Add sentencepiece to BertJapaneseTokenizer (#19769)

* support sentencepiece for bertjapanesetokenizer

* add test vocab file for sentencepiece, bertjapanesetokenizer

* make BasicTokenizer be identical to transformers.models.bert.tokenization_bert.BasicTokenizer

* fix missing of \n in comment

* fix init argument missing in tests

* make spm_file be optional, exclude spiece.model from tests/fixtures, and add description comments

* make comment length less than 119

* apply doc style check

src/transformers/models/bert_japanese/tokenization_bert_japanese.py

@@ -19,7 +19,9 @@ import collections
 import copy
 import os
 import unicodedata
-from typing import List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Tuple
+
+import sentencepiece as spm
 
 from ...tokenization_utils import PreTrainedTokenizer, _is_control, _is_punctuation, _is_whitespace
 from ...utils import logging
@@ -27,7 +29,9 @@ from ...utils import logging
 
 logger = logging.get_logger(__name__)
 
-VOCAB_FILES_NAMES = {"vocab_file": "vocab.txt"}
+VOCAB_FILES_NAMES = {"vocab_file": "vocab.txt", "spm_file": "spiece.model"}
+
+SPIECE_UNDERLINE = "▁"
 
 PRETRAINED_VOCAB_FILES_MAP = {
     "vocab_file": {
@@ -107,6 +111,9 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
     Args:
         vocab_file (`str`):
             Path to a one-wordpiece-per-line vocabulary file.
+        spm_file (`str`, *optional*):
+            Path to [SentencePiece](https://github.com/google/sentencepiece) file (generally has a .spm or .model
+            extension) that contains the vocabulary.
         do_lower_case (`bool`, *optional*, defaults to `True`):
             Whether to lower case the input. Only has an effect when do_basic_tokenize=True.
         do_word_tokenize (`bool`, *optional*, defaults to `True`):
@@ -116,7 +123,7 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
         word_tokenizer_type (`str`, *optional*, defaults to `"basic"`):
             Type of word tokenizer. Choose from ["basic", "mecab", "sudachi", "jumanpp"].
         subword_tokenizer_type (`str`, *optional*, defaults to `"wordpiece"`):
-            Type of subword tokenizer. Choose from ["wordpiece", "character"].
+            Type of subword tokenizer. Choose from ["wordpiece", "character", "sentencepiece",].
         mecab_kwargs (`dict`, *optional*):
             Dictionary passed to the `MecabTokenizer` constructor.
         sudachi_kwargs (`dict`, *optional*):
@@ -133,6 +140,7 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
     def __init__(
         self,
         vocab_file,
+        spm_file=None,
         do_lower_case=False,
         do_word_tokenize=True,
         do_subword_tokenize=True,
@@ -150,6 +158,7 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
         **kwargs
     ):
         super().__init__(
+            spm_file=spm_file,
             unk_token=unk_token,
             sep_token=sep_token,
             pad_token=pad_token,
@@ -167,10 +176,18 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
             **kwargs,
         )
 
+        if subword_tokenizer_type == "sentencepiece":
+            if not os.path.isfile(spm_file):
+                raise ValueError(
+                    f"Can't find a vocabulary file at path '{spm_file}'. To load the vocabulary from a Google"
+                    " pretrained model use `tokenizer = AutoTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`"
+                )
+            self.spm_file = spm_file
+        else:
             if not os.path.isfile(vocab_file):
                 raise ValueError(
-                f"Can't find a vocabulary file at path '{vocab_file}'. To load the vocabulary from a Google pretrained"
-                " model use `tokenizer = AutoTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`"
+                    f"Can't find a vocabulary file at path '{vocab_file}'. To load the vocabulary from a Google"
+                    " pretrained model use `tokenizer = AutoTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`"
                 )
             self.vocab = load_vocab(vocab_file)
             self.ids_to_tokens = collections.OrderedDict([(ids, tok) for tok, ids in self.vocab.items()])
@@ -209,6 +226,8 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
                 self.subword_tokenizer = WordpieceTokenizer(vocab=self.vocab, unk_token=self.unk_token)
             elif subword_tokenizer_type == "character":
                 self.subword_tokenizer = CharacterTokenizer(vocab=self.vocab, unk_token=self.unk_token)
+            elif subword_tokenizer_type == "sentencepiece":
+                self.subword_tokenizer = SentencepieceTokenizer(vocab=self.spm_file, unk_token=self.unk_token)
             else:
                 raise ValueError(f"Invalid subword_tokenizer_type '{subword_tokenizer_type}' is specified.")
 
