fast tok update (#13036)

* v5 tok update

* ruff

* keep pre v5 slow code path

* Apply style fixes

---------

Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: 3 people

src/diffusers/loaders/textual_inversion.py

@@ -11,11 +11,13 @@
 # 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.
+import json
 from typing import Dict, List, Optional, Union
 
 import safetensors
 import torch
 from huggingface_hub.utils import validate_hf_hub_args
+from tokenizers import Tokenizer as TokenizerFast
 from torch import nn
 
 from ..models.modeling_utils import load_state_dict
@@ -547,23 +549,39 @@ def unload_textual_inversion(
                 else:
                     last_special_token_id = added_token_id
 
-        # Delete from tokenizer
-        for token_id, token_to_remove in zip(token_ids, tokens):
-            del tokenizer._added_tokens_decoder[token_id]
-            del tokenizer._added_tokens_encoder[token_to_remove]
-
-        # Make all token ids sequential in tokenizer
-        key_id = 1
-        for token_id in tokenizer.added_tokens_decoder:
-            if token_id > last_special_token_id and token_id > last_special_token_id + key_id:
-                token = tokenizer._added_tokens_decoder[token_id]
-                tokenizer._added_tokens_decoder[last_special_token_id + key_id] = token
+        # Fast tokenizers (v5+)
+        if hasattr(tokenizer, "_tokenizer"):
+            # Fast tokenizers: serialize, filter tokens, reload
+            tokenizer_json = json.loads(tokenizer._tokenizer.to_str())
+            new_id = last_special_token_id + 1
+            filtered = []
+            for tok in tokenizer_json.get("added_tokens", []):
+                if tok.get("content") in set(tokens):
+                    continue
+                if not tok.get("special", False):
+                    tok["id"] = new_id
+                    new_id += 1
+                filtered.append(tok)
+            tokenizer_json["added_tokens"] = filtered
+            tokenizer._tokenizer = TokenizerFast.from_str(json.dumps(tokenizer_json))
+        else:
+            # Slow tokenizers
+            for token_id, token_to_remove in zip(token_ids, tokens):
                 del tokenizer._added_tokens_decoder[token_id]
-                tokenizer._added_tokens_encoder[token.content] = last_special_token_id + key_id
-                key_id += 1
-        tokenizer._update_trie()
-        # set correct total vocab size after removing tokens
-        tokenizer._update_total_vocab_size()
+                del tokenizer._added_tokens_encoder[token_to_remove]
+
+            key_id = 1
+            for token_id in list(tokenizer.added_tokens_decoder.keys()):
+                if token_id > last_special_token_id and token_id > last_special_token_id + key_id:
+                    token = tokenizer._added_tokens_decoder[token_id]
+                    tokenizer._added_tokens_decoder[last_special_token_id + key_id] = token
+                    del tokenizer._added_tokens_decoder[token_id]
+                    tokenizer._added_tokens_encoder[token.content] = last_special_token_id + key_id
+                    key_id += 1
+            if hasattr(tokenizer, "_update_trie"):
+                tokenizer._update_trie()
+            if hasattr(tokenizer, "_update_total_vocab_size"):
+                tokenizer._update_total_vocab_size()
 
         # Delete from text encoder
         text_embedding_dim = text_encoder.get_input_embeddings().embedding_dim