[Chore] Enable passing `tokenizer=None` into MM processor (#29724)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/multimodal/test_processing.py

@@ -3,7 +3,6 @@
 
 import time
 from contextlib import nullcontext
-from typing import cast
 
 import numpy as np
 import pytest
@@ -24,7 +23,6 @@ from vllm.multimodal.processing import (
     replace_token_matches,
 )
 from vllm.multimodal.profiling import MultiModalProfiler
-from vllm.tokenizers import TokenizerLike
 
 from .utils import random_image
 
@@ -238,15 +236,12 @@ def test_find_token_matches(
     expected_by_key,
     update_type,
 ):
-    # Should not be used since there is nothing to convert to token IDs
-    mock_tokenizer = cast(TokenizerLike, object())
-
     prompt_updates = {
         key: update_type(key, target, []).resolve(0)
         for key, target in target_by_key.items()
     }
     result = {
-        key: list(update.iter_token_matches(prompt, mock_tokenizer))
+        key: list(update.iter_token_matches(prompt, tokenizer=None))
         for key, update in prompt_updates.items()
     }
 
@@ -385,15 +380,12 @@ def test_find_text_matches(
     expected_by_key,
     update_type,
 ):
-    # Should not be used since there is nothing to convert to text
-    mock_tokenizer = cast(TokenizerLike, object())
-
     prompt_updates = {
         key: update_type(key, target, []).resolve(0)
         for key, target in target_by_key.items()
     }
     result = {
-        key: list(update.iter_text_matches(prompt, mock_tokenizer))
+        key: list(update.iter_text_matches(prompt, tokenizer=None))
         for key, update in prompt_updates.items()
     }
 
@@ -545,9 +537,6 @@ def test_find_update_text(
     repl_by_key,
     expected_by_update_type_mm_count,
 ):
-    # Should not be used since there is nothing to convert to text
-    mock_tokenizer = cast(TokenizerLike, object())
-
     for (
         update_type,
         expected_by_mm_count,
@@ -564,7 +553,7 @@ def test_find_update_text(
             new_prompt, result = apply_text_matches(
                 prompt,
                 mm_prompt_updates,
-                mock_tokenizer,
+                tokenizer=None,
             )
 
             # Only displayed on error
@@ -750,9 +739,6 @@ def test_find_update_tokens(
     repl_by_key,
     expected_by_update_type_mm_count,
 ):
-    # Should not be used since there is nothing to convert to tokens
-    mock_tokenizer = cast(TokenizerLike, object())
-
     for (
         update_type,
         expected_by_mm_count,
@@ -769,7 +755,7 @@ def test_find_update_tokens(
             new_prompt, result = apply_token_matches(
                 prompt,
                 mm_prompt_updates,
-                mock_tokenizer,
+                tokenizer=None,
             )
 
             # Only displayed on error
@@ -900,15 +886,12 @@ def test_find_mm_placeholders(
     expected,
     update_type,
 ):
-    # Should not be used since there is nothing to convert to tokens
-    mock_tokenizer = cast(TokenizerLike, object())
-
     mm_prompt_updates = {
         key: [[update_type(key, [], repl).resolve(i)] for i in range(3)]
         for key, repl in repl_by_key.items()
     }
 
-    result = find_mm_placeholders(prompt, mm_prompt_updates, mock_tokenizer)
+    result = find_mm_placeholders(prompt, mm_prompt_updates, tokenizer=None)
 
     # Only displayed on error
     print("result:", result)
@@ -1029,12 +1012,9 @@ def test_hf_processor_init_kwargs(
     inference_kwargs,
     expected_kwargs,
 ):
-    # Should not be used since there is nothing to convert to tokens
-    mock_tokenizer = cast(TokenizerLike, object())
-
     ctx = InputProcessingContext(
         model_config=ModelConfig(model_id, mm_processor_kwargs=config_kwargs),
-        tokenizer=mock_tokenizer,
+        tokenizer=None,
     )
 
     processor = ctx.get_hf_processor(
@@ -1065,12 +1045,9 @@ def test_hf_processor_call_kwargs(
     inference_kwargs,
     expected_kwargs,
 ):
-    # Should not be used since there is nothing to convert to tokens
-    mock_tokenizer = cast(TokenizerLike, object())
-
     ctx = InputProcessingContext(
         model_config=ModelConfig(model_id, mm_processor_kwargs=config_kwargs),
-        tokenizer=mock_tokenizer,
+        tokenizer=None,
     )
 
     processor = ctx.get_hf_processor(DummyProcessor)  # type: ignore[arg-type]
@@ -1089,8 +1066,6 @@ def test_apply_matches_no_match_exits_quickly():
 
