tokenization abstract class - tests for examples

pytorch_transformers/tests/tokenization_openai_test.py

@@ -20,7 +20,7 @@ import json
 import shutil
 import pytest
 
-from pytorch_transformers.tokenization_openai import OpenAIGPTTokenizer, PRETRAINED_VOCAB_ARCHIVE_MAP
+from pytorch_transformers.tokenization_openai import OpenAIGPTTokenizer
 
 from.tokenization_tests_commons import create_and_check_tokenizer_commons
 
@@ -58,14 +58,6 @@ class OpenAIGPTTokenizationTest(unittest.TestCase):
         self.assertListEqual(
             tokenizer.convert_tokens_to_ids(input_tokens), input_bpe_tokens)
 
-    @pytest.mark.slow
-    def test_tokenizer_from_pretrained(self):
-        cache_dir = "/tmp/pytorch_transformers_test/"
-        for model_name in list(PRETRAINED_VOCAB_ARCHIVE_MAP.keys())[:1]:
-            tokenizer = OpenAIGPTTokenizer.from_pretrained(model_name, cache_dir=cache_dir)
-            shutil.rmtree(cache_dir)
-            self.assertIsNotNone(tokenizer)
-
 
 if __name__ == '__main__':
     unittest.main()

pytorch_transformers/tests/tokenization_transfo_xl_test.py

@@ -20,7 +20,7 @@ from io import open
 import shutil
 import pytest
 
-from pytorch_transformers.tokenization_transfo_xl import TransfoXLTokenizer, PRETRAINED_VOCAB_ARCHIVE_MAP
+from pytorch_transformers.tokenization_transfo_xl import TransfoXLTokenizer
 
 from.tokenization_tests_commons import create_and_check_tokenizer_commons
 
@@ -59,13 +59,6 @@ class TransfoXLTokenizationTest(unittest.TestCase):
             tokenizer.tokenize(u" \tHeLLo ! how  \n Are yoU ?  "),
             ["HeLLo", "!", "how", "Are", "yoU", "?"])
 
-    @pytest.mark.slow
-    def test_tokenizer_from_pretrained(self):
-        cache_dir = "/tmp/pytorch_transformers_test/"
-        for model_name in list(PRETRAINED_VOCAB_ARCHIVE_MAP.keys())[:1]:
-            tokenizer = TransfoXLTokenizer.from_pretrained(model_name, cache_dir=cache_dir)
-            shutil.rmtree(cache_dir)
-            self.assertIsNotNone(tokenizer)
 
 if __name__ == '__main__':
     unittest.main()

pytorch_transformers/tests/tokenization_utils_test.py

+# coding=utf-8
+# Copyright 2018 HuggingFace Inc..
+#
+# 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.
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import unittest
+
+from pytorch_transformers import PreTrainedTokenizer
+from pytorch_transformers.tokenization_gpt2 import GPT2Tokenizer
+
+class TokenizerUtilsTest(unittest.TestCase):
+    def check_tokenizer_from_pretrained(self, tokenizer_class):
+        s3_models = list(tokenizer_class.max_model_input_sizes.keys())
+        for model_name in s3_models[:1]:
+            tokenizer = tokenizer_class.from_pretrained(model_name)
+            self.assertIsNotNone(tokenizer)
+            self.assertIsInstance(tokenizer, PreTrainedTokenizer)
+
+    def test_pretrained_tokenizers(self):
+        self.check_tokenizer_from_pretrained(GPT2Tokenizer)
+
+if __name__ == "__main__":
+    unittest.main()

pytorch_transformers/tests/tokenization_xlm_test.py

@@ -20,9 +20,9 @@ import json
 import shutil
 import pytest
 
-from pytorch_transformers.tokenization_xlm import XLMTokenizer, PRETRAINED_VOCAB_ARCHIVE_MAP
+from pytorch_transformers.tokenization_xlm import XLMTokenizer
 
-from.tokenization_tests_commons import create_and_check_tokenizer_commons
+from .tokenization_tests_commons import create_and_check_tokenizer_commons
 
 class XLMTokenizationTest(unittest.TestCase):
 
@@ -57,14 +57,6 @@ class XLMTokenizationTest(unittest.TestCase):
         self.assertListEqual(
             tokenizer.convert_tokens_to_ids(input_tokens), input_bpe_tokens)
 
-    @pytest.mark.slow
-    def test_tokenizer_from_pretrained(self):
-        cache_dir = "/tmp/pytorch_transformers_test/"
-        for model_name in list(PRETRAINED_VOCAB_ARCHIVE_MAP.keys())[:1]:
-            tokenizer = XLMTokenizer.from_pretrained(model_name, cache_dir=cache_dir)
-            shutil.rmtree(cache_dir)
-            self.assertIsNotNone(tokenizer)
-
 
 if __name__ == '__main__':
     unittest.main()

pytorch_transformers/tests/tokenization_xlnet_test.py

@@ -19,9 +19,7 @@ import unittest
 import shutil
 import pytest
 
-from pytorch_transformers.tokenization_xlnet import (XLNetTokenizer,
-                                                        PRETRAINED_VOCAB_ARCHIVE_MAP,
-                                                        SPIECE_UNDERLINE)
+from pytorch_transformers.tokenization_xlnet import (XLNetTokenizer, SPIECE_UNDERLINE)
 
 from.tokenization_tests_commons import create_and_check_tokenizer_commons
 
@@ -60,14 +58,6 @@ class XLNetTokenizationTest(unittest.TestCase):
                                            SPIECE_UNDERLINE + u'is', SPIECE_UNDERLINE + u'f', u'al', u's',
                                            u'<unk>', u'.'])
 
