[Core] Support serving encoder/decoder models (#7258)

.github/workflows/mypy.yaml

@@ -25,7 +25,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install mypy==1.9.0
+        pip install mypy==1.11.1
         pip install types-setuptools
         pip install types-PyYAML
         pip install types-requests

examples/offline_inference_encoder_decoder.py

@@ -4,8 +4,8 @@ encoder/decoder models, specifically BART
 '''
 
 from vllm import LLM, SamplingParams
-from vllm.inputs import ExplicitEncoderDecoderPrompt, TextPrompt, TokensPrompt
-from vllm.utils import zip_enc_dec_prompt_lists
+from vllm.inputs import (ExplicitEncoderDecoderPrompt, TextPrompt,
+                         TokensPrompt, zip_enc_dec_prompts)
 
 dtype = "float"
 
@@ -61,9 +61,9 @@ enc_dec_prompt3 = ExplicitEncoderDecoderPrompt(
 )
 
 # - Finally, here's a useful helper function for zipping encoder and
-#   decoder prompt lists together into a list of ExplicitEncoderDecoderPrompt
+#   decoder prompts together into a list of ExplicitEncoderDecoderPrompt
 #   instances
-zipped_prompt_list = zip_enc_dec_prompt_lists(
+zipped_prompt_list = zip_enc_dec_prompts(
     ['An encoder prompt', 'Another encoder prompt'],
     ['A decoder prompt', 'Another decoder prompt'])
 

requirements-common.txt

@@ -19,7 +19,7 @@ prometheus-fastapi-instrumentator >= 7.0.0
 tiktoken >= 0.6.0  # Required for DBRX tokenizer
 lm-format-enforcer == 0.10.3
 outlines >= 0.0.43, < 0.1 # Requires torch >= 2.1.0
-typing_extensions
+typing_extensions >= 4.10
 filelock >= 3.10.4 # filelock starts to support `mode` argument from 3.10.4
 pyzmq
 gguf == 0.9.1

requirements-lint.txt

@@ -8,7 +8,7 @@ isort==5.13.2
 clang-format==18.1.5
 
 # type checking
-mypy==1.9.0
+mypy==1.11.1
 types-PyYAML
 types-requests
 types-setuptools

tests/conftest.py

@@ -3,6 +3,7 @@ import gc
 import os
 import sys
 from collections import UserList
+from enum import Enum
 from typing import Any, Dict, List, Optional, Tuple, TypedDict, TypeVar, Union
 
 import pytest
@@ -14,20 +15,19 @@ from transformers import (AutoModelForCausalLM, AutoModelForSeq2SeqLM,
                           AutoModelForVision2Seq, AutoTokenizer, BatchEncoding,
                           BatchFeature)
 
-from tests.models.utils import DecoderPromptType
 from vllm import LLM, SamplingParams
 from vllm.assets.image import ImageAsset
 from vllm.config import TokenizerPoolConfig
 from vllm.connections import global_http_connection
 from vllm.distributed import (destroy_distributed_environment,
                               destroy_model_parallel)
-from vllm.inputs import TextPrompt
+from vllm.inputs import (ExplicitEncoderDecoderPrompt, TextPrompt,
+                         to_enc_dec_tuple_list, zip_enc_dec_prompts)
 from vllm.logger import init_logger
 from vllm.outputs import RequestOutput
 from vllm.sequence import SampleLogprobs
 from vllm.utils import (STR_DTYPE_TO_TORCH_DTYPE, cuda_device_count_stateless,
-                        is_cpu, to_enc_dec_tuple_list,
-                        zip_enc_dec_prompt_lists)
+                        is_cpu)
 
 logger = init_logger(__name__)
 