     With the fix, it should exit immediately when no match is found.
     """
-    mock_tokenizer = cast(TokenizerLike, object())
-
     # Create a long prompt with no placeholder
     long_prompt = "x" * 10000
 
@@ -1103,7 +1078,7 @@ def test_apply_matches_no_match_exits_quickly():
     result, _ = _apply_matches(
         long_prompt,
         mm_prompt_updates,
-        mock_tokenizer,
+        tokenizer=None,
     )
     elapsed = time.perf_counter() - start
 

vllm/entrypoints/openai/serving_engine.py

@@ -337,7 +337,7 @@ class OpenAIServing:
         tokenizer = input_processor.tokenizer
         if tokenizer is None:
             raise ValueError(
-                "You cannot use beam search when `skip_tokenizer_init` is True"
+                "You cannot use beam search when `skip_tokenizer_init=True`"
             )
 
         eos_token_id: int = tokenizer.eos_token_id  # type: ignore

vllm/inputs/preprocess.py

@@ -62,7 +62,7 @@ class InputPreprocessor:
     def get_tokenizer(self) -> TokenizerLike:
         if self.tokenizer is None:
             raise ValueError(
-                "You cannot pass text prompts when `skip_tokenizer_init` is True"
+                "You cannot pass text prompts when `skip_tokenizer_init=True`"
             )
 
         return self.tokenizer
@@ -228,22 +228,11 @@ class InputPreprocessor:
 
         return tokenizer.encode(prompt, **tokenization_kwargs)
 
-    def _get_mm_tokenizer(self) -> TokenizerLike:
-        # PrithviGeoSpatialMAE needs to be initialized without a tokenizer
-        # while using also multi-modal input
-        if not self.tokenizer:
-            return cast(TokenizerLike, object())  # Dummy
-
-        tokenizer = self.get_tokenizer()
-        return tokenizer
-
     def _get_mm_processor(self) -> BaseMultiModalProcessor:
         if not hasattr(self, "_mm_processor"):
-            tokenizer = self._get_mm_tokenizer()
-
             self._mm_processor = self.mm_registry.create_processor(
                 self.model_config,
-                tokenizer=tokenizer,
+                tokenizer=self.tokenizer,
                 cache=self.mm_processor_cache,
             )
 

vllm/model_executor/models/glm4_1v.py

@@ -866,12 +866,6 @@ class Glm4vVisionTransformer(nn.Module):
 
 
 class Glm4vProcessingInfo(BaseProcessingInfo):
-    def get_hf_config(self):
-        return self.ctx.get_hf_config()
-
-    def get_tokenizer(self):
-        return self.ctx.tokenizer
-
     def get_supported_mm_limits(self) -> Mapping[str, int | None]:
         return {"image": None, "video": 1}
 

vllm/model_executor/models/qwen3_vl.py

@@ -615,9 +615,6 @@ class Qwen3VLProcessingInfo(Qwen2VLProcessingInfo):
             **kwargs,
         )
 
-    def get_tokenizer(self):
-        return self.ctx.tokenizer
-
     def get_image_processor(self, **kwargs: object) -> Qwen2VLImageProcessorFast:
         return self.get_hf_processor(**kwargs).image_processor
 

vllm/model_executor/models/qwen_vl.py

@@ -555,7 +555,7 @@ class QwenVLProcessor:
 
 class QwenVLProcessingInfo(BaseProcessingInfo):
     def get_tokenizer(self) -> PreTrainedTokenizer:
-        tokenizer = self.ctx.tokenizer
+        tokenizer = self.ctx.get_tokenizer()
         assert isinstance(tokenizer, PreTrainedTokenizer)
 
         return _get_tokenizer_without_image_pad(tokenizer)

vllm/multimodal/processing.py

@@ -97,15 +97,37 @@ def _cached_decode(
     )
 
 
-def _seq2text(tokenizer: TokenizerLike, seq: PromptSeq) -> str:
+def _seq2text(
+    tokenizer: TokenizerLike | None,
+    seq: PromptSeq,
+    *,
+    use_cache: bool = True,
+) -> str:
     if isinstance(seq, str):
         return seq
 
+    if tokenizer is None:
+        raise ValueError("You cannot decode tokens when `skip_tokenizer_init=True`")
+
+    if not use_cache:
+        return decode_tokens(tokenizer, seq)
+
     return _cached_decode(tokenizer, tuple(seq))
 