-    @pytest.mark.slow
-    def test_tokenizer_from_pretrained(self):
-        cache_dir = "/tmp/pytorch_transformers_test/"
-        for model_name in list(PRETRAINED_VOCAB_ARCHIVE_MAP.keys())[:1]:
-            tokenizer = XLNetTokenizer.from_pretrained(model_name, cache_dir=cache_dir)
-            shutil.rmtree(cache_dir)
-            self.assertIsNotNone(tokenizer)
-
     def test_tokenizer_lower(self):
         tokenizer = XLNetTokenizer(SAMPLE_VOCAB, do_lower_case=True)
         tokens = tokenizer.tokenize(u"I was born in 92000, and this is falsé.")

pytorch_transformers/tokenization_bert.py

@@ -23,11 +23,15 @@ import unicodedata
 from io import open
 
 from .file_utils import cached_path
-from .model_utils import clean_up_tokenization
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
+VOCAB_FILES_NAMES = {'vocab_file': 'vocab.txt'}
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'vocab_file':
+    {
     'bert-base-uncased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-uncased-vocab.txt",
     'bert-large-uncased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-large-uncased-vocab.txt",
     'bert-base-cased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-cased-vocab.txt",
@@ -41,8 +45,9 @@ PRETRAINED_VOCAB_ARCHIVE_MAP = {
     'bert-large-uncased-whole-word-masking-finetuned-squad': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-large-uncased-whole-word-masking-finetuned-squad-vocab.txt",
     'bert-large-cased-whole-word-masking-finetuned-squad': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-large-cased-whole-word-masking-finetuned-squad-vocab.txt",
     'bert-base-cased-finetuned-mrpc': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-cased-finetuned-mrpc-vocab.txt",
-}
-PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP = {
+}}
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
     'bert-base-uncased': 512,
     'bert-large-uncased': 512,
     'bert-base-cased': 512,
@@ -57,7 +62,6 @@ PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP = {
     'bert-large-cased-whole-word-masking-finetuned-squad': 512,
     'bert-base-cased-finetuned-mrpc': 512,
 }
-VOCAB_NAME = 'vocab.txt'
 
 def load_vocab(vocab_file):
     """Loads a vocabulary file into a dictionary."""
@@ -83,8 +87,11 @@ def whitespace_tokenize(text):
     return tokens
 
 
-class BertTokenizer(object):
+class BertTokenizer(PreTrainedTokenizer):
     """Runs end-to-end tokenization: punctuation splitting + wordpiece"""
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
     def __init__(self, vocab_file, do_lower_case=True, max_len=None, do_basic_tokenize=True,
                  never_split=("[UNK]", "[SEP]", "[PAD]", "[CLS]", "[MASK]")):
@@ -203,7 +210,7 @@ class BertTokenizer(object):
         """Save the tokenizer vocabulary to a directory or file."""
         index = 0
         if os.path.isdir(vocab_path):
-            vocab_file = os.path.join(vocab_path, VOCAB_NAME)
+            vocab_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['vocab_file'])
         with open(vocab_file, "w", encoding="utf-8") as writer:
             for token, token_index in sorted(self.vocab.items(), key=lambda kv: kv[1]):
                 if index != token_index:
@@ -215,13 +222,10 @@ class BertTokenizer(object):
         return (vocab_file,)
 
     @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a PreTrainedBertModel from a pre-trained model file.
-        Download and cache the pre-trained model file if needed.
+    def from_pretrained(cls, pretrained_model_name_or_path, *inputs, **kwargs):
+        """ Instantiate a BertTokenizer from pre-trained vocabulary files.
         """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
+        if pretrained_model_name_or_path in PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES:
             if '-cased' in pretrained_model_name_or_path and kwargs.get('do_lower_case', True):
                 logger.warning("The pre-trained model you are loading is a cased model but you have not set "
                                "`do_lower_case` to False. We are setting `do_lower_case=False` for you but "
@@ -232,40 +236,8 @@ class BertTokenizer(object):
                                "`do_lower_case` to False. We are setting `do_lower_case=True` for you "
                                "but you may want to check this behavior.")
                 kwargs['do_lower_case'] = True
-        else:
-            vocab_file = pretrained_model_name_or_path
-        if os.path.isdir(vocab_file):
-            vocab_file = os.path.join(vocab_file, VOCAB_NAME)
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find any file "
-                    "associated to this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        vocab_file))
-            return None
-        if resolved_vocab_file == vocab_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP:
-            # if we're using a pretrained model, ensure the tokenizer wont index sequences longer
-            # than the number of positional embeddings
-            max_len = PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP[pretrained_model_name_or_path]
-            kwargs['max_len'] = min(kwargs.get('max_len', int(1e12)), max_len)
-        # Instantiate tokenizer.
-        tokenizer = cls(resolved_vocab_file, *inputs, **kwargs)
-        return tokenizer
+
+        return super(BertTokenizer, cls)._from_pretrained(pretrained_model_name_or_path, *inputs, **kwargs)
 
 
 class BasicTokenizer(object):

pytorch_transformers/tokenization_gpt2.py

@@ -23,8 +23,6 @@ import os
 import regex as re
 from io import open
 
-from .model_utils import clean_up_tokenization
-
 try:
     from functools import lru_cache
 except ImportError:
@@ -33,24 +31,38 @@ except ImportError:
     def lru_cache():
         return lambda func: func
 
