": "https://huggingface.co/TurkuNLP/bert-base-finnish-cased-v1/resolve/main/vocab.txt",
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"TurkuNLP/bert-base-finnish-uncased-v1": "https://huggingface.co/TurkuNLP/bert-base-finnish-uncased-v1/resolve/main/vocab.txt",
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"wietsedv/bert-base-dutch-cased": "https://huggingface.co/wietsedv/bert-base-dutch-cased/resolve/main/vocab.txt",
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}
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}
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PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
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"bert-base-uncased": 512,
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"bert-large-uncased": 512,
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"bert-base-cased": 512,
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"bert-large-cased": 512,
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"bert-base-multilingual-uncased": 512,
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"bert-base-multilingual-cased": 512,
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"bert-base-chinese": 512,
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"bert-base-german-cased": 512,
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"bert-large-uncased-whole-word-masking": 512,
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"bert-large-cased-whole-word-masking": 512,
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"bert-large-uncased-whole-word-masking-finetuned-squad": 512,
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"bert-large-cased-whole-word-masking-finetuned-squad": 512,
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"bert-base-cased-finetuned-mrpc": 512,
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"bert-base-german-dbmdz-cased": 512,
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"bert-base-german-dbmdz-uncased": 512,
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"TurkuNLP/bert-base-finnish-cased-v1": 512,
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"TurkuNLP/bert-base-finnish-uncased-v1": 512,
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"wietsedv/bert-base-dutch-cased": 512,
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}
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PRETRAINED_INIT_CONFIGURATION = {
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"bert-base-uncased": {"do_lower_case": True},
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"bert-large-uncased": {"do_lower_case": True},
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"bert-base-cased": {"do_lower_case": False},
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"bert-large-cased": {"do_lower_case": False},
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"bert-base-multilingual-uncased": {"do_lower_case": True},
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"bert-base-multilingual-cased": {"do_lower_case": False},
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"bert-base-chinese": {"do_lower_case": False},
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"bert-base-german-cased": {"do_lower_case": False},
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"bert-large-uncased-whole-word-masking": {"do_lower_case": True},
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"bert-large-cased-whole-word-masking": {"do_lower_case": False},
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"bert-large-uncased-whole-word-masking-finetuned-squad": {"do_lower_case": True},
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"bert-large-cased-whole-word-masking-finetuned-squad": {"do_lower_case": False},
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"bert-base-cased-finetuned-mrpc": {"do_lower_case": False},
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"bert-base-german-dbmdz-cased": {"do_lower_case": False},
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"bert-base-german-dbmdz-uncased": {"do_lower_case": True},
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"TurkuNLP/bert-base-finnish-cased-v1": {"do_lower_case": False},
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"TurkuNLP/bert-base-finnish-uncased-v1": {"do_lower_case": True},
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"wietsedv/bert-base-dutch-cased": {"do_lower_case": False},
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}
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def load_vocab(vocab_file):
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"""Loads a vocabulary file into a dictionary."""
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vocab = collections.OrderedDict()
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with open(vocab_file, "r", encoding="utf-8") as reader:
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tokens = reader.readlines()
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for index, token in enumerate(tokens):
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token = token.rstrip("\n")
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vocab[token] = index
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return vocab
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def whitespace_tokenize(text):
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"""Runs basic whitespace cleaning and splitting on a piece of text."""
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text = text.strip()
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if not text:
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return []
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tokens = text.split()
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return tokens
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class BertTokenizer(PreTrainedTokenizer):
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r"""
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Construct a BERT tokenizer. Based on WordPiece.
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This tokenizer inherits from :class:`~transformers.PreTrainedTokenizer` which contains most of the main methods.
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Users should refer to this superclass for more information regarding those methods.
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Args:
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vocab_file (:obj:`str`):
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File containing the vocabulary.
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do_lower_case (:obj:`bool`, `optional`, defaults to :obj:`True`):
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Whether or not to lowercase the input when tokenizing.
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do_basic_tokenize (:obj:`bool`, `optional`, defaults to :obj:`True`):
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Whether or not to do basic tokenization before WordPiece.
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never_split (:obj:`Iterable`, `optional`):
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Collection of tokens which will never be split during tokenization. Only has an effect when
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:obj:`do_basic_tokenize=True`
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unk_token (:obj:`str`, `optional`, defaults to :obj:`"[UNK]"`):
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The unknown token. A token that is not in the vocabulary cannot be converted to an ID and is set to be this
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token instead.