 
-def _seq2tokens(tokenizer: TokenizerLike, seq: PromptSeq) -> list[int]:
+def _seq2tokens(
+    tokenizer: TokenizerLike | None,
+    seq: PromptSeq,
+    *,
+    use_cache: bool = True,
+) -> list[int]:
     if isinstance(seq, str):
+        if tokenizer is None:
+            raise ValueError("You cannot encode text when `skip_tokenizer_init=True`")
+
+        if not use_cache:
+            return encode_tokens(tokenizer, seq, add_special_tokens=False)
+
         return _cached_encode(tokenizer, seq, add_special_tokens=False)
 
     return seq
@@ -114,7 +136,7 @@ def _seq2tokens(tokenizer: TokenizerLike, seq: PromptSeq) -> list[int]:
 class _GetMatchIndex(Protocol):
     def __call__(
         self,
-        tokenizer: TokenizerLike,
+        tokenizer: TokenizerLike | None,
         prompt: PromptSeq,
         start_idx: int = 0,
     ) -> int | None: ...
@@ -144,7 +166,7 @@ class PromptIndexTargets:
         """
 
         def get_match_index(
-            tokenizer: TokenizerLike,
+            tokenizer: TokenizerLike | None,
             prompt: PromptSeq,
             start_idx: int = 0,
         ) -> int | None:
@@ -154,13 +176,11 @@ class PromptIndexTargets:
             prefix = seq
 
             if isinstance(prompt, str):
-                if not isinstance(prefix, str):
                 # Make both `str`
-                    prefix = decode_tokens(tokenizer, prefix)
+                prefix = _seq2text(tokenizer, prefix, use_cache=False)
             else:
-                if isinstance(prefix, str):
                 # Make both `list[int]`
-                    prefix = encode_tokens(tokenizer, prefix, add_special_tokens=False)
+                prefix = _seq2tokens(tokenizer, prefix, use_cache=False)
 
             match_idx = len(prefix)
             return match_idx if prompt[:match_idx] == prefix else None
@@ -200,7 +220,7 @@ class PromptUpdateDetails(Generic[_S]):
     full: _S
     """The full content."""
 
-    is_embed: Callable[[TokenizerLike, PromptSeq], torch.Tensor] | None = None
+    is_embed: Callable[[TokenizerLike | None, PromptSeq], torch.Tensor] | None = None
     """
     Given [`full`][vllm.multimodal.processing.PromptUpdateDetails.full],
     return a boolean mask of shape `(len(full),)` indicating which positions
@@ -221,8 +241,8 @@ class PromptUpdateDetails(Generic[_S]):
         seq: _S,
         embed_text: str,
     ) -> "PromptUpdateDetails[_S]":
-        def is_embed(tokenizer: TokenizerLike, full: PromptSeq) -> torch.Tensor:
-            embed_token_ids = encode_tokens(tokenizer, embed_text)
+        def is_embed(tokenizer: TokenizerLike | None, full: PromptSeq) -> torch.Tensor:
+            embed_token_ids = _seq2tokens(tokenizer, embed_text, use_cache=False)
             token_ids = _seq2tokens(tokenizer, full)
 
             return torch.isin(
@@ -237,7 +257,7 @@ class PromptUpdateDetails(Generic[_S]):
         seq: _S,
         embed_token_id: int,
     ) -> "PromptUpdateDetails[_S]":
-        def is_embed(tokenizer: TokenizerLike, full: PromptSeq) -> torch.Tensor:
+        def is_embed(tokenizer: TokenizerLike | None, full: PromptSeq) -> torch.Tensor:
             token_ids = _seq2tokens(tokenizer, full)
 
