Source code for transformers.models.mbart.tokenization_mbart_fast

# coding=utf-8
# Copyright 2020 The Facebook AI Research Team Authors and The HuggingFace Inc. team.
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#     http://www.apache.org/licenses/LICENSE-2.0
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from typing import List, Optional

from tokenizers import processors

from ...file_utils import add_start_docstrings, is_sentencepiece_available
from ...tokenization_utils import BatchEncoding
from ...tokenization_utils_base import PREPARE_SEQ2SEQ_BATCH_DOCSTRING
from ...utils import logging
from ..xlm_roberta.tokenization_xlm_roberta_fast import XLMRobertaTokenizerFast


if is_sentencepiece_available():
    from .tokenization_mbart import MBartTokenizer
else:
    MBartTokenizer = None


logger = logging.get_logger(__name__)

_all_mbart_models = ["facebook/mbart-large-en-ro", "facebook/mbart-large-cc25"]
SPM_URL = "https://huggingface.co/facebook/mbart-large-en-ro/resolve/main/sentence.bpe.model"
tokenizer_URL = "https://huggingface.co/facebook/mbart-large-en-ro/resolve/main/tokenizer.json"

FAIRSEQ_LANGUAGE_CODES = [
    "ar_AR",
    "cs_CZ",
    "de_DE",
    "en_XX",
    "es_XX",
    "et_EE",
    "fi_FI",
    "fr_XX",
    "gu_IN",
    "hi_IN",
    "it_IT",
    "ja_XX",
    "kk_KZ",
    "ko_KR",
    "lt_LT",
    "lv_LV",
    "my_MM",
    "ne_NP",
    "nl_XX",
    "ro_RO",
    "ru_RU",
    "si_LK",
    "tr_TR",
    "vi_VN",
    "zh_CN",
]