-from .file_utils import cached_path
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
-    'gpt2': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-vocab.json",
-    'gpt2-medium': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-medium-vocab.json",
+VOCAB_FILES_NAMES = {
+    'vocab_file': 'vocab.json',
+    'merges_file': 'merges.txt',
+    'special_tokens_file': 'special_tokens.txt'
 }
-PRETRAINED_MERGES_ARCHIVE_MAP = {
-    'gpt2': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-merges.txt",
-    'gpt2-medium': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-medium-merges.txt",
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'vocab_file':
+    {
+        'gpt2': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-vocab.json",
+        'gpt2-medium': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-medium-vocab.json",
+    },
+    'merges_file':
+    {
+        'gpt2': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-merges.txt",
+        'gpt2-medium': "https://s3.amazonaws.com/models.huggingface.co/bert/gpt2-medium-merges.txt",
+    },
+    'special_tokens_file':
+    {
+        'gpt2': None,
+        'gpt2-medium': None,
+    }
 }
-PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP = {
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
     'gpt2': 1024,
+    'gpt2-medium': 1024,
 }
-VOCAB_NAME = 'vocab.json'
-MERGES_NAME = 'merges.txt'
-SPECIAL_TOKENS_NAME = 'special_tokens.txt'
 
 @lru_cache()
 def bytes_to_unicode():
@@ -87,70 +99,16 @@ def get_pairs(word):
         prev_char = char
     return pairs
 
-class GPT2Tokenizer(object):
+class GPT2Tokenizer(PreTrainedTokenizer):
     """
     GPT-2 BPE tokenizer. Peculiarities:
         - Byte-level BPE
     """
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a GPT2Tokenizer from a pre-trained model file.
-        Download and cache the pre-trained model file if needed.
-        """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
-            merges_file = PRETRAINED_MERGES_ARCHIVE_MAP[pretrained_model_name_or_path]
-            special_tokens_file = None
-        else:
-            vocab_file = os.path.join(pretrained_model_name_or_path, VOCAB_NAME)
-            merges_file = os.path.join(pretrained_model_name_or_path, MERGES_NAME)
-            special_tokens_file = os.path.join(pretrained_model_name_or_path, SPECIAL_TOKENS_NAME)
-            if not os.path.exists(special_tokens_file):
-                special_tokens_file = None
-            else:
-                logger.info("loading special tokens file {}".format(special_tokens_file))
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-            resolved_merges_file = cached_path(merges_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find files {} and {} "
-                    "at this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        pretrained_model_name_or_path,
-                        vocab_file, merges_file))
-            return None
-        if resolved_vocab_file == vocab_file and resolved_merges_file == merges_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-            logger.info("loading merges file {}".format(merges_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-            logger.info("loading merges file {} from cache at {}".format(
-                merges_file, resolved_merges_file))
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP:
-            # if we're using a pretrained model, ensure the tokenizer wont index sequences longer
-            # than the number of positional embeddings
-            max_len = PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP[pretrained_model_name_or_path]
-            kwargs['max_len'] = min(kwargs.get('max_len', int(1e12)), max_len)
-        # Instantiate tokenizer.
-        if special_tokens_file and 'special_tokens' not in kwargs:
-            special_tokens = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
-        else:
-            special_tokens = kwargs.pop('special_tokens', [])
-        tokenizer = cls(resolved_vocab_file, resolved_merges_file, special_tokens=special_tokens, *inputs, **kwargs)
-        return tokenizer
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
-    def __init__(self, vocab_file, merges_file, errors='replace', special_tokens=None, max_len=None):
+    def __init__(self, vocab_file, merges_file, special_tokens_file=None, special_tokens=None, errors='replace', max_len=None):
         self.max_len = max_len if max_len is not None else int(1e12)
         self.encoder = json.load(open(vocab_file))
         self.decoder = {v:k for k,v in self.encoder.items()}
@@ -165,9 +123,16 @@ class GPT2Tokenizer(object):
         # Should haved added re.IGNORECASE so BPE merges can happen for capitalized versions of contractions
         self.pat = re.compile(r"""'s|'t|'re|'ve|'m|'ll|'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+""")
 
+        all_special_tokens = []
+        if special_tokens_file is not None:
+            special_tokens_to_add = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
+            all_special_tokens.extend(special_tokens_to_add)
+        if special_tokens is not None and special_tokens:
+            all_special_tokens.extend(special_tokens)
+
         self.special_tokens = {}
         self.special_tokens_decoder = {}
-        self.set_special_tokens(special_tokens)
+        self.set_special_tokens(all_special_tokens)
 
     def __len__(self):
         return len(self.encoder) + len(self.special_tokens)
@@ -285,9 +250,9 @@ class GPT2Tokenizer(object):
         if not os.path.isdir(vocab_path):
             logger.error("Vocabulary path ({}) should be a directory".format(vocab_path))
             return
-        vocab_file = os.path.join(vocab_path, VOCAB_NAME)
-        merge_file = os.path.join(vocab_path, MERGES_NAME)
-        special_tokens_file = os.path.join(vocab_path, SPECIAL_TOKENS_NAME)
+        vocab_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['vocab_file'])
+        merge_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['merges_file'])
+        special_tokens_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['special_tokens_file'])
 
         with open(vocab_file, 'w', encoding='utf-8') as f:
             f.write(json.dumps(self.encoder, ensure_ascii=False))

pytorch_transformers/tokenization_openai.py

@@ -26,23 +26,35 @@ from io import open
 from tqdm import tqdm
 
 from .file_utils import cached_path
-from .model_utils import clean_up_tokenization
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 from .tokenization_bert import BasicTokenizer
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
-    'openai-gpt': "https://s3.amazonaws.com/models.huggingface.co/bert/openai-gpt-vocab.json",
+VOCAB_FILES_NAMES = {
+    'vocab_file': 'vocab.json',
+    'merges_file': 'merges.txt',
+    'special_tokens_file': 'special_tokens.txt'
 }
-PRETRAINED_MERGES_ARCHIVE_MAP = {
-    'openai-gpt': "https://s3.amazonaws.com/models.huggingface.co/bert/openai-gpt-merges.txt",
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'vocab_file':
+    {
+        'openai-gpt': "https://s3.amazonaws.com/models.huggingface.co/bert/openai-gpt-vocab.json",
+    },
+    'merges_file':
+    {
+        'openai-gpt': "https://s3.amazonaws.com/models.huggingface.co/bert/openai-gpt-merges.txt",
+    },
+    'special_tokens_file':
+    {
+        'openai-gpt': None,
+    }
 }
-PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP = {
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
     'openai-gpt': 512,
 }
-VOCAB_NAME = 'vocab.json'
-MERGES_NAME = 'merges.txt'
-SPECIAL_TOKENS_NAME = 'special_tokens.txt'
 
 def get_pairs(word):
     """
@@ -71,7 +83,7 @@ def text_standardize(text):
     text = re.sub(r'[^\S\n]+', ' ', text)
     return text.strip()
 
