# coding=utf-8
# Copyright (c) 2020, VinAI Research and the HuggingFace Inc. team.
# Copyright 2018 The Open AI Team Authors and The HuggingFace Inc. team.
#
# 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.
""" Tokenization classes for PhoBERT"""
import os
from collections import defaultdict
from shutil import copyfile
from typing import Any, Dict, List, Optional, Tuple, Union
from transformers.tokenization_utils_base import EncodingFast
from transformers.tokenization_utils_fast import PreTrainedTokenizerFast
from transformers.utils import logging
from .tokenization_phobert import PhobertTokenizer
logger = logging.get_logger(__name__)
VOCAB_FILES_NAMES = {
"vocab_file": "vocab.txt",
"merges_file": "bpe.codes",
"tokenizer_file": "tokenizer.json",
}
PRETRAINED_VOCAB_FILES_MAP = {
"vocab_file": {
"vinai/phobert-base": "https://huggingface.co/vinai/phobert-base/resolve/main/vocab.txt",
"vinai/phobert-large": "https://huggingface.co/vinai/phobert-large/resolve/main/vocab.txt",
},
"merges_file": {
"vinai/phobert-base": "https://huggingface.co/vinai/phobert-base/resolve/main/bpe.codes",
"vinai/phobert-large": "https://huggingface.co/vinai/phobert-large/resolve/main/bpe.codes",
},
"tokenizer_file": {
"vinai/phobert-base": "https://huggingface.co/vinai/phobert-base/resolve/main/tokenizer.json",
"vinai/phobert-large": "https://huggingface.co/vinai/phobert-large/resolve/main/tokenizer.json",
},
}
PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
"vinai/phobert-base": 256,
"vinai/phobert-large": 256,
}
class PhobertTokenizerFast(PreTrainedTokenizerFast):
"""
Construct a "Fast" BPE tokenizer for PhoBERT (backed by HuggingFace's *tokenizers* library).
Peculiarities:
- uses BERT's pre-tokenizer: BertPreTokenizer splits tokens on spaces, and also on punctuation. Each occurrence of
a punctuation character will be treated separately.
This tokenizer inherits from [`PreTrainedTokenizer`] which contains most of the methods. Users should refer to the
superclass for more information regarding methods.
Args:
vocab_file (`str`):
Path to the vocabulary file.
merges_file (`str`):
Path to the merges file.
"""
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 = PhobertTokenizer
def __init__(
self,
vocab_file=None,
merges_file=None,
tokenizer_file=None,
bos_token="<s>",
eos_token="</s>",
sep_token="</s>",
cls_token="<s>",
unk_token="<unk>",
pad_token="<pad>",
mask_token="<mask>",
**kwargs
):
super().__init__(
vocab_file,
merges_file,
tokenizer_file=tokenizer_file,
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,
**kwargs,
)
self.vocab_file = vocab_file
self.merges_file = merges_file
self.can_save_slow_tokenizer = False if not self.vocab_file else True
def get_added_vocab_hacking(self):
"""
Returns the added tokens in the vocabulary as a dictionary of token to index.
Returns:
`Dict[str, int], Dict[int, int]`: The added tokens, and their original and new ids
"""
base_vocab_size = self._tokenizer.get_vocab_size(with_added_tokens=False)
full_vocab_size = self._tokenizer.get_vocab_size(with_added_tokens=True)
if full_vocab_size == base_vocab_size:
return {}, {}
# Tokens in added_vocab should have ids that are equal to or larger than the size of base_vocab
added_vocab = dict(
(self._tokenizer.id_to_token(index), index + 1 - base_vocab_size + self.mask_token_id)
for index in range(base_vocab_size, full_vocab_size)
)
id_mapping = dict((index, self._tokenizer.token_to_id(tok)) for tok, index in added_vocab.items())
return added_vocab, id_mapping
def _decode(
self,
token_ids: Union[int, List[int]],
skip_special_tokens: bool = False,
clean_up_tokenization_spaces: bool = True,
**kwargs
) -> str:
self._decode_use_source_tokenizer = kwargs.pop("use_source_tokenizer", False)
if isinstance(token_ids, int):
token_ids = [token_ids]
# Mapping ids into their original values
_, id_mapping = self.get_added_vocab_hacking()
if len(id_mapping) > 0:
token_ids = [id_mapping[id] if id in id_mapping else id for id in token_ids]
text = self._tokenizer.decode(token_ids, skip_special_tokens=skip_special_tokens)
if clean_up_tokenization_spaces:
clean_text = self.clean_up_tokenization(text)
return clean_text
else:
return text
def _convert_encoding(
self,
encoding: EncodingFast,
return_token_type_ids: Optional[bool] = None,
return_attention_mask: Optional[bool] = None,
return_overflowing_tokens: bool = False,
return_special_tokens_mask: bool = False,
return_offsets_mapping: bool = False,
return_length: bool = False,
verbose: bool = True,
) -> Tuple[Dict[str, Any], List[EncodingFast]]:
"""
Convert the encoding representation (from low-level HuggingFace tokenizer output) to a python Dict and a list
of encodings, take care of building a batch from overflowing tokens.
