# coding=utf-8
# Copyright 2019 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 FSMT."""
import json
import os
import re
import unicodedata
from typing import Dict, List, Optional, Tuple
import sacremoses as sm
from ...tokenization_utils import PreTrainedTokenizer
from ...utils import logging
logger = logging.get_logger(__name__)
VOCAB_FILES_NAMES = {
"src_vocab_file": "vocab-src.json",
"tgt_vocab_file": "vocab-tgt.json",
"merges_file": "merges.txt",
}
PRETRAINED_VOCAB_FILES_MAP = {
"src_vocab_file": {
"stas/tiny-wmt19-en-de": "https://huggingface.co/stas/tiny-wmt19-en-de/resolve/main/vocab-src.json"
},
"tgt_vocab_file": {
"stas/tiny-wmt19-en-de": "https://huggingface.co/stas/tiny-wmt19-en-de/resolve/main/vocab-tgt.json"
},
"merges_file": {"stas/tiny-wmt19-en-de": "https://huggingface.co/stas/tiny-wmt19-en-de/resolve/main/merges.txt"},
}
PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {"stas/tiny-wmt19-en-de": 1024}
PRETRAINED_INIT_CONFIGURATION = {
"stas/tiny-wmt19-en-de": {
"langs": ["en", "de"],
"model_max_length": 1024,
"special_tokens_map_file": None,
"full_tokenizer_file": None,
}
}
def get_pairs(word):
"""
Return set of symbol pairs in a word. word is represented as tuple of symbols (symbols being variable-length
strings)
"""
pairs = set()
prev_char = word[0]
for char in word[1:]:
pairs.add((prev_char, char))
prev_char = char
return pairs
def replace_unicode_punct(text):
"""
Port of https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/replace-unicode-punctuation.perl
"""
text = text.replace("，", ",")
text = re.sub(r"。\s*", ". ", text)
text = text.replace("、", ",")
text = text.replace("”", '"')
text = text.replace("“", '"')
text = text.replace("∶", ":")
text = text.replace("：", ":")
text = text.replace("？", "?")
text = text.replace("《", '"')
text = text.replace("》", '"')
text = text.replace("）", ")")
text = text.replace("！", "!")
text = text.replace("（", "(")
text = text.replace("；", ";")
text = text.replace("１", "1")
text = text.replace("」", '"')
text = text.replace("「", '"')
text = text.replace("０", "0")
text = text.replace("３", "3")
text = text.replace("２", "2")
text = text.replace("５", "5")
text = text.replace("６", "6")
text = text.replace("９", "9")
text = text.replace("７", "7")
text = text.replace("８", "8")
text = text.replace("４", "4")
text = re.sub(r"．\s*", ". ", text)
text = text.replace("～", "~")
text = text.replace("’", "'")
text = text.replace("…", "...")
text = text.replace("━", "-")
text = text.replace("〈", "<")
text = text.replace("〉", ">")
text = text.replace("【", "[")
text = text.replace("】", "]")
text = text.replace("％", "%")
return text
def remove_non_printing_char(text):
"""
Port of https://github.com/moses-smt/mosesdecoder/blob/master/scripts/tokenizer/remove-non-printing-char.perl
"""
output = []
for char in text:
cat = unicodedata.category(char)
if cat.startswith("C"):
continue
output.append(char)
return "".join(output)
# Porting notes:
# this one is modeled after XLMTokenizer
#
# added:
# - src_vocab_file,
# - tgt_vocab_file,
# - langs,
[docs]class FSMTTokenizer(PreTrainedTokenizer):
"""
Construct an FAIRSEQ Transformer tokenizer. Based on Byte-Pair Encoding. The tokenization process is the following:
- Moses preprocessing and tokenization.
- Normalizing all inputs text.
- The arguments ``special_tokens`` and the function ``set_special_tokens``, can be used to add additional symbols
(like "__classify__") to a vocabulary.
- The argument :obj:`langs` defines a pair of languages.
This tokenizer inherits from :class:`~transformers.PreTrainedTokenizer` which contains most of the main methods.
Users should refer to this superclass for more information regarding those methods.
Args:
langs (:obj:`List[str]`):
A list of two languages to translate from and to, for instance :obj:`["en", "ru"]`.
src_vocab_file (:obj:`str`):
File containing the vocabulary for the source language.
tgt_vocab_file (:obj:`st`):
File containing the vocabulary for the target language.
merges_file (:obj:`str`):
File containing the merges.
do_lower_case (:obj:`bool`, `optional`, defaults to :obj:`False`):
Whether or not to lowercase the input when tokenizing.
unk_token (:obj:`str`, `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.
bos_token (:obj:`str`, `optional`, defaults to :obj:`"<s>"`):
The beginning of sequence token that was used during pretraining. Can be used a sequence classifier token.