-class OpenAIGPTTokenizer(object):
+class OpenAIGPTTokenizer(PreTrainedTokenizer):
     """
     BPE tokenizer. Peculiarities:
         - lower case all inputs
@@ -79,65 +91,11 @@ class OpenAIGPTTokenizer(object):
         - argument special_tokens and function set_special_tokens:
             can be used to add additional symbols (ex: "__classify__") to a vocabulary.
     """
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a PreTrainedBertModel from a pre-trained model file.
-        Download and cache the pre-trained model file if needed.
-        """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
-            merges_file = PRETRAINED_MERGES_ARCHIVE_MAP[pretrained_model_name_or_path]
-            special_tokens_file = None
-        else:
-            vocab_file = os.path.join(pretrained_model_name_or_path, VOCAB_NAME)
-            merges_file = os.path.join(pretrained_model_name_or_path, MERGES_NAME)
-            special_tokens_file = os.path.join(pretrained_model_name_or_path, SPECIAL_TOKENS_NAME)
-            if not os.path.exists(special_tokens_file):
-                special_tokens_file = None
-            else:
-                logger.info("loading special tokens file {}".format(special_tokens_file))
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-            resolved_merges_file = cached_path(merges_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find files {} and {} "
-                    "at this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        pretrained_model_name_or_path,
-                        vocab_file, merges_file))
-            return None
-        if resolved_vocab_file == vocab_file and resolved_merges_file == merges_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-            logger.info("loading merges file {}".format(merges_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-            logger.info("loading merges file {} from cache at {}".format(
-                merges_file, resolved_merges_file))
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP:
-            # if we're using a pretrained model, ensure the tokenizer wont index sequences longer
-            # than the number of positional embeddings
-            max_len = PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP[pretrained_model_name_or_path]
-            kwargs['max_len'] = min(kwargs.get('max_len', int(1e12)), max_len)
-        # Instantiate tokenizer.
-        if special_tokens_file and 'special_tokens' not in kwargs:
-            special_tokens = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
-        else:
-            special_tokens = kwargs.pop('special_tokens', [])
-        tokenizer = cls(resolved_vocab_file, resolved_merges_file, special_tokens=special_tokens, *inputs, **kwargs)
-        return tokenizer
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
-    def __init__(self, vocab_file, merges_file, special_tokens=None, max_len=None):
+    def __init__(self, vocab_file, merges_file, special_tokens_file=None, special_tokens=None, max_len=None):
         try:
             import ftfy
             import spacy
@@ -156,9 +114,17 @@ class OpenAIGPTTokenizer(object):
         merges = [tuple(merge.split()) for merge in merges]
         self.bpe_ranks = dict(zip(merges, range(len(merges))))
         self.cache = {}
+
+        all_special_tokens = []
+        if special_tokens_file is not None:
+            special_tokens_to_add = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
+            all_special_tokens.extend(special_tokens_to_add)
+        if special_tokens is not None and special_tokens:
+            all_special_tokens.extend(special_tokens)
+
         self.special_tokens = {}
         self.special_tokens_decoder = {}
-        self.set_special_tokens(special_tokens)
+        self.set_special_tokens(all_special_tokens)
 
     def __len__(self):
         return len(self.encoder) + len(self.special_tokens)
@@ -286,9 +252,9 @@ class OpenAIGPTTokenizer(object):
         if not os.path.isdir(vocab_path):
             logger.error("Vocabulary path ({}) should be a directory".format(vocab_path))
             return
-        vocab_file = os.path.join(vocab_path, VOCAB_NAME)
-        merge_file = os.path.join(vocab_path, MERGES_NAME)
-        special_tokens_file = os.path.join(vocab_path, SPECIAL_TOKENS_NAME)
+        vocab_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['vocab_file'])
+        merge_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['merges_file'])
+        special_tokens_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['special_tokens_file'])
 
         with open(vocab_file, 'w', encoding='utf-8') as f:
             f.write(json.dumps(self.encoder, ensure_ascii=False))

pytorch_transformers/tokenization_transfo_xl.py

@@ -31,7 +31,7 @@ import torch
 import numpy as np
 
 from .file_utils import cached_path
-from .model_utils import clean_up_tokenization
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 
 if sys.version_info[0] == 2:
     import cPickle as pickle
@@ -41,66 +41,35 @@ else:
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
-    'transfo-xl-wt103': "https://s3.amazonaws.com/models.huggingface.co/bert/transfo-xl-wt103-vocab.bin",
+VOCAB_FILES_NAMES = {'pretrained_vocab_file': 'vocab.bin'}
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'pretrained_vocab_file':
+    {
+        'transfo-xl-wt103': "https://s3.amazonaws.com/models.huggingface.co/bert/transfo-xl-wt103-vocab.bin",
+    }
+}
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
+    'transfo-xl-wt103': 512,
 }
-VOCAB_NAME = 'vocab.bin'
 