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sep_token (:obj:`str`, `optional`, defaults to :obj:`"[SEP]"`):
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The separator token, which is used when building a sequence from multiple sequences, e.g. two sequences for
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sequence classification or for a text and a question for question answering. It is also used as the last
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token of a sequence built with special tokens.
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pad_token (:obj:`str`, `optional`, defaults to :obj:`"[PAD]"`):
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The token used for padding, for example when batching sequences of different lengths.
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cls_token (:obj:`str`, `optional`, defaults to :obj:`"[CLS]"`):
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The classifier token which is used when doing sequence classification (classification of the whole sequence
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instead of per-token classification). It is the first token of the sequence when built with special tokens.
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mask_token (:obj:`str`, `optional`, defaults to :obj:`"[MASK]"`):
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The token used for masking values. This is the token used when training this model with masked language
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modeling. This is the token which the model will try to predict.
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tokenize_chinese_chars (:obj:`bool`, `optional`, defaults to :obj:`True`):
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Whether or not to tokenize Chinese characters.
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This should likely be deactivated for Japanese (see this `issue
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<https://github.com/huggingface/transformers/issues/328>`__).
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strip_accents: (:obj:`bool`, `optional`):
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Whether or not to strip all accents. If this option is not specified, then it will be determined by the
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value for :obj:`lowercase` (as in the original BERT).
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"""
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vocab_files_names = VOCAB_FILES_NAMES
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pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
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pretrained_init_configuration = PRETRAINED_INIT_CONFIGURATION
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max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
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def __init__(
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self,
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vocab_file,
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do_lower_case=True,
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do_basic_tokenize=True,
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never_split=None,
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unk_token="[UNK]",
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sep_token="[SEP]",
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pad_token="[PAD]",
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cls_token="[CLS]",
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mask_token="[MASK]",
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tokenize_chinese_chars=True,
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strip_accents=None,
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**kwargs
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):
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super().__init__(
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do_lower_case=do_lower_case,
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do_basic_tokenize=do_basic_tokenize,
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never_split=never_split,
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unk_token=unk_token,
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sep_token=sep_token,
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pad_token=pad_token,
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cls_token=cls_token,
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mask_token=mask_token,
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tokenize_chinese_chars=tokenize_chinese_chars,
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strip_accents=strip_accents,
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**kwargs,
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)
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if not os.path.isfile(vocab_file):
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raise ValueError(
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"Can't find a vocabulary file at path '{}'. To load the vocabulary from a Google pretrained "
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"model use `tokenizer = BertTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`".format(vocab_file)
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)
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self.vocab = load_vocab(vocab_file)
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self.ids_to_tokens = collections.OrderedDict([(ids, tok) for tok, ids in self.vocab.items()])
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self.do_basic_tokenize = do_basic_tokenize
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if do_basic_tokenize:
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self.basic_tokenizer = BasicTokenizer(
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do_lower_case=do_lower_case,
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never_split=never_split,
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tokenize_chinese_chars=tokenize_chinese_chars,
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strip_accents=strip_accents,
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)
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self.wordpiece_tokenizer = WordpieceTokenizer(vocab=self.vocab, unk_token=self.unk_token)
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@property
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def do_lower_case(self):
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return self.basic_tokenizer.do_lower_case
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@property
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def vocab_size(self):
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return len(self.vocab)
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def get_vocab(self):
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return dict(self.vocab, **self.added_tokens_encoder)
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def _tokenize(self, text):
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split_tokens = []
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if self.do_basic_tokenize:
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for token in self.basic_tokenizer.tokenize(text, never_split=self.all_special_tokens):
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# If the token is part of the never_split set
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if token in self.basic_tokenizer.never_split:
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split_tokens.append(token)
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else:
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split_tokens += self.wordpiece_tokenizer.tokenize(token)
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else:
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split_tokens = self.wordpiece_tokenizer.tokenize(text)
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return split_tokens
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def _convert_token_to_id(self, token):
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""" Converts a token (str) in an id using the vocab. """
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return self.vocab.get(token, self.vocab.get(self.unk_token))
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def _convert_id_to_token(self, index):
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"""Converts an index (integer) in a token (str) using the vocab."""