@@ -251,27 +270,34 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
         return split_tokens
 
     @property
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer.vocab_size
     def vocab_size(self):
+        if self.subword_tokenizer_type == "sentencepiece":
+            return len(self.subword_tokenizer.sp_model)
         return len(self.vocab)
 
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer.get_vocab
     def get_vocab(self):
+        if self.subword_tokenizer_type == "sentencepiece":
+            vocab = {self.convert_ids_to_tokens(i): i for i in range(self.vocab_size)}
+            vocab.update(self.added_tokens_encoder)
+            return vocab
         return dict(self.vocab, **self.added_tokens_encoder)
 
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer._convert_token_to_id
     def _convert_token_to_id(self, token):
         """Converts a token (str) in an id using the vocab."""
+        if self.subword_tokenizer_type == "sentencepiece":
+            return self.subword_tokenizer.sp_model.PieceToId(token)
         return self.vocab.get(token, self.vocab.get(self.unk_token))
 
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer._convert_id_to_token
     def _convert_id_to_token(self, index):
         """Converts an index (integer) in a token (str) using the vocab."""
+        if self.subword_tokenizer_type == "sentencepiece":
+            return self.subword_tokenizer.sp_model.IdToPiece(index)
         return self.ids_to_tokens.get(index, self.unk_token)
 
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer.convert_tokens_to_string
     def convert_tokens_to_string(self, tokens):
         """Converts a sequence of tokens (string) in a single string."""
+        if self.subword_tokenizer_type == "sentencepiece":
+            return self.subword_tokenizer.sp_model.decode(tokens)
         out_string = " ".join(tokens).replace(" ##", "").strip()
         return out_string
 
@@ -360,16 +386,27 @@ class BertJapaneseTokenizer(PreTrainedTokenizer):
             return len(cls + token_ids_0 + sep) * [0]
         return len(cls + token_ids_0 + sep) * [0] + len(token_ids_1 + sep) * [1]
 