@@ -124,10 +124,16 @@ def example_prompts() -> List[str]:
     return prompts
 
 
+class DecoderPromptType(Enum):
+    """For encoder/decoder models only."""
+    CUSTOM = 1
+    NONE = 2
+    EMPTY_STR = 3
+
+
 @pytest.fixture
-def example_encoder_decoder_prompts() \
-    -> Dict[DecoderPromptType,
-            Tuple[List[str], List[Optional[str]]]]:
+def example_encoder_decoder_prompts(
+) -> Dict[DecoderPromptType, List[ExplicitEncoderDecoderPrompt]]:
     '''
     Returns an encoder prompt list and a decoder prompt list, wherein each pair
     of same-index entries in both lists corresponds to an (encoder prompt,
@@ -150,11 +156,11 @@ def example_encoder_decoder_prompts() \
     # NONE decoder prompt type
     return {
         DecoderPromptType.NONE:
-        zip_enc_dec_prompt_lists(encoder_prompts, none_decoder_prompts),
+        zip_enc_dec_prompts(encoder_prompts, none_decoder_prompts),
         DecoderPromptType.EMPTY_STR:
-        zip_enc_dec_prompt_lists(encoder_prompts, empty_str_decoder_prompts),
+        zip_enc_dec_prompts(encoder_prompts, empty_str_decoder_prompts),
         DecoderPromptType.CUSTOM:
-        zip_enc_dec_prompt_lists(encoder_prompts, custom_decoder_prompts),
+        zip_enc_dec_prompts(encoder_prompts, custom_decoder_prompts),
     }
 
 
@@ -444,7 +450,7 @@ class HfRunner:
 
     def generate_encoder_decoder_greedy_logprobs_limit(
         self,
-        encoder_decoder_prompts: Tuple[List[str], List[str]],
+        encoder_decoder_prompts: List[ExplicitEncoderDecoderPrompt[str, str]],
         max_tokens: int,
         num_logprobs: int,
         **kwargs: Any,
@@ -608,7 +614,7 @@ class VllmRunner:
 
     def generate_encoder_decoder_w_logprobs(
         self,
-        encoder_decoder_prompts: Tuple[List[str], List[str]],
+        encoder_decoder_prompts: List[ExplicitEncoderDecoderPrompt[str, str]],
         sampling_params: SamplingParams,
     ) -> List[Tuple[List[int], str, Optional[SampleLogprobs]]]:
         '''
@@ -653,7 +659,7 @@ class VllmRunner:
 
     def generate_encoder_decoder_greedy_logprobs(
         self,
-        encoder_decoder_prompts: Tuple[List[str], List[str]],
+        encoder_decoder_prompts: List[ExplicitEncoderDecoderPrompt[str, str]],
         max_tokens: int,
         num_logprobs: int,
     ) -> List[Tuple[List[int], str, Optional[SampleLogprobs]]]:

tests/distributed/test_basic_distributed_correctness_enc_dec.py

@@ -11,9 +11,9 @@ pytest distributed/test_basic_distributed_correctness_enc_dec.py
 
 import pytest
 
-from tests.models.utils import DecoderPromptType
 from vllm.utils import cuda_device_count_stateless
 
+from ..conftest import DecoderPromptType
 from ..models.utils import check_logprobs_close
 from ..utils import fork_new_process_for_each_test
 

tests/entrypoints/openai/test_encoder_decoder.py

+import openai
+import pytest
+
+from ...utils import RemoteOpenAIServer
+
+MODEL_NAME = "facebook/bart-base"
+
+
+@pytest.fixture(scope="module")
+def server():
+    args = [
+        "--dtype",
+        "bfloat16",
+        "--enforce-eager",
+    ]
+
+    with RemoteOpenAIServer(MODEL_NAME, args) as remote_server:
+        yield remote_server
+
+
+@pytest.fixture(scope="module")
+def client(server):
+    return server.get_async_client()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("model_name", [MODEL_NAME])
+async def test_single_completion(client: openai.AsyncOpenAI, model_name: str):
+    completion = await client.completions.create(model=model_name,
+                                                 prompt="Hello, my name is",
+                                                 max_tokens=5,
+                                                 temperature=0.0)
+
+    assert completion.id is not None
+    assert completion.choices is not None and len(completion.choices) == 1
+
+    choice = completion.choices[0]
+    assert len(choice.text) >= 5
+    assert choice.finish_reason == "length"
+    assert completion.usage == openai.types.CompletionUsage(
+        completion_tokens=5, prompt_tokens=2, total_tokens=7)
+
+    # test using token IDs
+    completion = await client.completions.create(
+        model=model_name,
+        prompt=[0, 0, 0, 0, 0],
+        max_tokens=5,
+        temperature=0.0,
+    )
+    assert len(completion.choices[0].text) >= 1

tests/models/test_bart.py

@@ -2,6 +2,8 @@
 
 Run `pytest tests/models/test_bart.py`.
 """
+from typing import List, Optional, Tuple
+
 from vllm.utils import is_cpu
 
 if not is_cpu():
@@ -11,22 +13,31 @@ if not is_cpu():
 
     import pytest
 
-    from tests.models.utils import DecoderPromptType
+    from vllm.sequence import SampleLogprobs
 