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return self.ids_to_tokens.get(index, self.unk_token)
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def convert_tokens_to_string(self, tokens):
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""" Converts a sequence of tokens (string) in a single string. """
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out_string = " ".join(tokens).replace(" ##", "").strip()
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return out_string
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def build_inputs_with_special_tokens(
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self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None
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) -> List[int]:
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"""
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Build model inputs from a sequence or a pair of sequence for sequence classification tasks by concatenating and
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adding special tokens. A BERT sequence has the following format:
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- single sequence: ``[CLS] X ``
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- pair of sequences: ``[CLS] A [SEP] B [SEP]``
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Args:
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token_ids_0 (:obj:`List[int]`):
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List of IDs to which the special tokens will be added.
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token_ids_1 (:obj:`List[int]`, `optional`):
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Optional second list of IDs for sequence pairs.
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Returns:
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:obj:`List[int]`: List of `input IDs <../glossary.html#input-ids>`__ with the appropriate special tokens.
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"""
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if token_ids_1 is None:
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return [self.cls_token_id] + token_ids_0
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cls = [self.cls_token_id]
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sep = [self.sep_token_id]
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return cls + token_ids_0 + sep + token_ids_1 + sep
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def get_special_tokens_mask(
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self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None, already_has_special_tokens: bool = False
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) -> List[int]:
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"""
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Retrieve sequence ids from a token list that has no special tokens added. This method is called when adding
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special tokens using the tokenizer ``prepare_for_model`` method.
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Args:
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token_ids_0 (:obj:`List[int]`):
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List of IDs.
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token_ids_1 (:obj:`List[int]`, `optional`):
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Optional second list of IDs for sequence pairs.
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already_has_special_tokens (:obj:`bool`, `optional`, defaults to :obj:`False`):
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Whether or not the token list is already formatted with special tokens for the model.
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Returns:
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:obj:`List[int]`: A list of integers in the range [0, 1]: 1 for a special token, 0 for a sequence token.
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"""
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if already_has_special_tokens:
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if token_ids_1 is not None:
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raise ValueError(
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"You should not supply a second sequence if the provided sequence of "
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"ids is already formatted with special tokens for the model."
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)
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return list(map(lambda x: 1 if x in [self.sep_token_id, self.cls_token_id] else 0, token_ids_0))
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if token_ids_1 is not None:
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return [1] + ([0] * len(token_ids_0)) + [1] + ([0] * len(token_ids_1)) + [1]
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return [1] + ([0] * len(token_ids_0))
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def create_token_type_ids_from_sequences(
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self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None
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) -> List[int]:
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"""
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Create a mask from the two sequences passed to be used in a sequence-pair classification task. A BERT sequence
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pair mask has the following format:
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::
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0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1
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| first sequence | second sequence |
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If :obj:`token_ids_1` is :obj:`None`, this method only returns the first portion of the mask (0s).
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Args:
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token_ids_0 (:obj:`List[int]`):
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List of IDs.
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token_ids_1 (:obj:`List[int]`, `optional`):
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Optional second list of IDs for sequence pairs.
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Returns:
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:obj:`List[int]`: List of `token type IDs <../glossary.html#token-type-ids>`_ according to the given
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sequence(s).
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"""
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sep = [self.sep_token_id]
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cls = [self.cls_token_id]
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if token_ids_1 is None:
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return len(cls + token_ids_0 + sep) * [0]
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return len(cls + token_ids_0 + sep) * [0] + len(token_ids_1 + sep) * [1]
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def save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]:
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index = 0
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if os.path.isdir(save_directory):
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vocab_file = os.path.join(
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save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["vocab_file"]
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)
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else:
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vocab_file = (filename_prefix + "-" if filename_prefix else "") + save_directory
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with open(vocab_file, "w", encoding="utf-8") as writer:
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for token, token_index in sorted(self.vocab.items(), key=lambda kv: kv[1]):
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if index != token_index:
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logger.warning(
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"Saving vocabulary to {}: vocabulary indices are not consecutive."
|
||
|
" Please check that the vocabulary is not corrupted!".format(vocab_file)
|
||
|
)
|
||
|
index = token_index
|
||
|
writer.write(token + "\n")
|
||
|
index += 1
|
||
|
return (vocab_file,)
|
||
|
|
||
|
|
||
|
class BasicTokenizer(object):
|
||
|
"""
|
||
|
Constructs a BasicTokenizer that will run basic tokenization (punctuation splitting, lower casing, etc.).
|
||
|
Args:
|
||
|
do_lower_case (:obj:`bool`, `optional`, defaults to :obj:`True`):
|
||
|
Whether or not to lowercase the input when tokenizing.