[docs]class MBartTokenizerFast(XLMRobertaTokenizerFast): """ Construct a "fast" MBART tokenizer (backed by HuggingFace's `tokenizers` library). Based on `BPE <https://huggingface.co/docs/tokenizers/python/latest/components.html?highlight=BPE#models>`__. :class:`~transformers.MBartTokenizerFast` is a subclass of :class:`~transformers.XLMRobertaTokenizerFast` and adds a new :meth:`~transformers.MBartTokenizerFast.prepare_seq2seq_batch`. Refer to superclass :class:`~transformers.XLMRobertaTokenizerFast` for usage examples and documentation concerning the initialization parameters and other methods. .. warning:: ``prepare_seq2seq_batch`` should be used to encode inputs. Other tokenizer methods like ``encode`` do not work properly. The tokenization method is ``<tokens> <eos> <language code>`` for source language documents, and ``<language code> <tokens> <eos>``` for target language documents. Examples:: >>> from transformers import MBartTokenizerFast >>> tokenizer = MBartTokenizerFast.from_pretrained('facebook/mbart-large-en-ro') >>> example_english_phrase = " UN Chief Says There Is No Military Solution in Syria" >>> expected_translation_romanian = "Şeful ONU declară că nu există o soluţie militară în Siria" >>> batch: dict = tokenizer.prepare_seq2seq_batch( ... example_english_phrase, src_lang="en_XX", tgt_lang="ro_RO", tgt_texts=expected_translation_romanian, return_tensors="pt" ... ) """ vocab_files_names = {"vocab_file": "sentencepiece.bpe.model"} max_model_input_sizes = {m: 1024 for m in _all_mbart_models} pretrained_vocab_files_map = {"vocab_file": {m: SPM_URL for m in _all_mbart_models}} slow_tokenizer_class = MBartTokenizer prefix_tokens: List[int] = [] suffix_tokens: List[int] = [] def __init__(self, *args, tokenizer_file=None, **kwargs): super().__init__(*args, tokenizer_file=tokenizer_file, **kwargs) self.cur_lang_code = self.convert_tokens_to_ids("en_XX") self.set_src_lang_special_tokens(kwargs.get("src_lang", "en_XX")) self.add_special_tokens({"additional_special_tokens": FAIRSEQ_LANGUAGE_CODES})
[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]: """ Retrieves 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)) prefix_ones = [1] * len(self.prefix_tokens) suffix_ones = [1] * len(self.suffix_tokens) if token_ids_1 is None: return prefix_ones + ([0] * len(token_ids_0)) + suffix_ones return prefix_ones + ([0] * len(token_ids_0)) + ([0] * len(token_ids_1)) + suffix_ones
[docs] 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. The special tokens depend on calling set_lang. An MBART sequence has the following format, where ``X`` represents the sequence: - ``input_ids`` (for encoder) ``X [eos, src_lang_code]`` - ``decoder_input_ids``: (for decoder) ``X [eos, tgt_lang_code]`` BOS is never used. Pairs of sequences are not the expected use case, but they will be handled without a separator. Args: token_ids_0 (:obj:`List[int]`): List of IDs to which the special tokens will be added. token_ids_1 (:obj:`List[int]`, `optional`): Optional second list of IDs for sequence pairs. Returns: :obj:`List[int]`: list of `input IDs <../glossary.html#input-ids>`__ with the appropriate special tokens. """ if token_ids_1 is None: return self.prefix_tokens + token_ids_0 + self.suffix_tokens # We don't expect to process pairs, but leave the pair logic for API consistency return self.prefix_tokens + token_ids_0 + token_ids_1 + self.suffix_tokens
[docs] @add_start_docstrings(PREPARE_SEQ2SEQ_BATCH_DOCSTRING) def prepare_seq2seq_batch( self, src_texts: List[str], src_lang: str = "en_XX", tgt_texts: Optional[List[str]] = None, tgt_lang: str = "ro_RO", max_length: Optional[int] = None, max_target_length: Optional[int] = None, truncation: bool = True, padding: str = "longest", return_tensors: str = None, **kwargs, ) -> BatchEncoding: if max_length is None: max_length = self.model_max_length self.set_src_lang_special_tokens(src_lang) model_inputs: BatchEncoding = self( src_texts, add_special_tokens=True, return_tensors=return_tensors, max_length=max_length, padding=padding, truncation=truncation, **kwargs, ) if tgt_texts is None: return model_inputs # Process tgt_texts if max_target_length is None: max_target_length = max_length self.set_tgt_lang_special_tokens(tgt_lang) labels = self( tgt_texts, add_special_tokens=True, return_tensors=return_tensors, padding=padding, max_length=max_target_length, truncation=True, **kwargs, )["input_ids"] model_inputs["labels"] = labels self.set_src_lang_special_tokens(src_lang) # sets to src_lang return model_inputs
[docs] def set_src_lang_special_tokens(self, src_lang) -> None: """Reset the special tokens to the source lang setting. No prefix and suffix=[eos, src_lang_code].""" self.cur_lang_code = self.convert_tokens_to_ids(src_lang) self.prefix_tokens = [] self.suffix_tokens = [self.eos_token_id, self.cur_lang_code] prefix_tokens_str = self.convert_ids_to_tokens(self.prefix_tokens) suffix_tokens_str = self.convert_ids_to_tokens(self.suffix_tokens) self._tokenizer.post_processor = processors.TemplateProcessing( single=prefix_tokens_str + ["$A"] + suffix_tokens_str, pair=prefix_tokens_str + ["$A", "$B"] + suffix_tokens_str, special_tokens=list(zip(prefix_tokens_str + suffix_tokens_str, self.prefix_tokens + self.suffix_tokens)), )
[docs] def set_tgt_lang_special_tokens(self, lang: str) -> None: """Reset the special tokens to the target language setting. No prefix and suffix=[eos, tgt_lang_code].""" self.cur_lang_code = self.convert_tokens_to_ids(lang) self.prefix_tokens = [] self.suffix_tokens = [self.eos_token_id, self.cur_lang_code] prefix_tokens_str = self.convert_ids_to_tokens(self.prefix_tokens) suffix_tokens_str = self.convert_ids_to_tokens(self.suffix_tokens) self._tokenizer.post_processor = processors.TemplateProcessing( single=prefix_tokens_str + ["$A"] + suffix_tokens_str, pair=prefix_tokens_str + ["$A", "$B"] + suffix_tokens_str, special_tokens=list(zip(prefix_tokens_str + suffix_tokens_str, self.prefix_tokens + self.suffix_tokens)), )