+    from ..conftest import DecoderPromptType
     from .utils import check_logprobs_close
 
     MODELS = ["facebook/bart-base", "facebook/bart-large-cnn"]
 
-    DECODER_PROMPT_TYPES = ([
-        DecoderPromptType.CUSTOM, DecoderPromptType.EMPTY_STR,
-        DecoderPromptType.NONE
-    ])
+    def vllm_to_hf_output(
+        vllm_output: Tuple[List[int], str, Optional[SampleLogprobs]],
+        decoder_prompt_type: DecoderPromptType,
+    ):
+        """Sanitize vllm output to be comparable with hf output."""
+        output_ids, output_str, out_logprobs = vllm_output
+
+        hf_output_str = output_str + "</s>"
+        if decoder_prompt_type == DecoderPromptType.NONE:
+            hf_output_str = "<s>" + hf_output_str
+
+        return output_ids, hf_output_str, out_logprobs
 
     @pytest.mark.parametrize("model", MODELS)
     @pytest.mark.parametrize("dtype", ["float", "bfloat16"])
     @pytest.mark.parametrize("max_tokens", [64])
     @pytest.mark.parametrize("num_logprobs", [5])
-    @pytest.mark.parametrize("decoder_prompt_type", DECODER_PROMPT_TYPES)
+    @pytest.mark.parametrize("decoder_prompt_type", list(DecoderPromptType))
     def test_models(
         hf_runner,
         vllm_runner,
@@ -146,8 +157,13 @@ if not is_cpu():
         hf_skip_tokens = (1 if decoder_prompt_type == DecoderPromptType.NONE
                           else 0)
 
-        check_logprobs_close(outputs_0_lst=hf_outputs,
-                             outputs_1_lst=vllm_outputs,
-                             name_0="hf",
-                             name_1="vllm",
-                             num_outputs_0_skip_tokens=hf_skip_tokens)
+        check_logprobs_close(
+            outputs_0_lst=hf_outputs,
+            outputs_1_lst=[
+                vllm_to_hf_output(vllm_output, decoder_prompt_type)
+                for vllm_output in vllm_outputs
+            ],
+            name_0="hf",
+            name_1="vllm",
+            num_outputs_0_skip_tokens=hf_skip_tokens,
+        )

tests/models/utils.py

 import warnings
-from enum import Enum
 from typing import Dict, List, Optional, Sequence, Tuple, Union
 
 from vllm.sequence import SampleLogprobs
@@ -136,13 +135,3 @@ def check_logprobs_close(
                     warnings.simplefilter("always")
 
                     warnings.warn(fail_msg, stacklevel=2)
-
-
-class DecoderPromptType(Enum):
-    '''
-    For encoder/decoder models only -
-    
-    '''
-    CUSTOM = 1
-    NONE = 2
-    EMPTY_STR = 3

tests/test_inputs.py

@@ -2,7 +2,7 @@ from typing import List
 
 import pytest
 
-from vllm.inputs import parse_and_batch_prompt
+from vllm.inputs.parse import parse_and_batch_prompt
 
 STRING_INPUTS = [
     '',

vllm/config.py

@@ -464,6 +464,16 @@ class ModelConfig:
             if t != "attention"
         ])
 
+    @property
+    def is_encoder_decoder_model(self) -> bool:
+        """Extract the HF encoder/decoder model flag."""
+        return getattr(self.hf_config, "is_encoder_decoder", False)
+
+    @property
+    def is_embedding_model(self) -> bool:
+        """Extract the embedding model flag."""
+        return self.embedding_mode
+
 
 class CacheConfig:
     """Configuration for the KV cache.

vllm/engine/async_llm_engine.py

@@ -5,6 +5,7 @@ from typing import (AsyncGenerator, Callable, Dict, Iterable, List, Mapping,
                     Optional, Set, Tuple, Type, Union)
 
 from transformers import PreTrainedTokenizer
+from typing_extensions import assert_never
 