|
||
|
never_split (:obj:`Iterable`, `optional`):
|
||
|
Collection of tokens which will never be split during tokenization. Only has an effect when
|
||
|
:obj:`do_basic_tokenize=True`
|
||
|
tokenize_chinese_chars (:obj:`bool`, `optional`, defaults to :obj:`True`):
|
||
|
Whether or not to tokenize Chinese characters.
|
||
|
This should likely be deactivated for Japanese (see this `issue
|
||
|
<https://github.com/huggingface/transformers/issues/328>`__).
|
||
|
strip_accents: (:obj:`bool`, `optional`):
|
||
|
Whether or not to strip all accents. If this option is not specified, then it will be determined by the
|
||
|
value for :obj:`lowercase` (as in the original BERT).
|
||
|
"""
|
||
|
|
||
|
def __init__(self, do_lower_case=True, never_split=None, tokenize_chinese_chars=True, strip_accents=None):
|
||
|
if never_split is None:
|
||
|
never_split = []
|
||
|
self.do_lower_case = do_lower_case
|
||
|
self.never_split = set(never_split)
|
||
|
self.tokenize_chinese_chars = tokenize_chinese_chars
|
||
|
self.strip_accents = strip_accents
|
||
|
|
||
|
def tokenize(self, text, never_split=None):
|
||
|
"""
|
||
|
Basic Tokenization of a piece of text. Split on "white spaces" only, for sub-word tokenization, see
|
||
|
WordPieceTokenizer.
|
||
|
Args:
|
||
|
**never_split**: (`optional`) list of str
|
||
|
Kept for backward compatibility purposes. Now implemented directly at the base class level (see
|
||
|
:func:`PreTrainedTokenizer.tokenize`) List of token not to split.
|
||
|
"""
|
||
|
# union() returns a new set by concatenating the two sets.
|
||
|
never_split = self.never_split.union(set(never_split)) if never_split else self.never_split
|
||
|
text = self._clean_text(text)
|
||
|
|
||
|
# This was added on November 1st, 2018 for the multilingual and Chinese
|
||
|
# models. This is also applied to the English models now, but it doesn't
|
||
|
# matter since the English models were not trained on any Chinese data
|
||
|
# and generally don't have any Chinese data in them (there are Chinese
|
||
|
# characters in the vocabulary because Wikipedia does have some Chinese
|
||
|
# words in the English Wikipedia.).
|
||
|
if self.tokenize_chinese_chars:
|
||
|
text = self._tokenize_chinese_chars(text)
|
||
|
orig_tokens = whitespace_tokenize(text)
|
||
|
split_tokens = []
|
||
|
for token in orig_tokens:
|
||
|
if token not in never_split:
|
||
|
if self.do_lower_case:
|
||
|
token = token.lower()
|
||
|
if self.strip_accents is not False:
|
||
|
token = self._run_strip_accents(token)
|
||
|
elif self.strip_accents:
|
||
|
token = self._run_strip_accents(token)
|
||
|
split_tokens.extend(self._run_split_on_punc(token, never_split))
|
||
|
|
||
|
output_tokens = whitespace_tokenize(" ".join(split_tokens))
|
||
|
return output_tokens
|
||
|
|
||
|
def _run_strip_accents(self, text):
|
||
|
"""Strips accents from a piece of text."""
|
||
|
text = unicodedata.normalize("NFD", text)
|
||
|
output = []
|
||
|
for char in text:
|
||
|
cat = unicodedata.category(char)
|
||
|
if cat == "Mn":
|
||
|
continue
|
||
|
output.append(char)
|
||
|
return "".join(output)
|
||
|
|
||
|
def _run_split_on_punc(self, text, never_split=None):
|
||
|
"""Splits punctuation on a piece of text."""
|
||
|
if never_split is not None and text in never_split:
|
||
|
return [text]
|
||
|
chars = list(text)
|
||
|
i = 0
|
||
|
start_new_word = True
|
||
|
output = []
|
||
|
while i < len(chars):
|
||
|
char = chars[i]
|
||
|
if _is_punctuation(char):
|
||
|
output.append([char])
|
||
|
start_new_word = True
|
||
|
else:
|
||
|
if start_new_word:
|
||
|
output.append([])
|
||
|
start_new_word = False
|
||
|
output[-1].append(char)
|
||
|
i += 1
|
||
|
|
||
|
return ["".join(x) for x in output]
|
||
|
|
||
|
def _tokenize_chinese_chars(self, text):
|
||
|
"""Adds whitespace around any CJK character."""