-    # Copied from transformers.models.bert.tokenization_bert.BertTokenizer.save_vocabulary
     def save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]:
-        index = 0
         if os.path.isdir(save_directory):
+            if self.subword_tokenizer_type == "sentencepiece":
                 vocab_file = os.path.join(
-                save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["vocab_file"]
+                    save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["spm_file"]
+                )
+            else:
+                vocab_file = os.path.join(
+                    save_directory,
+                    (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["vocab_file"],
                 )
         else:
             vocab_file = (filename_prefix + "-" if filename_prefix else "") + save_directory
+
+        if self.subword_tokenizer_type == "sentencepiece":
+            with open(vocab_file, "wb") as writer:
+                content_spiece_model = self.subword_tokenizer.sp_model.serialized_model_proto()
+                writer.write(content_spiece_model)
+        else:
             with open(vocab_file, "w", encoding="utf-8") as writer:
+                index = 0
                 for token, token_index in sorted(self.vocab.items(), key=lambda kv: kv[1]):
                     if index != token_index:
                         logger.warning(
@@ -893,3 +930,72 @@ class WordpieceTokenizer(object):
             else:
                 output_tokens.extend(sub_tokens)
         return output_tokens
+
+
+class SentencepieceTokenizer(object):
+    """
+    Runs sentencepiece tokenization. Based on transformers.models.albert.tokenization_albert.AlbertTokenizer.
+    """
+
+    def __init__(
+        self,
+        vocab,
+        unk_token,
+        do_lower_case=False,
+        remove_space=True,
+        keep_accents=True,
+        sp_model_kwargs: Optional[Dict[str, Any]] = None,
+    ):
+        self.vocab = vocab
+        self.unk_token = unk_token
+        self.do_lower_case = do_lower_case
+        self.remove_space = remove_space
+        self.keep_accents = keep_accents
+
+        self.sp_model_kwargs = {} if sp_model_kwargs is None else sp_model_kwargs
+        self.sp_model = spm.SentencePieceProcessor(**self.sp_model_kwargs)
+        self.sp_model.Load(self.vocab)
+
+    def preprocess_text(self, inputs):
+        if self.remove_space:
+            outputs = " ".join(inputs.strip().split())
+        else:
+            outputs = inputs
+        outputs = outputs.replace("``", '"').replace("''", '"')
+
+        if not self.keep_accents:
+            outputs = unicodedata.normalize("NFKD", outputs)
+            outputs = "".join([c for c in outputs if not unicodedata.combining(c)])
+        if self.do_lower_case:
+            outputs = outputs.lower()
+
+        return outputs
+
+    def tokenize(self, text):
+        """
+        Tokenizes text by sentencepiece. Based on [SentencePiece](https://github.com/google/sentencepiece).
+        Tokenization needs the given vocabulary.
+
+        Args:
+            text: A string needs to be tokenized.
+
+        Returns:
+            A list of sentencepiece tokens.
+        """
+        text = self.preprocess_text(text)
+        pieces = self.sp_model.encode(text, out_type=str)
+        new_pieces = []
+        for piece in pieces:
+            if len(piece) > 1 and piece[-1] == str(",") and piece[-2].isdigit():
+                cur_pieces = self.sp_model.EncodeAsPieces(piece[:-1].replace(SPIECE_UNDERLINE, ""))
+                if piece[0] != SPIECE_UNDERLINE and cur_pieces[0][0] == SPIECE_UNDERLINE:
+                    if len(cur_pieces[0]) == 1:
+                        cur_pieces = cur_pieces[1:]
+                    else:
+                        cur_pieces[0] = cur_pieces[0][1:]
+                cur_pieces.append(piece[-1])
+                new_pieces.extend(cur_pieces)
+            else:
+                new_pieces.append(piece)
+
+        return new_pieces

tests/models/bert_japanese/test_tokenization_bert_japanese.py

@@ -334,6 +334,16 @@ class BertJapaneseTokenizationTest(TokenizerTesterMixin, unittest.TestCase):
 
         self.assertListEqual(tokenizer.tokenize("こんばんは こんばんにちは こんにちは"), ["こん", "##ばんは", "[UNK]", "こんにちは"])
 
+    def test_sentencepiece_tokenizer(self):
+        tokenizer = BertJapaneseTokenizer.from_pretrained("nlp-waseda/roberta-base-japanese-with-auto-jumanpp")
+        subword_tokenizer = tokenizer.subword_tokenizer
+
+        tokens = subword_tokenizer.tokenize("国境 の 長い トンネル を 抜ける と 雪国 であった 。")
+        self.assertListEqual(tokens, ["▁国境", "▁の", "▁長い", "▁トンネル", "▁を", "▁抜ける", "▁と", "▁雪", "国", "▁であった", "▁。"])
+
+        tokens = subword_tokenizer.tokenize("こんばんは こんばん にち は こんにちは")
+        self.assertListEqual(tokens, ["▁こん", "ばん", "は", "▁こん", "ばん", "▁に", "ち", "▁は", "▁こんにちは"])
+
     def test_sequence_builders(self):
         tokenizer = self.tokenizer_class.from_pretrained("cl-tohoku/bert-base-japanese")