 import vllm.envs as envs
 from vllm.config import (DecodingConfig, EngineConfig, LoRAConfig, ModelConfig,
@@ -12,11 +13,14 @@ from vllm.config import (DecodingConfig, EngineConfig, LoRAConfig, ModelConfig,
 from vllm.core.scheduler import SchedulerOutputs
 from vllm.engine.arg_utils import AsyncEngineArgs
 from vllm.engine.async_timeout import asyncio_timeout
-from vllm.engine.llm_engine import LLMEngine
+from vllm.engine.llm_engine import (DecoderPromptComponents, LLMEngine,
+                                    PromptComponents)
 from vllm.engine.metrics import StatLoggerBase
 from vllm.executor.executor_base import ExecutorAsyncBase
 from vllm.executor.ray_utils import initialize_ray_cluster, ray
-from vllm.inputs import LLMInputs, PromptInputs
+from vllm.inputs import (EncoderDecoderLLMInputs, LLMInputs, PromptInputs,
+                         SingletonPromptInputs)
+from vllm.inputs.parse import is_explicit_encoder_decoder_prompt
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.outputs import EmbeddingRequestOutput, RequestOutput
@@ -293,38 +297,138 @@ class _AsyncLLMEngine(LLMEngine):
         """Stop the remote worker execution loop."""
         await self.model_executor.stop_remote_worker_execution_loop_async()
 
-    async def process_model_inputs_async(
+    async def _tokenize_prompt_async(
+        self,
+        prompt: str,
+        request_id: str,
+        lora_request: Optional[LoRARequest],
+    ) -> List[int]:
+        """Async version of :meth:`_tokenize_prompt`."""
+        tokenizer = self.get_tokenizer_group("prompts must be None if "
+                                             "skip_tokenizer_init is True")
+
+        return await tokenizer.encode_async(request_id=request_id,
+                                            prompt=prompt,
+                                            lora_request=lora_request)
+
+    async def _extract_prompt_components_async(
         self,
+        inputs: SingletonPromptInputs,
         request_id: str,
+        lora_request: Optional[LoRARequest] = None,
+    ) -> PromptComponents:
+        """Async version of :meth:`_extract_prompt_components`."""
+        if isinstance(inputs, str):
+            prompt = inputs
+            prompt_token_ids = await self._tokenize_prompt_async(
+                prompt,
+                request_id=request_id,
+                lora_request=lora_request,
+            )
+            multi_modal_data = None
+        elif isinstance(inputs, dict):
+            if "prompt_token_ids" in inputs:
+                prompt = None
+                prompt_token_ids = inputs["prompt_token_ids"]
+            else:
+                # NOTE: This extra assignment is required to pass mypy
+                prompt = parsed_prompt = inputs["prompt"]
+                prompt_token_ids = await self._tokenize_prompt_async(
+                    parsed_prompt,
+                    request_id=request_id,
+                    lora_request=lora_request,
+                )
+
+            multi_modal_data = inputs.get("multi_modal_data")
+        else:
+            assert_never(inputs)
+
+        return prompt, prompt_token_ids, multi_modal_data
+
+    async def _process_encoder_decoder_prompt_async(
+        self,
         inputs: PromptInputs,
+        request_id: str,
+    ) -> EncoderDecoderLLMInputs:
+        """Async version of :meth:`_process_encoder_decoder_prompt`."""
+        encoder_comps: PromptComponents
+        decoder_comps: DecoderPromptComponents
+
+        if is_explicit_encoder_decoder_prompt(inputs):
+            encoder_task = self._extract_prompt_components_async(
+                inputs["encoder_prompt"],
+                request_id=request_id,
+            )
+
+            if (decoder_input := inputs["decoder_prompt"]) is None:
+                encoder_comps = await encoder_task
+                decoder_comps = None, None, None
+            else:
+                decoder_task = self._extract_prompt_components_async(
+                    decoder_input,
+                    request_id=request_id,
+                )
+
+                encoder_comps, decoder_comps = await asyncio.gather(
+                    encoder_task, decoder_task)
+        else:
+            encoder_comps = await self._extract_prompt_components_async(
+                inputs,
+                request_id=request_id,
+            )
+
+            decoder_comps = None, None, None
+
+        return self._build_enc_dec_llm_inputs(encoder_comps, decoder_comps)
+
+    async def _process_decoder_only_prompt_async(
+        self,
+        inputs: SingletonPromptInputs,
+        request_id: str,
         lora_request: Optional[LoRARequest] = None,
         prompt_adapter_request: Optional[PromptAdapterRequest] = None,
     ) -> LLMInputs:
-        if isinstance(inputs, str):
-            inputs = {"prompt": inputs}
+        """Async version of :meth:`_process_decoder_only_prompt`."""
+        prompt_comps = await self._extract_prompt_components_async(
+            inputs,
+            request_id=request_id,
+            lora_request=lora_request,
+        )
 