             return torch.tensor(token_ids) == embed_token_id
@@ -523,7 +543,7 @@ class ResolvedPromptUpdate:
     def iter_token_matches(
         self,
         prompt: list[int],
-        tokenizer: TokenizerLike,
+        tokenizer: TokenizerLike | None,
         *,
         start_idx: int = 0,
     ) -> Generator[PromptTargetMatch]:
@@ -545,7 +565,7 @@ class ResolvedPromptUpdate:
     def iter_text_matches(
         self,
         prompt: str,
-        tokenizer: TokenizerLike,
+        tokenizer: TokenizerLike | None,
         *,
         start_idx: int = 0,
     ) -> Generator[PromptTargetMatch]:
@@ -567,7 +587,7 @@ class ResolvedPromptUpdate:
     def iter_matches(
         self,
         prompt: list[int] | str,
-        tokenizer: TokenizerLike,
+        tokenizer: TokenizerLike | None,
         *,
         start_idx: int = 0,
     ) -> Generator[PromptTargetMatch]:
@@ -676,7 +696,7 @@ _MatchToApply = tuple[tuple[str, int], tuple[PromptTargetMatch, int]]
 def _find_matches(
     prompt: _S,
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
     *,
     prev_end_idx: int = 0,
     current_result: "MultiModalPromptUpdatesApplyResult",
@@ -741,7 +761,7 @@ def _all_items_found(
 def _apply_matches(
     prompt: _S,
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
 ) -> tuple[list[_S], "MultiModalPromptUpdatesApplyResult"]:
     mm_item_counts = {m: len(items) for m, items in mm_prompt_updates.items()}
 
@@ -807,7 +827,7 @@ def _apply_matches(
 def apply_token_matches(
     prompt: list[int],
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
 ) -> tuple[list[int], "MultiModalPromptUpdatesApplyResult"]:
     """
     Apply the updates in `mm_prompt_updates` to `prompt`.
@@ -824,7 +844,7 @@ def apply_token_matches(
 def apply_text_matches(
     prompt: str,
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
 ) -> tuple[str, "MultiModalPromptUpdatesApplyResult"]:
     """
     Apply the updates in `mm_prompt_updates` to `prompt`.
@@ -841,7 +861,7 @@ def apply_text_matches(
 def _iter_placeholders(
     prompt: list[int],
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
 ) -> Iterable[PlaceholderFeaturesInfo]:
     """
     Yield each set of placeholder tokens found in `prompt`.
@@ -910,7 +930,7 @@ def _iter_placeholders(
 def find_mm_placeholders(
     prompt: list[int],
     mm_prompt_updates: "MultiModalPromptUpdates",
-    tokenizer: TokenizerLike,
+    tokenizer: TokenizerLike | None,
 ) -> Mapping[str, list[PlaceholderFeaturesInfo]]:
     it = _iter_placeholders(prompt, mm_prompt_updates, tokenizer)
     return dict(full_groupby_modality(it))
@@ -931,9 +951,17 @@ class InputProcessingContext:
     model_config: ModelConfig
     """The configuration of the model."""
 
-    tokenizer: TokenizerLike
+    tokenizer: TokenizerLike | None
     """The tokenizer used to tokenize the inputs."""
 
+    def get_tokenizer(self) -> TokenizerLike:
+        if self.tokenizer is None:
+            raise ValueError(
+                "You cannot pass text prompts when `skip_tokenizer_init=True`"
+            )
+
+        return self.tokenizer
+
     @overload
     def get_hf_config(self, /) -> PretrainedConfig: ...
 
@@ -1148,7 +1176,7 @@ class BaseProcessingInfo:
         return self.ctx.model_config.model
 
     def get_tokenizer(self) -> TokenizerLike:
-        return self.ctx.tokenizer
+        return self.ctx.get_tokenizer()
 
     def get_hf_config(self) -> PretrainedConfig:
         return self.ctx.get_hf_config()
@@ -1960,15 +1988,11 @@ class BaseMultiModalProcessor(ABC, Generic[_I]):
             for update_idxs in match_result.values()
         ):
             new_text, match_result = self._apply_text_matches(
-                decode_tokens(tokenizer, token_ids),
+                _seq2text(tokenizer, token_ids, use_cache=False),
                 mm_prompt_updates,
             )
 
-            new_token_ids = encode_tokens(
-                tokenizer,
-                new_text,
-                add_special_tokens=False,
-            )
+            new_token_ids = _seq2tokens(tokenizer, new_text, use_cache=False)
 
         matched_updates = defaultdict[str, list[Sequence[ResolvedPromptUpdate]]](list)
         for modality, update_idxs in match_result.items():

vllm/multimodal/registry.py

@@ -234,9 +234,7 @@ class MultiModalRegistry:
         model_config: "ModelConfig",
         tokenizer: TokenizerLike | None = None,
     ) -> InputProcessingContext:
-        if model_config.skip_tokenizer_init:
-            tokenizer = cast(TokenizerLike, object())
-        elif tokenizer is None:
+        if tokenizer is None and not model_config.skip_tokenizer_init:
             tokenizer = cached_tokenizer_from_config(model_config)
 
         return InputProcessingContext(model_config, tokenizer)