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# coding=utf-8 | |
# Copyright 2021 The Facebook Inc. and The HuggingFace Inc. team. All rights reserved. | |
# | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
"""Fast Tokenization class for Blenderbot.""" | |
import json | |
from typing import List, Optional, Tuple | |
from tokenizers import pre_tokenizers, processors | |
from ...tokenization_utils_base import AddedToken, BatchEncoding | |
from ...tokenization_utils_fast import PreTrainedTokenizerFast | |
from ...utils import logging | |
from .tokenization_blenderbot import BlenderbotTokenizer | |
logger = logging.get_logger(__name__) | |
VOCAB_FILES_NAMES = { | |
"vocab_file": "vocab.json", | |
"merges_file": "merges.txt", | |
"tokenizer_config_file": "tokenizer_config.json", | |
} | |
PRETRAINED_VOCAB_FILES_MAP = { | |
"vocab_file": {"facebook/blenderbot-3B": "https://huggingface.co/facebook/blenderbot-3B/resolve/main/vocab.json"}, | |
"merges_file": {"facebook/blenderbot-3B": "https://huggingface.co/facebook/blenderbot-3B/resolve/main/merges.txt"}, | |
"tokenizer_config_file": { | |
"facebook/blenderbot-3B": "https://huggingface.co/facebook/blenderbot-3B/resolve/main/tokenizer_config.json" | |
}, | |
} | |
PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {"facebook/blenderbot-3B": 128} | |
class BlenderbotTokenizerFast(PreTrainedTokenizerFast): | |
""" | |
Construct a "fast" Blenderbot tokenizer (backed by HuggingFace's *tokenizers* library), derived from the GPT-2 | |
tokenizer, using byte-level Byte-Pair-Encoding. | |
This tokenizer has been trained to treat spaces like parts of the tokens (a bit like sentencepiece) so a word will | |
be encoded differently whether it is at the beginning of the sentence (without space) or not: | |
```python | |
>>> from transformers import BlenderbotTokenizerFast | |
>>> tokenizer = BlenderbotTokenizerFast.from_pretrained("facebook/blenderbot-3B") | |
>>> tokenizer("Hello world")["input_ids"] | |
[6950, 1085, 2] | |
>>> tokenizer(" Hello world")["input_ids"] | |
[6950, 1085, 2] | |
``` | |
You can get around that behavior by passing `add_prefix_space=True` when instantiating this tokenizer or when you | |
call it on some text, but since the model was not pretrained this way, it might yield a decrease in performance. | |
<Tip> | |
When used with `is_split_into_words=True`, this tokenizer needs to be instantiated with `add_prefix_space=True`. | |
</Tip> | |
This tokenizer inherits from [`PreTrainedTokenizerFast`] which contains most of the main methods. Users should | |
refer to this superclass for more information regarding those methods. | |
Args: | |
vocab_file (`str`): | |
Path to the vocabulary file. | |
merges_file (`str`): | |
Path to the merges file. | |
errors (`str`, *optional*, defaults to `"replace"`): | |
Paradigm to follow when decoding bytes to UTF-8. See | |
[bytes.decode](https://docs.python.org/3/library/stdtypes.html#bytes.decode) for more information. | |
bos_token (`str`, *optional*, defaults to `"<s>"`): | |
The beginning of sequence token that was used during pretraining. Can be used a sequence classifier token. | |
<Tip> | |
When building a sequence using special tokens, this is not the token that is used for the beginning of | |
sequence. The token used is the `cls_token`. | |
</Tip> | |
eos_token (`str`, *optional*, defaults to `"</s>"`): | |
The end of sequence token. | |
<Tip> | |
When building a sequence using special tokens, this is not the token that is used for the end of sequence. | |
The token used is the `sep_token`. | |
</Tip> | |
sep_token (`str`, *optional*, defaults to `"</s>"`): | |
The separator token, which is used when building a sequence from multiple sequences, e.g. two sequences for | |
sequence classification or for a text and a question for question answering. It is also used as the last | |
token of a sequence built with special tokens. | |
cls_token (`str`, *optional*, defaults to `"<s>"`): | |
The classifier token which is used when doing sequence classification (classification of the whole sequence | |