-        if "prompt_token_ids" not in inputs:
-            tokenizer = self.get_tokenizer_group("prompts must be None if "
-                                                 "skip_tokenizer_init is True")
+        return self._build_decoder_only_llm_inputs(
+            prompt_comps,
+            prompt_adapter_request=prompt_adapter_request,
+        )
 
-            prompt_token_ids = await tokenizer.encode_async(
+    async def process_model_inputs_async(
+        self,
+        inputs: PromptInputs,
+        request_id: str,
+        lora_request: Optional[LoRARequest] = None,
+        prompt_adapter_request: Optional[PromptAdapterRequest] = None,
+    ) -> Union[LLMInputs, EncoderDecoderLLMInputs]:
+        """Async version of :meth:`process_model_inputs`."""
+        if self.is_encoder_decoder_model():
+            # Encoder-decoder model requires special mapping of
+            # input prompts to encoder & decoder
+            model_inputs = await self._process_encoder_decoder_prompt_async(
+                inputs,
                 request_id=request_id,
-                prompt=inputs["prompt"],
-                lora_request=lora_request)
+            )
         else:
-            prompt_token_ids = inputs["prompt_token_ids"]
+            if is_explicit_encoder_decoder_prompt(inputs):
+                raise ValueError("Cannot pass encoder-decoder prompt "
+                                 "to decoder-only models")
 
-        if prompt_adapter_request:
-            prompt_token_ids = [
-                0
-            ] * prompt_adapter_request.prompt_adapter_num_virtual_tokens + \
-                prompt_token_ids
-
-        llm_inputs = LLMInputs(prompt_token_ids=prompt_token_ids,
-                               prompt=inputs.get("prompt"),
-                               multi_modal_data=inputs.get("multi_modal_data"))
+            # Decoder-only operation
+            model_inputs = await self._process_decoder_only_prompt_async(
+                inputs,
+                request_id=request_id,
+                lora_request=lora_request,
+                prompt_adapter_request=prompt_adapter_request,
+            )
 
-        return self.input_processor(llm_inputs)
+        return self.input_processor(model_inputs)
 
     async def add_request_async(
         self,
@@ -336,6 +440,7 @@ class _AsyncLLMEngine(LLMEngine):
         trace_headers: Optional[Mapping[str, str]] = None,
         prompt_adapter_request: Optional[PromptAdapterRequest] = None,
     ) -> None:
+        """Async version of :meth:`add_request`."""
         if lora_request is not None and not self.lora_config:
             raise ValueError(f"Got lora_request {lora_request} but LoRA is "
                              "not enabled!")
@@ -343,10 +448,11 @@ class _AsyncLLMEngine(LLMEngine):
             arrival_time = time.time()
 
         processed_inputs = await self.process_model_inputs_async(
+            inputs,
             request_id=request_id,
-            inputs=inputs,
             lora_request=lora_request,
-            prompt_adapter_request=prompt_adapter_request)
+            prompt_adapter_request=prompt_adapter_request,
+        )
 
         self._add_processed_request(
             request_id=request_id,

vllm/engine/llm_engine.py

@@ -5,6 +5,8 @@ from typing import (TYPE_CHECKING, Any, ClassVar, Dict, Iterable, List,
 from typing import Sequence as GenericSequence
 from typing import Set, Tuple, Type, TypeVar, Union
 
+from typing_extensions import assert_never
+
 import vllm.envs as envs
 from vllm.config import (CacheConfig, DecodingConfig, DeviceConfig,
                          EngineConfig, LoadConfig, LoRAConfig, ModelConfig,
@@ -22,10 +24,12 @@ from vllm.engine.output_processor.stop_checker import StopChecker
 from vllm.engine.output_processor.util import create_output_by_sequence_group
 from vllm.executor.executor_base import ExecutorBase
 from vllm.executor.ray_utils import initialize_ray_cluster
-from vllm.inputs import (INPUT_REGISTRY, LLMInputs, PromptInputs,
-                         get_prompt_type)
+from vllm.inputs import (INPUT_REGISTRY, EncoderDecoderLLMInputs, LLMInputs,
+                         PromptInputs, SingletonPromptInputs)
+from vllm.inputs.parse import is_explicit_encoder_decoder_prompt
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
+from vllm.multimodal import MultiModalDataDict
 from vllm.outputs import (EmbeddingRequestOutput, RequestOutput,
                           RequestOutputFactory)
 from vllm.pooling_params import PoolingParams
@@ -43,8 +47,7 @@ from vllm.transformers_utils.tokenizer_group import (
     AnyTokenizer, BaseTokenizerGroup, init_tokenizer_from_configs)
 from vllm.usage.usage_lib import (UsageContext, is_usage_stats_enabled,
                                   usage_message)
-from vllm.utils import (Counter, is_embedding_model_config,
-                        is_encoder_decoder_model_config)
+from vllm.utils import Counter
 from vllm.version import __version__ as VLLM_VERSION
 
 logger = init_logger(__name__)
@@ -66,6 +69,11 @@ def _load_generation_config_dict(model_config: ModelConfig) -> Dict[str, Any]:
 