.. note::
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 :obj:`cls_token`.
sep_token (:obj:`str`, `optional`, defaults to :obj:`"</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.
pad_token (:obj:`str`, `optional`, defaults to :obj:`"<pad>"`):
The token used for padding, for example when batching sequences of different lengths.
"""
vocab_files_names = VOCAB_FILES_NAMES
pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
pretrained_init_configuration = PRETRAINED_INIT_CONFIGURATION
max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
model_input_names = ["input_ids", "attention_mask"]
def __init__(
self,
langs=None,
src_vocab_file=None,
tgt_vocab_file=None,
merges_file=None,
do_lower_case=False,
unk_token="<unk>",
bos_token="<s>",
sep_token="</s>",
pad_token="<pad>",
**kwargs
):
super().__init__(
langs=langs,
src_vocab_file=src_vocab_file,
tgt_vocab_file=tgt_vocab_file,
merges_file=merges_file,
do_lower_case=do_lower_case,
unk_token=unk_token,
bos_token=bos_token,
sep_token=sep_token,
pad_token=pad_token,
**kwargs,
)
self.src_vocab_file = src_vocab_file
self.tgt_vocab_file = tgt_vocab_file
self.merges_file = merges_file
self.do_lower_case = do_lower_case
# cache of sm.MosesPunctNormalizer instance
self.cache_moses_punct_normalizer = dict()
# cache of sm.MosesTokenizer instance
self.cache_moses_tokenizer = dict()
self.cache_moses_detokenizer = dict()
if langs and len(langs) == 2:
self.src_lang, self.tgt_lang = langs
else:
raise ValueError(
f"arg `langs` needs to be a list of 2 langs, e.g. ['en', 'ru'], but got {langs}. "
"Usually that means that tokenizer can't find a mapping for the given model path "
"in PRETRAINED_VOCAB_FILES_MAP, and other maps of this tokenizer."
)
with open(src_vocab_file, encoding="utf-8") as src_vocab_handle:
self.encoder = json.load(src_vocab_handle)
with open(tgt_vocab_file, encoding="utf-8") as tgt_vocab_handle:
tgt_vocab = json.load(tgt_vocab_handle)
self.decoder = {v: k for k, v in tgt_vocab.items()}
with open(merges_file, encoding="utf-8") as merges_handle:
merges = merges_handle.read().split("\n")[:-1]
merges = [tuple(merge.split()[:2]) for merge in merges]
self.bpe_ranks = dict(zip(merges, range(len(merges))))
self.cache = {}
# hack override
def get_vocab(self) -> Dict[str, int]:
return self.get_src_vocab()
# hack override
@property
def vocab_size(self) -> int:
return self.src_vocab_size
def moses_punct_norm(self, text, lang):
if lang not in self.cache_moses_punct_normalizer:
punct_normalizer = sm.MosesPunctNormalizer(lang=lang)
self.cache_moses_punct_normalizer[lang] = punct_normalizer
return self.cache_moses_punct_normalizer[lang].normalize(text)
def moses_tokenize(self, text, lang):
if lang not in self.cache_moses_tokenizer:
moses_tokenizer = sm.MosesTokenizer(lang=lang)
self.cache_moses_tokenizer[lang] = moses_tokenizer
return self.cache_moses_tokenizer[lang].tokenize(
text, aggressive_dash_splits=True, return_str=False, escape=True
)
def moses_detokenize(self, tokens, lang):
if lang not in self.cache_moses_tokenizer:
moses_detokenizer = sm.MosesDetokenizer(lang=self.tgt_lang)
self.cache_moses_detokenizer[lang] = moses_detokenizer
return self.cache_moses_detokenizer[lang].detokenize(tokens)
def moses_pipeline(self, text, lang):
text = replace_unicode_punct(text)
text = self.moses_punct_norm(text, lang)
text = remove_non_printing_char(text)
return text
@property
def src_vocab_size(self):
return len(self.encoder)
@property
def tgt_vocab_size(self):
return len(self.decoder)
def get_src_vocab(self):
return dict(self.encoder, **self.added_tokens_encoder)
def get_tgt_vocab(self):
return dict(self.decoder, **self.added_tokens_decoder)
def bpe(self, token):
word = tuple(token[:-1]) + (token[-1] + "</w>",)
if token in self.cache:
return self.cache[token]
pairs = get_pairs(word)
if not pairs:
return token + "</w>"
while True:
bigram = min(pairs, key=lambda pair: self.bpe_ranks.get(pair, float("inf")))
if bigram not in self.bpe_ranks:
break
first, second = bigram
new_word = []
i = 0
while i < len(word):
try:
j = word.index(first, i)
except ValueError:
new_word.extend(word[i:])
break
else:
new_word.extend(word[i:j])
i = j
if word[i] == first and i < len(word) - 1 and word[i + 1] == second:
new_word.append(first + second)
i += 2
else:
new_word.append(word[i])
i += 1
new_word = tuple(new_word)
word = new_word
if len(word) == 1:
break
else:
pairs = get_pairs(word)
word = " ".join(word)
if word == "\n </w>":
word = "\n</w>"
self.cache[token] = word
return word
def _tokenize(self, text, lang="en", bypass_tokenizer=False):
"""
Tokenize a string given language code using Moses.