|
||
|
output = []
|
||
|
for char in text:
|
||
|
cp = ord(char)
|
||
|
if self._is_chinese_char(cp):
|
||
|
output.append(" ")
|
||
|
output.append(char)
|
||
|
output.append(" ")
|
||
|
else:
|
||
|
output.append(char)
|
||
|
return "".join(output)
|
||
|
|
||
|
def _is_chinese_char(self, cp):
|
||
|
"""Checks whether CP is the codepoint of a CJK character."""
|
||
|
# This defines a "chinese character" as anything in the CJK Unicode block:
|
||
|
# https://en.wikipedia.org/wiki/CJK_Unified_Ideographs_(Unicode_block)
|
||
|
#
|
||
|
# Note that the CJK Unicode block is NOT all Japanese and Korean characters,
|
||
|
# despite its name. The modern Korean Hangul alphabet is a different block,
|
||
|
# as is Japanese Hiragana and Katakana. Those alphabets are used to write
|
||
|
# space-separated words, so they are not treated specially and handled
|
||
|
# like the all of the other languages.
|
||
|
if (
|
||
|
(cp >= 0x4E00 and cp <= 0x9FFF)
|
||
|
or (cp >= 0x3400 and cp <= 0x4DBF) #
|
||
|
or (cp >= 0x20000 and cp <= 0x2A6DF) #
|
||
|
or (cp >= 0x2A700 and cp <= 0x2B73F) #
|
||
|
or (cp >= 0x2B740 and cp <= 0x2B81F) #
|
||
|
or (cp >= 0x2B820 and cp <= 0x2CEAF) #
|
||
|
or (cp >= 0xF900 and cp <= 0xFAFF)
|
||
|
or (cp >= 0x2F800 and cp <= 0x2FA1F) #
|
||
|
): #
|
||
|
return True
|
||
|
|
||
|
return False
|
||
|
|
||
|
def _clean_text(self, text):
|
||
|
"""Performs invalid character removal and whitespace cleanup on text."""
|
||
|
output = []
|
||
|
for char in text:
|
||
|
cp = ord(char)
|
||
|
if cp == 0 or cp == 0xFFFD or _is_control(char):
|
||
|
continue
|
||
|
if _is_whitespace(char):
|
||
|
output.append(" ")
|
||
|
else:
|
||
|
output.append(char)
|
||
|
return "".join(output)
|
||
|
|
||
|
|
||
|
class WordpieceTokenizer(object):
|
||
|
"""Runs WordPiece tokenization."""
|
||
|
|
||
|
def __init__(self, vocab, unk_token, max_input_chars_per_word=100):
|
||
|
self.vocab = vocab
|
||
|
self.unk_token = unk_token
|
||
|
self.max_input_chars_per_word = max_input_chars_per_word
|
||
|
|
||
|
def tokenize(self, text):
|
||
|
"""
|
||
|
Tokenizes a piece of text into its word pieces. This uses a greedy longest-match-first algorithm to perform
|
||
|
tokenization using the given vocabulary.
|
||
|
For example, :obj:`input = "unaffable"` wil return as output :obj:`["un", "##aff", "##able"]`.
|
||
|
Args:
|
||
|
text: A single token or whitespace separated tokens. This should have
|
||
|
already been passed through `BasicTokenizer`.
|
||
|
Returns:
|
||
|
A list of wordpiece tokens.
|
||
|
"""
|
||
|
|
||
|
output_tokens = []
|
||
|
for token in whitespace_tokenize(text):
|
||
|
chars = list(token)
|
||
|
if len(chars) > self.max_input_chars_per_word:
|
||
|
output_tokens.append(self.unk_token)
|
||
|
continue
|
||
|
|
||
|
is_bad = False
|
||
|
start = 0
|
||
|
sub_tokens = []
|
||
|
while start < len(chars):
|
||
|
end = len(chars)
|
||
|
cur_substr = None
|
||
|
while start < end:
|
||
|
substr = "".join(chars[start:end])
|
||
|
if start > 0:
|
||
|
substr = "##" + substr
|
||
|
if substr in self.vocab:
|
||
|
cur_substr = substr
|
||
|
break
|
||
|
end -= 1
|
||
|
if cur_substr is None:
|
||
|
is_bad = True
|
||
|
break
|
||
|
sub_tokens.append(cur_substr)
|
||
|
start = end
|
||
|
|
||
|
if is_bad:
|
||
|
output_tokens.append(self.unk_token)
|
||
|
else:
|
||
|
output_tokens.extend(sub_tokens)
|
||
|
return output_tokens
|