 _O = TypeVar("_O", RequestOutput, EmbeddingRequestOutput)
 
+PromptComponents = Tuple[Optional[str], List[int],
+                         Optional[MultiModalDataDict]]
+DecoderPromptComponents = Tuple[Optional[str], Optional[List[int]],
+                                Optional[MultiModalDataDict]]
+
 
 class LLMEngine:
     """An LLM engine that receives requests and generates texts.
@@ -524,7 +532,7 @@ class LLMEngine:
 
         return self.tokenizer.get_lora_tokenizer(lora_request).eos_token_id
 
-    def _get_decoder_start_token_id(self, ) -> Optional[int]:
+    def _get_decoder_start_token_id(self) -> Optional[int]:
         '''
         Obtain the decoder start token id employed by an encoder/decoder
         model. Returns None for non-encoder/decoder models or if the
@@ -553,7 +561,7 @@ class LLMEngine:
     def _add_processed_request(
         self,
         request_id: str,
-        processed_inputs: LLMInputs,
+        processed_inputs: Union[LLMInputs, EncoderDecoderLLMInputs],
         params: Union[SamplingParams, PoolingParams],
         arrival_time: float,
         lora_request: Optional[LoRARequest],
@@ -613,11 +621,11 @@ class LLMEngine:
     def stop_remote_worker_execution_loop(self) -> None:
         self.model_executor.stop_remote_worker_execution_loop()
 
-    _LLMInputComponentsType = Tuple[str, List[int], ]
+    _LLMInputComponentsType = Tuple[str, List[int]]
 
     def _prepare_decoder_input_ids_for_generation(
         self,
-        decoder_input_ids: Optional[List[int]] = None,
+        decoder_input_ids: Optional[List[int]],
     ) -> List[int]:
         """
         Prepares `decoder_input_ids` for generation with encoder-decoder models.
@@ -639,14 +647,13 @@ class LLMEngine:
         * Processed token list
         """
 
-        decoder_start_token_id: Optional[int] = (
-            self._get_decoder_start_token_id())
+        decoder_start_token_id = self._get_decoder_start_token_id()
         assert decoder_start_token_id is not None
 
         if decoder_input_ids is None:
             # no decoder prompt input ->
             # use decoder_start_token_id as decoder_input_ids
-            (decoder_input_ids) = self._get_default_enc_dec_decoder_prompt()
+            decoder_input_ids = self._get_default_enc_dec_decoder_prompt()
 
         if (len(decoder_input_ids) == 0
                 or decoder_input_ids[0] != decoder_start_token_id):
@@ -657,12 +664,11 @@ class LLMEngine:
     def _tokenize_prompt(
         self,
         prompt: str,
-        request_id: Optional[str] = None,
-        lora_request: Optional[str] = None,
+        request_id: str,
+        lora_request: Optional[LoRARequest],
     ) -> List[int]:
         '''
-        Wrapper around application of the model's
-        tokenizer.
+        Wrapper around application of the model's tokenizer.
 
         Arguments:
 
@@ -678,87 +684,72 @@ class LLMEngine:
         tokenizer = self.get_tokenizer_group("prompts must be None if "
                                              "skip_tokenizer_init is True")
 
-        prompt_token_ids = tokenizer.encode(request_id=request_id,
-                                            prompt=prompt,
-                                            lora_request=lora_request)
-
-        return prompt_token_ids
+        return tokenizer.encode(request_id=request_id,
+                                prompt=prompt,
+                                lora_request=lora_request)
 