Details of tokenization:
- [sacremoses](https://github.com/alvations/sacremoses): port of Moses
- Install with `pip install sacremoses`
Args:
- lang: ISO language code (default = 'en') (string). Languages should belong of the model supported
languages. However, we don't enforce it.
- bypass_tokenizer: Allow users to preprocess and tokenize the sentences externally (default = False)
(bool). If True, we only apply BPE.
Returns:
List of tokens.
"""
# ignore `lang` which is currently isn't explicitly passed in tokenization_utils.py and always results in lang=en
# if lang != self.src_lang:
# raise ValueError(f"Expected lang={self.src_lang}, but got {lang}")
lang = self.src_lang
if self.do_lower_case:
text = text.lower()
if bypass_tokenizer:
text = text.split()
else:
text = self.moses_pipeline(text, lang=lang)
text = self.moses_tokenize(text, lang=lang)
split_tokens = []
for token in text:
if token:
split_tokens.extend([t for t in self.bpe(token).split(" ")])
return split_tokens
def _convert_token_to_id(self, token):
""" Converts a token (str) in an id using the vocab. """
return self.encoder.get(token, self.encoder.get(self.unk_token))
def _convert_id_to_token(self, index):
"""Converts an index (integer) in a token (str) using the vocab."""
return self.decoder.get(index, self.unk_token)
def convert_tokens_to_string(self, tokens):
""" Converts a sequence of tokens (string) in a single string. """
# remove BPE
tokens = [t.replace(" ", "").replace("</w>", " ") for t in tokens]
tokens = "".join(tokens).split()
# detokenize
text = self.moses_detokenize(tokens, self.tgt_lang)
return text
[docs] 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 (:obj:`List[int]`):
List of IDs.
token_ids_1 (:obj:`List[int]`, `optional`):
Optional second list of IDs for sequence pairs.
already_has_special_tokens (:obj:`bool`, `optional`, defaults to :obj:`False`):
Whether or not the token list is already formatted with special tokens for the model.
Returns:
:obj:`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:
if token_ids_1 is not None:
raise ValueError(
"You should not supply a second sequence if the provided sequence of "
"ids is already formatted with special tokens for the model."
)
return list(
map(
lambda x: 1 if x in [self.sep_token_id, self.cls_token_id] else 0,
token_ids_0,
)
)
# no bos used in fairseq
if token_ids_1 is not None:
return ([0] * len(token_ids_0)) + [1] + ([0] * len(token_ids_1)) + [1]
return ([0] * len(token_ids_0)) + [1]
[docs] 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. A FAIRSEQ
Transformer sequence pair mask has the following format:
::
0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1
| first sequence | second sequence |
If :obj:`token_ids_1` is :obj:`None`, this method only returns the first portion of the mask (0s).
Args:
token_ids_0 (:obj:`List[int]`):
List of IDs.
token_ids_1 (:obj:`List[int]`, `optional`):
Optional second list of IDs for sequence pairs.
Returns:
:obj:`List[int]`: List of `token type IDs <../glossary.html#token-type-ids>`_ according to the given
sequence(s).
Creates a mask from the two sequences passed to be used in a sequence-pair classification task. An
FAIRSEQ_TRANSFORMER sequence pair mask has the following format:
"""
sep = [self.sep_token_id]
# no bos used in fairseq
if token_ids_1 is None:
return len(token_ids_0 + sep) * [0]
return len(token_ids_0 + sep) * [0] + len(token_ids_1 + sep) * [1]
[docs] 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
src_vocab_file = os.path.join(
save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["src_vocab_file"]
)
tgt_vocab_file = os.path.join(
save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["tgt_vocab_file"]
)
merges_file = os.path.join(
save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["merges_file"]
)
with open(src_vocab_file, "w", encoding="utf-8") as f:
f.write(json.dumps(self.encoder, ensure_ascii=False))
with open(tgt_vocab_file, "w", encoding="utf-8") as f:
tgt_vocab = {v: k for k, v in self.decoder.items()}
f.write(json.dumps(tgt_vocab, ensure_ascii=False))
index = 0
with open(merges_file, "w", encoding="utf-8") as writer:
for bpe_tokens, token_index in sorted(self.bpe_ranks.items(), key=lambda kv: kv[1]):
if index != token_index:
logger.warning(
f"Saving vocabulary to {merges_file}: BPE merge indices are not consecutive."
" Please check that the tokenizer is not corrupted!"
)
index = token_index
writer.write(" ".join(bpe_tokens) + "\n")
index += 1
return src_vocab_file, tgt_vocab_file, merges_file