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import os | |
import tiktoken | |
from logging import getLogger | |
from pathlib import Path | |
from typing import ( | |
cast, | |
Tuple, | |
Dict, | |
Iterator, | |
List, | |
Union, | |
Optional, | |
) | |
from shutil import copyfile | |
from tiktoken.load import load_tiktoken_bpe | |
from tokenizers import AddedToken | |
from transformers.tokenization_utils import PreTrainedTokenizer | |
from transformers.utils import to_py_obj | |
from transformers.models.gpt2.tokenization_gpt2 import bytes_to_unicode | |
logger = getLogger(__name__) | |
VOCAB_FILES_NAMES = {"vocab_file": "tiktoken.model"} | |
SPIECE_UNDERLINE = "▁" | |
class TikTokenTokenizer(PreTrainedTokenizer): | |
""" | |
Tokenizing and encoding/decoding text using the Tiktoken tokenizer. See megatron/tokenizer/tiktoken_tokenizer.py. | |
This tokenizer inherits from [`PreTrainedTokenizer`] which contains most of the main methods. Users should refer to | |
this superclass for more information regarding those methods. | |
Args: | |
vocab_file (`str`): | |
The path to the Tiktoken model file. | |
bos_token (`str` or `tokenizers.AddedToken`, *optional*, defaults to `"<|begin_of_text|>",`): | |
The beginning of sequence token that was used during pretraining. Can be used a sequence classifier token. | |
eos_token (`str` or `tokenizers.AddedToken`, *optional*, defaults to `"<|end_of_text|>"`): | |
The end of sequence token. | |
unk_token (`str` or `tokenizers.AddedToken`, *optional*, defaults to `"<|reserved_special_token_249|>"`): | |
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. The second to last item in special_tokens. | |
pad_token (`str` or `tokenizers.AddedToken`, *optional*, defaults to `"<|reserved_special_token_250|>"`): | |
The token used for padding, for example when batching sequences of different lengths. | |
additional_special_tokens (list of `str`, *optional*): | |
A tuple or a list of additional tokens, which will be marked as `special`, meaning that they will be | |
skipped when decoding if `skip_special_tokens` is set to `True`. | |
""" | |
vocab_files_names = VOCAB_FILES_NAMES | |
model_input_names = ["input_ids", "attention_mask"] | |
special_tokens: Dict[str, int] | |
num_reserved_special_tokens = 256 | |
pat_str = "|".join( | |
[ | |
r"""[\p{Han}]+""", | |
r"""[^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}&&[^\p{Han}]]*[\p{Ll}\p{Lm}\p{Lo}\p{M}&&[^\p{Han}]]+(?i:'s|'t|'re|'ve|'m|'ll|'d)?""", | |
r"""[^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}&&[^\p{Han}]]+[\p{Ll}\p{Lm}\p{Lo}\p{M}&&[^\p{Han}]]*(?i:'s|'t|'re|'ve|'m|'ll|'d)?""", | |
r"""\p{N}{1,3}""", | |
r""" ?[^\s\p{L}\p{N}]+[\r\n]*""", | |
r"""\s*[\r\n]+""", | |
r"""\s+(?!\S)""", | |
r"""\s+""", | |
] | |
) | |
def __init__( | |
self, | |
vocab_file, | |
bos_token: Union[str, AddedToken] = "[BOS]", | |
eos_token: Union[str, AddedToken] = "[EOS]", | |
unk_token: Union[str, AddedToken] = "[UNK]", | |
pad_token: Union[str, AddedToken] = "[PAD]", | |
additional_special_tokens: Optional[List[str]] = None, | |
added_tokens_decoder: Optional[dict] = None, | |
**kwargs, | |
): | |
assert os.path.isfile(vocab_file), vocab_file | |
if additional_special_tokens is None: | |
additional_special_tokens = [ | |
"<|im_end|>", | |
"<|im_middle|>", | |
"<|im_user|>", | |
"<|im_assistant|>", | |
"<|im_system|>", | |
] | |
special_tokens_mapping = { | |
i: added_tokens_decoder[i].content for i in added_tokens_decoder | |
} | |
special_tokens = ( | |
[str(bos_token), str(eos_token)] | |
+ additional_special_tokens | |
+ [str(unk_token), str(pad_token)] | |
) | |
self.vocab_file = vocab_file | |
mergeable_ranks = load_tiktoken_bpe(vocab_file) | |
num_base_tokens = len(mergeable_ranks) | |
self.special_tokens = { | |
special_tokens_mapping.get(i, f"<|reserved_token_{i}|>"): i | |
for i in range( | |
num_base_tokens, num_base_tokens + self.num_reserved_special_tokens + 2 | |
) | |
} | |
self.model = tiktoken.Encoding( | |
name=Path(vocab_file).name, | |
pat_str=self.pat_str, | |
mergeable_ranks=mergeable_ranks, | |
special_tokens=self.special_tokens, | |
) | |
logger.info(f"Reloaded tiktoken model from {vocab_file}") | |
self.n_words: int = self.model.n_vocab | |
# BOS / EOS token IDs | |
self.bos_id: int = self.special_tokens[str(bos_token)] | |
self.eos_id: int = self.special_tokens[str(eos_token)] | |
logger.info( | |
f"#words: {self.n_words} - BOS ID: {self.bos_id} - EOS ID: {self.eos_id}" | |
) | |
self.pad_id: int = self.special_tokens[str(pad_token)] | |
self.unk_id: int = self.special_tokens[str(unk_token)] | |
self.byte_encoder = bytes_to_unicode() | |
self.byte_decoder = {v: k for k, v in self.byte_encoder.items()} | |
self.decoder = {} | |
for i in range(self.n_words): | |