-    def _extract_single_prompt_for_enc_dec_input(
+    def _extract_prompt_components(
         self,
-        inputs: Optional[PromptInputs],
-        request_id: Optional[str] = None,
-        ptype: Optional[str] = None,
-        is_encoder_prompt: bool = False,
-    ) -> Tuple[Optional[str], List[int]]:
+        inputs: SingletonPromptInputs,
+        request_id: str,
+        lora_request: Optional[LoRARequest] = None,
+    ) -> PromptComponents:
         '''
-        Only for encoder/decoder models:
-        Extract prompt & prompt_token_ids from any single
-        encoder or decoder input prompt. For encoder input prompts
-        in particular, also extract multi-modal data.
-
-        This function handles the following scenarios:
-        1. The user supplied a singleton encoder prompt
-          & the prompt/prompt-token-ids must be extracted.
-        2. The user supplied an explicit encoder/decoder
-          prompt & the prompt/prompt-token-ids must be
-          extracted from either the encoder and decoder prompts.
-
-        For decoder prompts in particular (scenario 2), special
-        processing is applied to the returned decoder token ids.
+        Extract the components of any single encoder or decoder input prompt.
 
         Arguments:
 
         * request_id
-        * ptype: str representation of the input prompt type.
-                 If `ptype` is `None`, assume that the prompt
-                 type is unknown and must be inferred. This is the
-                 case for ExplicitEncoderDecoder sub-prompts.
         * inputs: single encoder or decoder input prompt
-        * is_encoder_prompt: True if encoder input prompt.
-                             If False, decoder prompt tokens
-                             are preprocessed.
+        * lora_request: this is only valid for decoder prompts
 
         Returns:
 
         * prompt
         * prompt_token_ids
+        * multi_modal_data
         '''
-        prompt_token_ids = None
-        ptype = (get_prompt_type(inputs) if ptype is None else ptype)
 
-        if inputs is None:
-            prompt = None
-        elif ptype == 'str':
+        if isinstance(inputs, str):
             prompt = inputs
             prompt_token_ids = self._tokenize_prompt(
                 prompt,
                 request_id=request_id,
+                lora_request=lora_request,
             )
-        elif ptype == 'TokensPrompt':
-            prompt = None
-            prompt_token_ids = inputs['prompt_token_ids']
+            multi_modal_data = None
+        elif isinstance(inputs, dict):
+            if "prompt_token_ids" in inputs:
+                prompt = None
+                prompt_token_ids = inputs["prompt_token_ids"]
+            else:
+                # NOTE: This extra assignment is required to pass mypy
+                prompt = parsed_prompt = inputs["prompt"]
+                prompt_token_ids = self._tokenize_prompt(
+                    parsed_prompt,
+                    request_id=request_id,
+                    lora_request=lora_request,
+                )
+
+            multi_modal_data = inputs.get("multi_modal_data")
         else:
-            prompt = inputs['prompt']
-            prompt_token_ids = self._tokenize_prompt(
-                prompt,
-                request_id=request_id,
-            )
+            assert_never(inputs)
 
-        if not is_encoder_prompt:
-            # Apply special pre-processing to
-            # decoder prompts
-            prompt_token_ids = (self._prepare_decoder_input_ids_for_generation(
-                prompt_token_ids, ))
+        return prompt, prompt_token_ids, multi_modal_data
 
-        assert prompt_token_ids is not None
+    def _apply_prompt_adapter(
+        self,
+        prompt_token_ids: List[int],
+        prompt_adapter_request: Optional[PromptAdapterRequest],
+    ) -> List[int]:
+        if prompt_adapter_request:
+            prompt_token_ids = (
+                [0] * prompt_adapter_request.prompt_adapter_num_virtual_tokens
+                + prompt_token_ids)
 
-        return (
-            prompt,
-            prompt_token_ids,
-        )
+        return prompt_token_ids
 
-    def _get_default_enc_dec_decoder_prompt(self, ) -> List[int]:
+    def _get_default_enc_dec_decoder_prompt(self) -> List[int]:
         '''
         Specifically for encoder/decoder models:
         generate a default decoder prompt for when
@@ -792,18 +783,39 @@ class LLMEngine:
 
         bos_token_id = self._get_bos_token_id()
         assert bos_token_id is not None
-        prompt_token_ids: List[int] = [bos_token_id]
-        return prompt_token_ids
+        return [bos_token_id]
+
+    def _build_enc_dec_llm_inputs(
+        self,
+        encoder_comps: PromptComponents,
+        decoder_comps: DecoderPromptComponents,
+    ) -> EncoderDecoderLLMInputs:
+        encoder_prompt, encoder_prompt_ids, encoder_mm_data = encoder_comps
+        decoder_prompt, decoder_prompt_ids, decoder_mm_data = decoder_comps
+
+        if encoder_mm_data is not None or decoder_mm_data is not None:
+            raise ValueError("Multi-modal encoder-decoder models are "
+                             "not supported yet")
+
+        decoder_prompt_ids = (
+            self._prepare_decoder_input_ids_for_generation(decoder_prompt_ids))
+
+        return EncoderDecoderLLMInputs(
+            prompt_token_ids=decoder_prompt_ids,
+            prompt=decoder_prompt,
+            encoder_prompt_token_ids=encoder_prompt_ids,
+            encoder_prompt=encoder_prompt,
+        )
 
