saving and reloading tokenizer configurations

pytorch_transformers/tokenization_utils.py

@@ -20,6 +20,7 @@ import logging
 import os
 import json
 import six
+import copy
 from io import open
 
 from .file_utils import cached_path
@@ -28,6 +29,7 @@ logger = logging.getLogger(__name__)
 
 SPECIAL_TOKENS_MAP_FILE = 'special_tokens_map.json'
 ADDED_TOKENS_FILE = 'added_tokens.json'
+TOKENIZER_CONFIG_FILE = 'tokenizer_config.json'
 
 class PreTrainedTokenizer(object):
     """ Base class for all tokenizers.
@@ -168,9 +170,15 @@ class PreTrainedTokenizer(object):
         self._additional_special_tokens = []
 
         self.max_len = max_len if max_len is not None else int(1e12)
+
+        # Added tokens
         self.added_tokens_encoder = {}
         self.added_tokens_decoder = {}
 
+        # inputs and kwargs for saving and re-loading (see ``from_pretrained`` and ``save_pretrained``)
+        self.init_inputs = ()
+        self.init_kwargs = {}
+
         for key, value in kwargs.items():
             if key in self.SPECIAL_TOKENS_ATTRIBUTES:
                 if key == 'additional_special_tokens':
@@ -230,7 +238,7 @@ class PreTrainedTokenizer(object):
 
 
     @classmethod
-    def _from_pretrained(cls, pretrained_model_name_or_path, *inputs, **kwargs):
+    def _from_pretrained(cls, pretrained_model_name_or_path, *init_inputs, **kwargs):
         cache_dir = kwargs.pop('cache_dir', None)
         force_download = kwargs.pop('force_download', False)
         proxies = kwargs.pop('proxies', None)
@@ -266,15 +274,17 @@ class PreTrainedTokenizer(object):
                 vocab_files[file_id] = full_file_name
 
             # Look for the additional tokens files
-            all_vocab_files_names = {'added_tokens_file': ADDED_TOKENS_FILE,
+            additional_files_names = {'added_tokens_file': ADDED_TOKENS_FILE,
-                                     'special_tokens_map_file': SPECIAL_TOKENS_MAP_FILE}
+                                      'special_tokens_map_file': SPECIAL_TOKENS_MAP_FILE,
+                                      'tokenizer_config_file': TOKENIZER_CONFIG_FILE,
+                                      }
 
             # If a path to a file was provided, get the parent directory
             saved_directory = pretrained_model_name_or_path
             if os.path.exists(saved_directory) and not os.path.isdir(saved_directory):
                 saved_directory = os.path.dirname(saved_directory)
 
-            for file_id, file_name in all_vocab_files_names.items():
+            for file_id, file_name in additional_files_names.items():
                 full_file_name = os.path.join(saved_directory, file_name)
                 if not os.path.exists(full_file_name):
                     logger.info("Didn't find file {}. We won't load it.".format(full_file_name))
@@ -317,8 +327,18 @@ class PreTrainedTokenizer(object):
                 logger.info("loading file {} from cache at {}".format(
                     file_path, resolved_vocab_files[file_id]))
 
-        # Prepare initialization kwargs
+        # Prepare tokenizer initialization kwargs
+        # Did we saved some inputs and kwargs to reload ?
+        tokenizer_config_file = resolved_vocab_files.pop('tokenizer_config_file', None)
+        if tokenizer_config_file is not None:
+            init_kwargs = json.load(open(tokenizer_config_file, encoding="utf-8"))
+            saved_init_inputs = init_kwargs.pop('init_inputs', [])
+            if not init_inputs:
+                init_inputs = saved_init_inputs
+        else:
             init_kwargs = init_configuration
+
+        # Update with newly provided kwargs
         init_kwargs.update(kwargs)
 
         # Set max length if needed
@@ -342,7 +362,11 @@ class PreTrainedTokenizer(object):
                     init_kwargs[key] = value
 
         # Instantiate tokenizer.
-        tokenizer = cls(*inputs, **init_kwargs)
+        tokenizer = cls(*init_inputs, **init_kwargs)
+
+        # Save inputs and kwargs for saving and re-loading with ``save_pretrained``
+        tokenizer.init_inputs = init_inputs
+        tokenizer.init_kwargs = init_kwargs
 
         # Add supplementary tokens.
         if added_tokens_file is not None:
@@ -355,8 +379,13 @@ class PreTrainedTokenizer(object):
 
 
     def save_pretrained(self, save_directory):
-        """ Save the tokenizer vocabulary files (with added tokens) and the
+        """ Save the tokenizer vocabulary files together with:
-            special-tokens-to-class-attributes-mapping to a directory.
+                - added tokens,
+                - special-tokens-to-class-attributes-mapping,
+                - tokenizer instantiation positional and keywords inputs (e.g. do_lower_case for Bert).
+
+            This won't save modifications other than (added tokens and special token mapping) you may have
+            applied to the tokenizer after the instantion (e.g. modifying tokenizer.do_lower_case after creation).
 
             This method make sure the full tokenizer can then be re-loaded using the :func:`~pytorch_transformers.PreTrainedTokenizer.from_pretrained` class method.
         """
@@ -366,6 +395,13 @@ class PreTrainedTokenizer(object):
 
         special_tokens_map_file = os.path.join(save_directory, SPECIAL_TOKENS_MAP_FILE)
         added_tokens_file = os.path.join(save_directory, ADDED_TOKENS_FILE)
+        tokenizer_config_file = os.path.join(save_directory, TOKENIZER_CONFIG_FILE)
+
+        tokenizer_config = copy.deepcopy(self.init_kwargs)
+        tokenizer_config['init_inputs'] = copy.deepcopy(self.init_inputs)
+
+        with open(tokenizer_config_file, 'w', encoding='utf-8') as f:
+            f.write(json.dumps(tokenizer_config, ensure_ascii=False))
 
         with open(special_tokens_map_file, 'w', encoding='utf-8') as f:
             f.write(json.dumps(self.special_tokens_map, ensure_ascii=False))