# Taken from https://gist.github.com/xenova/a452a6474428de0182b17605a98631ee | |
decoding = "".join( | |
[ | |
self.byte_encoder[ord(char)] | |
for char in self.model.decode_single_token_bytes(i).decode( | |
"latin-1" | |
) | |
] | |
) | |
self.decoder[i] = decoding | |
self.encoder = {} | |
for i in range(self.n_words): | |
if i in self.decoder: | |
self.encoder[self.decoder[i]] = i | |
super().__init__( | |
bos_token=bos_token, | |
eos_token=eos_token, | |
unk_token=unk_token, | |
pad_token=pad_token, | |
additional_special_tokens=additional_special_tokens, | |
**kwargs, | |
) | |
self.all_special_ids_set = set(self.all_special_ids) | |
def encode( | |
self, text: str, allow_special_tokens: bool = True, **kwargs | |
) -> List[int]: | |
""" | |
Encodes a string into a list of token IDs. | |
Args: | |
text (str): The input string to be encoded. | |
Returns: | |
list[int]: A list of token IDs. | |
""" | |
# If there are other args, we should call super().encode because there are a lot of code | |
# to handle those args. supper().encode finally will call _tokenize and _convert_token_to_id. | |
if len(kwargs) > 0: | |
return super().encode(text, **kwargs) | |
assert type(text) is str | |
# The tiktoken tokenizer can handle <=400k chars without | |
# pyo3_runtime.PanicException. | |
TIKTOKEN_MAX_ENCODE_CHARS = 400_000 | |
# https://github.com/openai/tiktoken/issues/195 | |
# Here we iterate over subsequences and split if we exceed the limit | |
# of max consecutive non-whitespace or whitespace characters. | |
MAX_NO_WHITESPACES_CHARS = 25_000 | |
substrs = ( | |
substr | |
for i in range(0, len(text), TIKTOKEN_MAX_ENCODE_CHARS) | |
for substr in self._split_whitespaces_or_nonwhitespaces( | |
text[i : i + TIKTOKEN_MAX_ENCODE_CHARS], MAX_NO_WHITESPACES_CHARS | |
) | |
) | |
t: List[int] = [] | |
for substr in substrs: | |
if allow_special_tokens: | |
t.extend( | |
# we should consider special token as a common token | |
self.model.encode( | |
substr, | |
allowed_special="all", | |
) | |
) | |
else: | |
t.extend( | |
# we should consider special token as a common token | |
self.model.encode( | |
substr, | |
disallowed_special=(), | |
) | |
) | |
return t | |
def decode(self, token_ids: Union[int, List[int]], **kwargs) -> str: | |
""" | |
Decodes a list of token IDs into a string. | |
Args: | |
t (List[int]): The list of token IDs to be decoded. | |
Returns: | |
str: The decoded string. | |
""" | |
# If there are other args, we should call super().decode because there are a lot of code | |
# to handle those args. supper().encode finally will call convert_tokens_to_string and _convert_id_to_token. | |
if len(kwargs) > 0: | |
return super().decode(token_ids, **kwargs) | |
token_ids = to_py_obj(token_ids) | |
if type(token_ids) is int: | |
token_ids = [token_ids] | |
return self.model.decode(cast(List[int], token_ids)) | |
def _split_whitespaces_or_nonwhitespaces( | |
s: str, max_consecutive_slice_len: int | |
) -> Iterator[str]: | |
""" | |
Splits the string `s` so that each substring contains no more than `max_consecutive_slice_len` | |
consecutive whitespaces or consecutive non-whitespaces. | |
""" | |
current_slice_len = 0 | |
current_slice_is_space = s[0].isspace() if len(s) > 0 else False | |
slice_start = 0 | |
for i in range(len(s)): | |
is_now_space = s[i].isspace() | |
if current_slice_is_space ^ is_now_space: | |
current_slice_len = 1 | |
current_slice_is_space = is_now_space | |
else: | |
current_slice_len += 1 | |
if current_slice_len > max_consecutive_slice_len: | |
yield s[slice_start:i] | |
slice_start = i | |
current_slice_len = 1 | |
yield s[slice_start:] | |
""" ----- Below are the abstract methods required by PreTrainedTokenizer ----- """ | |
def vocab_size(self) -> int: | |
return self.n_words | |
def get_vocab(self) -> Dict[str, int]: | |
return self.encoder | |
def _tokenize(self, text: str, **kwargs) -> List[str]: | |
return [self.decoder[t] for t in self.encode(text)] | |
def _convert_token_to_id(self, token: str) -> int: | |
return self.encoder.get(token, self.unk_id) | |
def _convert_id_to_token(self, index: int) -> str: | |
return self.decoder.get(index) | |
def clean_up_tokenization(out_string: str) -> str: | |
return out_string | |
def convert_tokens_to_string(self, tokens: List[str]) -> str: | |
text = "".join(tokens).replace(SPIECE_UNDERLINE, "") | |
text = bytearray([self.byte_decoder[c] for c in text]).decode( | |
"utf-8", "replace" | |
) | |
return text | |
def save_vocabulary( | |
self, save_directory: str, filename_prefix: Optional[str] = None | |
) -> Tuple[str]: | |
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"], | |
) | |
if os.path.abspath(self.vocab_file) != os.path.abspath( | |
out_vocab_file | |
) and os.path.isfile(self.vocab_file): | |
copyfile(self.vocab_file, out_vocab_file) | |
return (out_vocab_file,) | |