instead of per-token classification). It is the first token of the sequence when built with special tokens. | |
unk_token (`str`, *optional*, defaults to `"<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 (`str`, *optional*, defaults to `"<pad>"`): | |
The token used for padding, for example when batching sequences of different lengths. | |
mask_token (`str`, *optional*, defaults to `"<mask>"`): | |
The token used for masking values. This is the token used when training this model with masked language | |
modeling. This is the token which the model will try to predict. | |
add_prefix_space (`bool`, *optional*, defaults to `False`): | |
Whether or not to add an initial space to the input. This allows to treat the leading word just as any | |
other word. (Blenderbot tokenizer detect beginning of words by the preceding space). | |
trim_offsets (`bool`, *optional*, defaults to `True`): | |
Whether the post processing step should trim offsets to avoid including whitespaces. | |
""" | |
vocab_files_names = VOCAB_FILES_NAMES | |
pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP | |
max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES | |
model_input_names = ["input_ids", "attention_mask"] | |
slow_tokenizer_class = BlenderbotTokenizer | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast.__init__ with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def __init__( | |
self, | |
vocab_file=None, | |
merges_file=None, | |
tokenizer_file=None, | |
errors="replace", | |
bos_token="<s>", | |
eos_token="</s>", | |
sep_token="</s>", | |
cls_token="<s>", | |
unk_token="<unk>", | |
pad_token="<pad>", | |
mask_token="<mask>", | |
add_prefix_space=False, | |
trim_offsets=True, | |
**kwargs, | |
): | |
mask_token = ( | |
AddedToken(mask_token, lstrip=True, rstrip=False, normalized=False) | |
if isinstance(mask_token, str) | |
else mask_token | |
) | |
super().__init__( | |
vocab_file, | |
merges_file, | |
tokenizer_file=tokenizer_file, | |
errors=errors, | |
bos_token=bos_token, | |
eos_token=eos_token, | |
sep_token=sep_token, | |
cls_token=cls_token, | |
unk_token=unk_token, | |
pad_token=pad_token, | |
mask_token=mask_token, | |
add_prefix_space=add_prefix_space, | |
trim_offsets=trim_offsets, | |
**kwargs, | |
) | |
pre_tok_state = json.loads(self.backend_tokenizer.pre_tokenizer.__getstate__()) | |
if pre_tok_state.get("add_prefix_space", add_prefix_space) != add_prefix_space: | |
pre_tok_class = getattr(pre_tokenizers, pre_tok_state.pop("type")) | |
pre_tok_state["add_prefix_space"] = add_prefix_space | |
self.backend_tokenizer.pre_tokenizer = pre_tok_class(**pre_tok_state) | |
self.add_prefix_space = add_prefix_space | |
tokenizer_component = "post_processor" | |
tokenizer_component_instance = getattr(self.backend_tokenizer, tokenizer_component, None) | |
if tokenizer_component_instance: | |
state = json.loads(tokenizer_component_instance.__getstate__()) | |
# The lists 'sep' and 'cls' must be cased in tuples for the object `post_processor_class` | |
if "sep" in state: | |
state["sep"] = tuple(state["sep"]) | |
if "cls" in state: | |
state["cls"] = tuple(state["cls"]) | |
changes_to_apply = False | |
if state.get("add_prefix_space", add_prefix_space) != add_prefix_space: | |
state["add_prefix_space"] = add_prefix_space | |
changes_to_apply = True | |
if state.get("trim_offsets", trim_offsets) != trim_offsets: | |
state["trim_offsets"] = trim_offsets | |
changes_to_apply = True | |
if changes_to_apply: | |
component_class = getattr(processors, state.pop("type")) | |
new_value = component_class(**state) | |
setattr(self.backend_tokenizer, tokenizer_component, new_value) | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast.mask_token with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def mask_token(self) -> str: | |
""" | |
`str`: Mask token, to use when training a model with masked-language modeling. Log an error if used while not | |
having been set. | |
Blenderbot tokenizer has a special mask token to be usable in the fill-mask pipeline. The mask token will | |