 PRETRAINED_CORPUS_ARCHIVE_MAP = {
     'transfo-xl-wt103': "https://s3.amazonaws.com/models.huggingface.co/bert/transfo-xl-wt103-corpus.bin",
 }
 CORPUS_NAME = 'corpus.bin'
 
-class TransfoXLTokenizer(object):
+class TransfoXLTokenizer(PreTrainedTokenizer):
     """
     Transformer-XL tokenizer adapted from Vocab class in https://github.com/kimiyoung/transformer-xl
     """
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a TransfoXLTokenizer.
-        The TransfoXLTokenizer.
-        """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
-        else:
-            if os.path.isdir(pretrained_model_name_or_path):
-                vocab_file = os.path.join(pretrained_model_name_or_path, VOCAB_NAME)
-            else:
-                vocab_file = pretrained_model_name_or_path
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find files {} "
-                    "at this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        pretrained_model_name_or_path,
-                        vocab_file))
-            return None
-        if resolved_vocab_file == vocab_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-
-        # Instantiate tokenizer.
-        tokenizer = cls(*inputs, **kwargs)
-        vocab_dict = torch.load(resolved_vocab_file)
-        for key, value in vocab_dict.items():
-            tokenizer.__dict__[key] = value
-        return tokenizer
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
     def __init__(self, special=[], min_freq=0, max_size=None, lower_case=False,
-                 delimiter=None, vocab_file=None, never_split=("<unk>", "<eos>", "<formula>")):
+                 delimiter=None, vocab_file=None, pretrained_vocab_file=None,
+                 never_split=("<unk>", "<eos>", "<formula>")):
         self.counter = Counter()
         self.special = special
         self.min_freq = min_freq
@@ -110,6 +79,13 @@ class TransfoXLTokenizer(object):
         self.vocab_file = vocab_file
         self.never_split = never_split
 
+        if pretrained_vocab_file is not None:
+            # Hack because, honestly this tokenizer was not made to be used
+            # in a library like ours, at all.
+            vocab_dict = torch.load(pretrained_vocab_file)
+            for key, value in vocab_dict.items():
+                self.__dict__[key] = value
+
         if vocab_file is not None:
             self.build_vocab()
 
@@ -157,7 +133,7 @@ class TransfoXLTokenizer(object):
         """Save the tokenizer vocabulary to a directory or file."""
         index = 0
         if os.path.isdir(vocab_path):
-            vocab_file = os.path.join(vocab_path, VOCAB_NAME)
+            vocab_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['pretrained_vocab_file'])
         torch.save(self.__dict__, vocab_file)
         return (vocab_file,)
 
@@ -484,7 +460,7 @@ class TransfoXLCorpus(object):
                 "We assumed '{}' was a path or url but couldn't find files {} "
                 "at this path or url.".format(
                     pretrained_model_name_or_path,
-                    ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
+                    ', '.join(PRETRAINED_CORPUS_ARCHIVE_MAP.keys()),
                     pretrained_model_name_or_path,
                     corpus_file))
             return None

pytorch_transformers/tokenization_utils.py

+# coding=utf-8
+# Copyright 2018 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 OpenAI GPT."""
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+import sys
+import json
+import logging
+import os
+import regex as re
+from io import open
+
+try:
+    from functools import lru_cache
+except ImportError:
+    # Just a dummy decorator to get the checks to run on python2
+    # because honestly I don't want to support a byte-level unicode BPE tokenizer on python 2 right now.
+    def lru_cache():
+        return lambda func: func
+
+from .file_utils import cached_path
+
+logger = logging.getLogger(__name__)
+
+
+class PreTrainedTokenizer(object):
+    """ An abstract class to handle dowloading and loading pretrained tokenizers.
+    """
+    vocab_files_names = {}
+    pretrained_vocab_files_map = {}
+    max_model_input_sizes = {}
+
+    @classmethod
+    def from_pretrained(cls, *inputs, **kwargs):
+        return cls._from_pretrained(*inputs, **kwargs)
+
+    @classmethod
+    def _from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
+        """
+        Instantiate a PreTrainedTokenizer from pre-trained vocabulary files.
+        Download and cache the vocabulary files if needed.
+        """
+        s3_models = list(cls.max_model_input_sizes.keys())
+        vocab_files = {}
+        if pretrained_model_name_or_path in s3_models:
+            for file_id, map_list in cls.pretrained_vocab_files_map.items():
+                vocab_files[file_id] = map_list[pretrained_model_name_or_path]
+        else:
+            for file_id, file_name in cls.vocab_files_names.items():
+                if os.path.isdir(pretrained_model_name_or_path):
+                    full_file_name = os.path.join(pretrained_model_name_or_path, file_name)
+                else:
+                    full_file_name = pretrained_model_name_or_path
+                if not os.path.exists(full_file_name):
+                    logger.info("Didn't find file {}. We don't load it.".format(full_file_name))
+                    full_file_name = None
+                vocab_files[file_id] = full_file_name
+        # redirect to the cache, if necessary
+        try:
+            resolved_vocab_files = {}
+            for file_id, file_path in vocab_files.items():
+                if file_path is None:
+                    resolved_vocab_files[file_id] = None
+                else:
+                    resolved_vocab_files[file_id] = cached_path(file_path, cache_dir=cache_dir)
+        except EnvironmentError:
+            if pretrained_model_name_or_path in s3_models:
+                logger.error("Couldn't reach server to download vocabulary.")
+            else:
+                logger.error(
+                    "Model name '{}' was not found in model name list ({}). "
+                    "We assumed '{}' was a path or url but couldn't find files {} "
+                    "at this path or url.".format(
+                        pretrained_model_name_or_path, ', '.join(s3_models),
+                        pretrained_model_name_or_path, str(vocab_files.keys())))
+            return None
+
+        for file_id, file_path in vocab_files.items():
+            if file_path == resolved_vocab_files[file_id]:
+                logger.info("loading file {}".format(file_path))
+            else:
+                logger.info("loading file {} from cache at {}".format(
+                    file_path, resolved_vocab_files[file_id]))
+
+        if pretrained_model_name_or_path in cls.max_model_input_sizes:
+            # if we're using a pretrained model, ensure the tokenizer
+            # wont index sequences longer than the number of positional embeddings
+            max_len = cls.max_model_input_sizes[pretrained_model_name_or_path]
+            kwargs['max_len'] = min(kwargs.get('max_len', int(1e12)), max_len)
+
+        # Instantiate tokenizer.
+        tokenizer = cls(*inputs, **resolved_vocab_files, **kwargs)
+
+        return tokenizer
+
+
+def clean_up_tokenization(out_string):
+    out_string.replace(' .', '.').replace(' ?', '?').replace(' !', '!').replace(' ,', ','
+                    ).replace(" ' ", "'").replace(" n't", "n't").replace(" 'm", "'m").replace(" do not", " don't"
+                    ).replace(" 's", "'s").replace(" 've", "'ve").replace(" 're", "'re")
+    return out_string

