Various tokenizers fixes (#5558)

* BertTokenizerFast - Do not specify strip_accents by default

* Bump tokenizers to new version

* Add test for AddedToken serialization

setup.py

@@ -114,7 +114,7 @@ setup(
     packages=find_packages("src"),
     install_requires=[
         "numpy",
-        "tokenizers == 0.8.0-rc4",
+        "tokenizers == 0.8.1.rc1",
         # dataclasses for Python versions that don't have it
         "dataclasses;python_version<'3.7'",
         # utilities from PyPA to e.g. compare versions

src/transformers/tokenization_bert.py

@@ -606,7 +606,7 @@ class BertTokenizerFast(PreTrainedTokenizerFast):
         mask_token="[MASK]",
         clean_text=True,
         tokenize_chinese_chars=True,
-        strip_accents=True,
+        strip_accents=None,
         wordpieces_prefix="##",
         **kwargs
     ):

tests/test_tokenization_common.py

@@ -24,6 +24,7 @@ from typing import TYPE_CHECKING, Dict, List, Tuple, Union
 
 from transformers import PreTrainedTokenizer, PreTrainedTokenizerBase, PreTrainedTokenizerFast
 from transformers.testing_utils import require_tf, require_torch, slow
+from transformers.tokenization_utils import AddedToken
 
 
 if TYPE_CHECKING:
@@ -233,6 +234,12 @@ class TokenizerTesterMixin:
 
                 self.assertListEqual(subwords, subwords_loaded)
 
+    def test_pickle_added_tokens(self):
+        tok1 = AddedToken("<s>", rstrip=True, lstrip=True, normalized=False, single_word=True)
+        tok2 = pickle.loads(pickle.dumps(tok1))
+
+        self.assertEqual(tok1.__getstate__(), tok2.__getstate__())
+
     def test_added_tokens_do_lower_case(self):
         # TODO(thom) activate fast tokenizer tests once Rust tokenizers accepts white spaces in added tokens
         tokenizers = self.get_tokenizers(fast=False, do_lower_case=True)

tests/test_tokenization_fast.py

@@ -91,8 +91,6 @@ class CommonFastTokenizerTest(unittest.TestCase):
         self.assert_padding(tokenizer_r, tokenizer_p)
         self.assert_create_token_type_ids(tokenizer_r, tokenizer_p)
         self.assert_prepare_for_model(tokenizer_r, tokenizer_p)
-        # TODO: enable for v3.0.0
-        # self.assert_empty_output_no_special_tokens(tokenizer_r, tokenizer_p)
 
     def fast_only(self, tokenizer_r):
         # Ensure None raise an error
@@ -748,29 +746,41 @@ class WordPieceFastTokenizerTest(CommonFastTokenizerTest):
             add_special_tokens=True,
         )
 
-        expected_results = [
+        do_lower_case = tokenizer_r.init_kwargs.get("do_lower_case")
+        expected_results = (
+            [
+                ((0, 0), "[CLS]"),
                 ((0, 1), "A"),
                 ((1, 2), ","),
-            ((3, 8), "naive"),  # BERT normalizes this away
-            # Append MASK here after lower-casing
+                ((3, 5), "na"),
+                ((5, 6), "##ï"),
+                ((6, 8), "##ve"),
+                ((9, 15), "[MASK]"),
                 ((16, 21), "Allen"),
-            ((22, 24), "##NL"),
-            ((24, 25), "##P"),
-            ((26, 34), "sentence"),
-            ((35, 36), "."),
+                ((21, 23), "##NL"),
+                ((23, 24), "##P"),
+                ((25, 33), "sentence"),
+                ((33, 34), "."),
+                ((0, 0), "[SEP]"),
             ]
-
-        # Check if the tokenizer is uncased
-        if tokenizer_r.init_kwargs.get("do_lower_case"):
-            expected_results = [(offset, token.lower()) for (offset, token) in expected_results]
-
-        # Append the special tokens
-        expected_results.insert(3, ((9, 15), "[MASK]"))
-        expected_results.insert(0, (None, "[CLS]"))
-        expected_results.append((None, "[SEP]"))
+            if not do_lower_case
+            else [
+                ((0, 0), "[CLS]"),
+                ((0, 1), "a"),
+                ((1, 2), ","),
+                ((3, 8), "naive"),
+                ((9, 15), "[MASK]"),
+                ((16, 21), "allen"),
+                ((21, 23), "##nl"),
+                ((23, 24), "##p"),
+                ((25, 33), "sentence"),
+                ((33, 34), "."),
+                ((0, 0), "[SEP]"),
+            ]
+        )
 
         self.assertEqual([e[1] for e in expected_results], tokenizer_r.convert_ids_to_tokens(tokens["input_ids"]))
-        # self.assertEqual([e[0] for e in expected_results], tokens["offset_mapping"])
+        self.assertEqual([e[0] for e in expected_results], tokens["offset_mapping"])
 
 
 class RobertaFastTokenizerTest(CommonFastTokenizerTest):