greedily comprise the space before the *<mask>*. | |
""" | |
if self._mask_token is None: | |
if self.verbose: | |
logger.error("Using mask_token, but it is not set yet.") | |
return None | |
return str(self._mask_token) | |
def mask_token(self, value): | |
""" | |
Overriding the default behavior of the mask token to have it eat the space before it. | |
This is needed to preserve backward compatibility with all the previously used models based on Roberta. | |
""" | |
# Mask token behave like a normal word, i.e. include the space before it | |
# So we set lstrip to True | |
value = AddedToken(value, lstrip=True, rstrip=False) if isinstance(value, str) else value | |
self._mask_token = value | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast._batch_encode_plus with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def _batch_encode_plus(self, *args, **kwargs) -> BatchEncoding: | |
is_split_into_words = kwargs.get("is_split_into_words", False) | |
assert self.add_prefix_space or not is_split_into_words, ( | |
f"You need to instantiate {self.__class__.__name__} with add_prefix_space=True " | |
"to use it with pretokenized inputs." | |
) | |
return super()._batch_encode_plus(*args, **kwargs) | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast._encode_plus with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def _encode_plus(self, *args, **kwargs) -> BatchEncoding: | |
is_split_into_words = kwargs.get("is_split_into_words", False) | |
assert self.add_prefix_space or not is_split_into_words, ( | |
f"You need to instantiate {self.__class__.__name__} with add_prefix_space=True " | |
"to use it with pretokenized inputs." | |
) | |
return super()._encode_plus(*args, **kwargs) | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast.save_vocabulary with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]: | |
files = self._tokenizer.model.save(save_directory, name=filename_prefix) | |
return tuple(files) | |
# Copied from transformers.models.roberta.tokenization_roberta_fast.RobertaTokenizerFast.create_token_type_ids_from_sequences with Roberta->Blenderbot, RoBERTa->Blenderbot | |
def create_token_type_ids_from_sequences( | |
self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None | |
) -> List[int]: | |
""" | |
Create a mask from the two sequences passed to be used in a sequence-pair classification task. Blenderbot does | |
not make use of token type ids, therefore a list of zeros is returned. | |
Args: | |
token_ids_0 (`List[int]`): | |
List of IDs. | |
token_ids_1 (`List[int]`, *optional*): | |
Optional second list of IDs for sequence pairs. | |
Returns: | |
`List[int]`: List of zeros. | |
""" | |
sep = [self.sep_token_id] | |
cls = [self.cls_token_id] | |
if token_ids_1 is None: | |
return len(cls + token_ids_0 + sep) * [0] | |
return len(cls + token_ids_0 + sep + sep + token_ids_1 + sep) * [0] | |
def build_inputs_with_special_tokens(self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None): | |
""" | |
Build model inputs from a sequence or a pair of sequence for sequence classification tasks by concatenating and | |
adding special tokens. A Blenderbot sequence has the following format: | |
- single sequence: ` X </s>` | |
Args: | |
token_ids_0 (`List[int]`): | |
List of IDs to which the special tokens will be added | |
token_ids_1 (`List[int]`, *optional*): | |
Will be ignored | |
Returns: | |
`List[int]`: list of [input IDs](../glossary#input-ids) with the appropriate special tokens. | |
""" | |
return token_ids_0 + [self.eos_token_id] | |
# Copied from transformers.models.blenderbot.tokenization_blenderbot.BlenderbotTokenizer.default_chat_template | |
def default_chat_template(self): | |
""" | |
A very simple chat template that just adds whitespace between messages. | |
""" | |
return ( | |
"{% for message in messages %}" | |
"{% if message['role'] == 'user' %}{{ ' ' }}{% endif %}" | |
"{{ message['content'] }}" | |
"{% if not loop.last %}{{ ' ' }}{% endif %}" | |
"{% endfor %}" | |
"{{ eos_token }}" | |
) | |