pytorch_transformers/tokenization_xlm.py

@@ -26,30 +26,42 @@ from io import open
 from tqdm import tqdm
 
 from .file_utils import cached_path
-from .model_utils import clean_up_tokenization
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 from .tokenization_bert import BasicTokenizer
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
-    'xlm-mlm-en-2048': "https://s3.amazonaws.com/models.huggingface.co/bert/xlm-mlm-en-2048-vocab.json",
+VOCAB_FILES_NAMES = {
+    'vocab_file': 'vocab.json',
+    'merges_file': 'merges.txt',
+    'special_tokens_file': 'special_tokens.txt'
 }
-PRETRAINED_MERGES_ARCHIVE_MAP = {
-    'xlm-mlm-en-2048': "https://s3.amazonaws.com/models.huggingface.co/bert/xlm-mlm-en-2048-merges.txt",
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'vocab_file':
+    {
+        'xlm-mlm-en-2048': "https://s3.amazonaws.com/models.huggingface.co/bert/xlm-mlm-en-2048-vocab.json",
+    },
+    'merges_file':
+    {
+        'xlm-mlm-en-2048': "https://s3.amazonaws.com/models.huggingface.co/bert/xlm-mlm-en-2048-merges.txt",
+    },
+    'special_tokens_file':
+    {
+        'xlm-mlm-en-2048': None,
+    }
 }
-PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP = {
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
     'xlm-mlm-en-2048': 512,
 }
-VOCAB_NAME = 'vocab.json'
-MERGES_NAME = 'merges.txt'
-SPECIAL_TOKENS_NAME = 'special_tokens.txt'
 
-INDEX= {
-  "bos_index": 0,
-  "eos_index": 1,
-  "pad_index": 2,
-  "unk_index": 3,
-  "mask_index": 5
+INDEX = {
+    "bos_index": 0,
+    "eos_index": 1,
+    "pad_index": 2,
+    "unk_index": 3,
+    "mask_index": 5
 }
 
 def get_pairs(word):
@@ -79,7 +91,7 @@ def text_standardize(text):
     text = re.sub(r'[^\S\n]+', ' ', text)
     return text.strip()
 
-class XLMTokenizer(object):
+class XLMTokenizer(PreTrainedTokenizer):
     """
     BPE tokenizer for XLM, adapted from OpenAI BPE tokenizer. Peculiarities:
         - lower case all inputs
@@ -87,65 +99,11 @@ class XLMTokenizer(object):
         - argument special_tokens and function set_special_tokens:
             can be used to add additional symbols (ex: "__classify__") to a vocabulary.
     """
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a PreTrainedBertModel from a pre-trained model file.
-        Download and cache the pre-trained model file if needed.
-        """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
-            merges_file = PRETRAINED_MERGES_ARCHIVE_MAP[pretrained_model_name_or_path]
-            special_tokens_file = None
-        else:
-            vocab_file = os.path.join(pretrained_model_name_or_path, VOCAB_NAME)
-            merges_file = os.path.join(pretrained_model_name_or_path, MERGES_NAME)
-            special_tokens_file = os.path.join(pretrained_model_name_or_path, SPECIAL_TOKENS_NAME)
-            if not os.path.exists(special_tokens_file):
-                special_tokens_file = None
-            else:
-                logger.info("loading special tokens file {}".format(special_tokens_file))
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-            resolved_merges_file = cached_path(merges_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find files {} and {} "
-                    "at this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        pretrained_model_name_or_path,
-                        vocab_file, merges_file))
-            return None
-        if resolved_vocab_file == vocab_file and resolved_merges_file == merges_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-            logger.info("loading merges file {}".format(merges_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-            logger.info("loading merges file {} from cache at {}".format(
-                merges_file, resolved_merges_file))
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP:
-            # if we're using a pretrained model, ensure the tokenizer wont index sequences longer
-            # than the number of positional embeddings
-            max_len = PRETRAINED_VOCAB_POSITIONAL_EMBEDDINGS_SIZE_MAP[pretrained_model_name_or_path]
-            kwargs['max_len'] = min(kwargs.get('max_len', int(1e12)), max_len)
-        # Instantiate tokenizer.
-        if special_tokens_file and 'special_tokens' not in kwargs:
-            special_tokens = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
-        else:
-            special_tokens = kwargs.pop('special_tokens', [])
-        tokenizer = cls(resolved_vocab_file, resolved_merges_file, special_tokens=special_tokens, *inputs, **kwargs)
-        return tokenizer
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
-    def __init__(self, vocab_file, merges_file, special_tokens=None, max_len=None):
+    def __init__(self, vocab_file, merges_file, special_tokens_file=None, special_tokens=None, max_len=None):
         try:
             import ftfy
             import spacy
@@ -164,9 +122,17 @@ class XLMTokenizer(object):
         merges = [tuple(merge.split()[:2]) for merge in merges]
         self.bpe_ranks = dict(zip(merges, range(len(merges))))
         self.cache = {}
+
+        all_special_tokens = []
+        if special_tokens_file is not None:
+            special_tokens_to_add = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
+            all_special_tokens.extend(special_tokens_to_add)
+        if special_tokens is not None and special_tokens:
+            all_special_tokens.extend(special_tokens)
+
         self.special_tokens = {}
         self.special_tokens_decoder = {}
-        self.set_special_tokens(special_tokens)
+        self.set_special_tokens(all_special_tokens)
 