Overflowing tokens are converted to additional examples (like batches) so the output values of the dict are
lists (overflows) of lists (tokens).
Output shape: (overflows, sequence length)
"""
if return_token_type_ids is None:
return_token_type_ids = "token_type_ids" in self.model_input_names
if return_attention_mask is None:
return_attention_mask = "attention_mask" in self.model_input_names
if return_overflowing_tokens and encoding.overflowing is not None:
encodings = [encoding] + encoding.overflowing
else:
encodings = [encoding]
encoding_dict = defaultdict(list)
added_vocab, _ = self.get_added_vocab_hacking()
for e in encodings:
# encoding_dict["input_ids"].append(e.ids)
# Reassign ids of tokens due to the hacking strategy
ids = []
for id, token in zip(e.ids, e.tokens):
if id <= self.mask_token_id:
ids.append(id)
else:
if token.strip() in added_vocab:
ids.append(added_vocab[token.strip()])
else:
ids.append(self.unk_token_id)
encoding_dict["input_ids"].append(ids)
if return_token_type_ids:
encoding_dict["token_type_ids"].append(e.type_ids)
if return_attention_mask:
encoding_dict["attention_mask"].append(e.attention_mask)
if return_special_tokens_mask:
encoding_dict["special_tokens_mask"].append(e.special_tokens_mask)
if return_offsets_mapping:
encoding_dict["offset_mapping"].append(e.offsets)
if return_length:
# encoding_dict["length"].append(len(e.ids))
encoding_dict["length"].append(len(ids))
return encoding_dict, encodings
def build_inputs_with_special_tokens(
self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None
) -> List[int]:
"""
Build model inputs from a sequence or a pair of sequence for sequence classification tasks by concatenating and
adding special tokens. A PhoBERT sequence has the following format:
- single sequence: `<s> X </s>`
- pair of sequences: `<s> A </s></s> B </s>`
Args:
token_ids_0 (`List[int]`):
List of IDs to which the special tokens will be added.
token_ids_1 (`List[int]`, *optional*):
Optional second list of IDs for sequence pairs.
Returns:
`List[int]`: List of [input IDs](../glossary#input-ids) with the appropriate special tokens.
"""
if token_ids_1 is None:
return [self.cls_token_id] + token_ids_0 + [self.sep_token_id]
cls = [self.cls_token_id]
sep = [self.sep_token_id]
return cls + token_ids_0 + sep + sep + token_ids_1 + sep
def get_special_tokens_mask(
self, token_ids_0: List[int], token_ids_1: Optional[List[int]] = None, already_has_special_tokens: bool = False
) -> List[int]:
"""
Retrieve sequence ids from a token list that has no special tokens added. This method is called when adding
special tokens using the tokenizer `prepare_for_model` method.
Args:
token_ids_0 (`List[int]`):
List of IDs.
token_ids_1 (`List[int]`, *optional*):
Optional second list of IDs for sequence pairs.
already_has_special_tokens (`bool`, *optional*, defaults to `False`):
Whether or not the token list is already formatted with special tokens for the model.
Returns:
`List[int]`: A list of integers in the range [0, 1]: 1 for a special token, 0 for a sequence token.
"""
if already_has_special_tokens:
return super().get_special_tokens_mask(
token_ids_0=token_ids_0, token_ids_1=token_ids_1, already_has_special_tokens=True
)
if token_ids_1 is None:
return [1] + ([0] * len(token_ids_0)) + [1]
return [1] + ([0] * len(token_ids_0)) + [1, 1] + ([0] * len(token_ids_1)) + [1]
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. PhoBERT 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 save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]:
if not self.can_save_slow_tokenizer:
raise ValueError(
"Your fast tokenizer does not have the necessary information to save the vocabulary for a slow "
"tokenizer."
)
if not os.path.isdir(save_directory):
logger.error(f"Vocabulary path ({save_directory}) should be a directory.")
return
out_vocab_file = os.path.join(
save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["vocab_file"]
)
out_merges_file = os.path.join(
save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["merges_file"]
)
if os.path.abspath(self.vocab_file) != os.path.abspath(out_vocab_file):
copyfile(self.vocab_file, out_vocab_file)
if os.path.abspath(self.merges_file) != os.path.abspath(out_merges_file):
copyfile(self.merges_file, out_merges_file)
return (out_vocab_file, out_merges_file)