     def __len__(self):
         return len(self.encoder) + len(self.special_tokens)
@@ -294,9 +260,9 @@ class XLMTokenizer(object):
         if not os.path.isdir(vocab_path):
             logger.error("Vocabulary path ({}) should be a directory".format(vocab_path))
             return
-        vocab_file = os.path.join(vocab_path, VOCAB_NAME)
-        merge_file = os.path.join(vocab_path, MERGES_NAME)
-        special_tokens_file = os.path.join(vocab_path, SPECIAL_TOKENS_NAME)
+        vocab_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['vocab_file'])
+        merge_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['merges_file'])
+        special_tokens_file = os.path.join(vocab_path, VOCAB_FILES_NAMES['special_tokens_file'])
 
         with open(vocab_file, 'w', encoding='utf-8') as f:
             f.write(json.dumps(self.encoder, ensure_ascii=False))

pytorch_transformers/tokenization_xlnet.py

@@ -27,15 +27,24 @@ import unicodedata
 import six
 
 from .file_utils import cached_path
-from .model_utils import clean_up_tokenization
+from .tokenization_utils import PreTrainedTokenizer, clean_up_tokenization
 
 logger = logging.getLogger(__name__)
 
-PRETRAINED_VOCAB_ARCHIVE_MAP = {
+VOCAB_FILES_NAMES = {'vocab_file': 'spiece.model'}
+
+PRETRAINED_VOCAB_FILES_MAP = {
+    'vocab_file':
+    {
     'xlnet-large-cased': "https://s3.amazonaws.com/models.huggingface.co/bert/xlnet-large-cased-spiece.model",
+    }
 }
+
+PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES = {
+    'xlnet-large-cased': 512,
+}
+
 VOCAB_NAME = 'spiece.model'
-SPECIAL_TOKENS_NAME = 'special_tokens.txt'
 
 SPIECE_UNDERLINE = u'▁'
 
@@ -46,7 +55,7 @@ SEG_ID_CLS = 2
 SEG_ID_SEP = 3
 SEG_ID_PAD = 4
 
-class XLNetTokenizer(object):
+class XLNetTokenizer(PreTrainedTokenizer):
     """
         SentencePiece based tokenizer. Peculiarities:
             - requires SentencePiece: https://github.com/google/sentencepiece
@@ -63,64 +72,11 @@ class XLNetTokenizer(object):
         "<eod>"  : 7,
         "<eop>"  : 8,
     }
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name_or_path, cache_dir=None, *inputs, **kwargs):
-        """
-        Instantiate a PreTrainedBertModel from a pre-trained model file.
-        Download and cache the pre-trained model file if needed.
-        """
-        if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-            vocab_file = PRETRAINED_VOCAB_ARCHIVE_MAP[pretrained_model_name_or_path]
-            special_tokens_file = None
-            if '-cased' in pretrained_model_name_or_path and kwargs.get('do_lower_case', True):
-                logger.warning("The pre-trained model you are loading is a cased model but you have not set "
-                               "`do_lower_case` to False. We are setting `do_lower_case=False` for you but "
-                               "you may want to check this behavior.")
-                kwargs['do_lower_case'] = False
-            elif '-cased' not in pretrained_model_name_or_path and not kwargs.get('do_lower_case', True):
-                logger.warning("The pre-trained model you are loading is an uncased model but you have set "
-                               "`do_lower_case` to False. We are setting `do_lower_case=True` for you "
-                               "but you may want to check this behavior.")
-                kwargs['do_lower_case'] = True
-        else:
-            vocab_file = os.path.join(pretrained_model_name_or_path, VOCAB_NAME)
-            special_tokens_file = os.path.join(pretrained_model_name_or_path, SPECIAL_TOKENS_NAME)
-            if not os.path.exists(special_tokens_file):
-                special_tokens_file = None
-            else:
-                logger.info("loading special tokens file {}".format(special_tokens_file))
-        # redirect to the cache, if necessary
-        try:
-            resolved_vocab_file = cached_path(vocab_file, cache_dir=cache_dir)
-        except EnvironmentError:
-            if pretrained_model_name_or_path in PRETRAINED_VOCAB_ARCHIVE_MAP:
-                logger.error(
-                    "Couldn't reach server at '{}' to download vocabulary.".format(
-                        vocab_file))
-            else:
-                logger.error(
-                    "Model name '{}' was not found in model name list ({}). "
-                    "We assumed '{}' was a path or url but couldn't find files {}"
-                    "at this path or url.".format(
-                        pretrained_model_name_or_path,
-                        ', '.join(PRETRAINED_VOCAB_ARCHIVE_MAP.keys()),
-                        pretrained_model_name_or_path,
-                        vocab_file))
-            return None
-        if resolved_vocab_file == vocab_file:
-            logger.info("loading vocabulary file {}".format(vocab_file))
-        else:
-            logger.info("loading vocabulary file {} from cache at {}".format(
-                vocab_file, resolved_vocab_file))
-        # Instantiate tokenizer.
-        if special_tokens_file and 'special_tokens' not in kwargs:
-            special_tokens = open(special_tokens_file, encoding='utf-8').read().split('\n')[:-1]
-        else:
-            special_tokens = kwargs.pop('special_tokens', [])
-        tokenizer = cls(resolved_vocab_file, special_tokens=special_tokens, *inputs, **kwargs)
-        return tokenizer
+    vocab_files_names = VOCAB_FILES_NAMES
+    pretrained_vocab_files_map = PRETRAINED_VOCAB_FILES_MAP
+    max_model_input_sizes = PRETRAINED_POSITIONAL_EMBEDDINGS_SIZES
 
-    def __init__(self, vocab_file, special_tokens=None, max_len=None,
+    def __init__(self, vocab_file, max_len=None,
                  do_lower_case=False, remove_space=True, keep_accents=False):
         try:
             import sentencepiece as spm
@@ -136,9 +92,6 @@ class XLNetTokenizer(object):
 
         self.sp_model = spm.SentencePieceProcessor()
         self.sp_model.Load(vocab_file)
-        self.special_tokens = {}
-        self.special_tokens_decoder = {}
-        self.set_special_tokens(special_tokens)
 
     @property
     def UNK_TOKEN(self):
@@ -181,7 +134,7 @@ class XLNetTokenizer(object):
         return self.special_symbols["<mask>"]
 
     def __len__(self):
-        return len(self.encoder) + len(self.special_tokens)
+        return len(self.sp_model)
 
     def __getstate__(self):
         state = self.__dict__.copy()
@@ -198,19 +151,6 @@ class XLNetTokenizer(object):
         self.sp_model = spm.SentencePieceProcessor()
         self.sp_model.Load(self.vocab_file)
 
-    def set_special_tokens(self, special_tokens):
-        """ Add a list of additional tokens to the encoder.
-            The additional tokens are indexed starting from the last index of the
-            current vocabulary in the order of the `special_tokens` list.
-        """
-        if not special_tokens:
-            self.special_tokens = {}
-            self.special_tokens_decoder = {}
-            return
-        self.special_tokens = dict((tok, len(self.sp_model) + i) for i, tok in enumerate(special_tokens))
-        self.special_tokens_decoder = {v:k for k, v in self.special_tokens.items()}
-        logger.info("Special tokens: %s", str(self.special_tokens))
-
     def preprocess_text(self, inputs):
         if self.remove_space:
             outputs = ' '.join(inputs.strip().split())
@@ -272,15 +212,9 @@ class XLNetTokenizer(object):
         """ Converts a sequence of tokens into ids using the vocab. """
         ids = []
         if isinstance(tokens, str) or (sys.version_info[0] == 2 and isinstance(tokens, unicode)):
-            if tokens in self.special_tokens:
-                return self.special_tokens[tokens]
-            else:
-                return self.sp_model.PieceToId(tokens)
+            return self.sp_model.PieceToId(tokens)
         for token in tokens:
-            if token in self.special_tokens:
-                ids.append(self.special_tokens[token])
-            else:
-                ids.append(self.sp_model.PieceToId(token))
+            ids.append(self.sp_model.PieceToId(token))
         if len(ids) > self.max_len:
             logger.warning(
                 "Token indices sequence length is longer than the specified maximum "
@@ -289,15 +223,11 @@ class XLNetTokenizer(object):
             )
         return ids
 
-    def convert_ids_to_tokens(self, ids, return_unicode=True, skip_special_tokens=False):
+    def convert_ids_to_tokens(self, ids, return_unicode=True):
         """Converts a sequence of ids in tokens."""
         tokens = []
         for i in ids:
-            if i in self.special_tokens_decoder:
-                if not skip_special_tokens:
-                    tokens.append(self.special_tokens_decoder[i])
-            else:
-                tokens.append(self.sp_model.IdToPiece(i))
+            tokens.append(self.sp_model.IdToPiece(i))
 
         if six.PY2 and return_unicode:
             ret_pieces = []
@@ -311,9 +241,9 @@ class XLNetTokenizer(object):
     def encode(self, text, sample=False):
         return self.convert_tokens_to_ids(self.tokenize(text, sample=sample))
 
-    def decode(self, ids, skip_special_tokens=False, clean_up_tokenization_spaces=True):
+    def decode(self, ids, clean_up_tokenization_spaces=True):
         """Converts a sequence of ids in a string."""
-        tokens = self.convert_ids_to_tokens(ids, skip_special_tokens=skip_special_tokens)
+        tokens = self.convert_ids_to_tokens(ids)
         out_string = ''.join(tokens)
         if clean_up_tokenization_spaces:
             out_string = out_string.strip().replace('<unk>', '')
@@ -328,18 +258,7 @@ class XLNetTokenizer(object):
             logger.error("Vocabulary path ({}) should be a directory".format(vocab_path))
             return
         out_vocab_file = os.path.join(vocab_path, VOCAB_NAME)
-        special_tokens_file = os.path.join(vocab_path, SPECIAL_TOKENS_NAME)
 
         copyfile(self.vocab_file, out_vocab_file)
 
-        index = len(self.sp_model)
-        with open(special_tokens_file, 'w', encoding='utf-8') as writer:
-            for token, token_index in sorted(self.special_tokens.items(), key=lambda kv: kv[1]):
-                if index != token_index:
-                    logger.warning("Saving special tokens vocabulary to {}: BPE indices are not consecutive."
-                                   " Please check that the tokenizer is not corrupted!".format(special_tokens_file))
-                    index = token_index
-                writer.write(token + u'\n')
-                index += 1
-
-        return out_vocab_file, special_tokens_file
+        return (out_vocab_file,)