     def _process_encoder_decoder_prompt(
         self,
         inputs: PromptInputs,
-        request_id: Optional[str] = None,
-    ) -> LLMInputs:
+        request_id: str,
+    ) -> EncoderDecoderLLMInputs:
         '''
         For encoder/decoder models only:
-        Process an input prompt
-        into an `LLMInputs` instance.
+        Process an input prompt into an
+        :class:`EncoderDecoderLLMInputs` instance.
 
         There are two types of input prompts:
         singleton prompts which carry only the
@@ -830,136 +842,103 @@ class LLMEngine:
 
         Returns:
 
-        * `LLMInputs` instance
+        * :class:`EncoderDecoderLLMInputs` instance
         '''
 
-        ptype = get_prompt_type(inputs)
-
-        # Obtain encoder and decoder prompt tokens. Note
-        # that, no matter what, the decoder
-        # prompt type is unknown.
-        if ptype == "ExplicitEncoderDecoder":
-            # If input is explicit encoder/decoder prompt,
-            # then it remains to be determined what type
-            # of encoder prompt we have
-            extracted_encoder_prompt = inputs.get('encoder_prompt')
-            encoder_ptype = None
-            # Extract decoder prompt from explicit
-            # encoder/decoder prompt
-            extracted_decoder_prompt = inputs.get('decoder_prompt')
+        encoder_comps: PromptComponents
+        decoder_comps: DecoderPromptComponents
+
+        if is_explicit_encoder_decoder_prompt(inputs):
+            encoder_comps = self._extract_prompt_components(
+                inputs["encoder_prompt"],
+                request_id=request_id,
+            )
+
+            if (decoder_input := inputs["decoder_prompt"]) is None:
+                decoder_comps = None, None, None
+            else:
+                decoder_comps = self._extract_prompt_components(
+                    decoder_input,
+                    request_id=request_id,
+                )
         else:
-            # If input is singleton encoder prompt, then
-            # we know the encoder prompt type
-            extracted_encoder_prompt = inputs
-            encoder_ptype = ptype
-            # Decoder prompt is always unknown if
-            # encoder/decoder prompt is not explicit
-            extracted_decoder_prompt = None
-
-        # Invoke helper function to obtain encoder
-        # prompt and prompt token ids, either from
-        # singleton encoder prompt or from the
-        # encoder sub-prompt of an explicit
-        # encoder/decode scenario 2), special
-        # processing is applied to the returned decoder token ids
-        (
-            encoder_prompt,
-            encoder_prompt_token_ids,
-        ) = self._extract_single_prompt_for_enc_dec_input(
-            extracted_encoder_prompt,
-            request_id=request_id,
-            ptype=encoder_ptype,
-            is_encoder_prompt=True,
-        )
+            encoder_comps = self._extract_prompt_components(
+                inputs,
+                request_id=request_id,
+            )
 
-        # Invoke helper method to obtain
-        # decoder prompt and prompt token ids.
-        #
-        # The helper method will detect the decoder
-        # prompt type.
-        #
-        # Helper method will also apply special
-        # preprocessing unique to decoder prompts.
-        (
-            decoder_prompt,
-            decoder_prompt_token_ids,
-        ) = self._extract_single_prompt_for_enc_dec_input(
-            extracted_decoder_prompt,
-            request_id=request_id,
-            ptype=None,
-            is_encoder_prompt=False,
-        )
+            decoder_comps = None, None, None
 
-        return LLMInputs(
-            prompt_token_ids=decoder_prompt_token_ids,
-            prompt=decoder_prompt,
-            encoder_prompt_token_ids=encoder_prompt_token_ids,
-            encoder_prompt=encoder_prompt,
-        )
+        return self._build_enc_dec_llm_inputs(encoder_comps, decoder_comps)
+
+    def _build_decoder_only_llm_inputs(
+        self,
+        prompt_comps: PromptComponents,
+        prompt_adapter_request: Optional[PromptAdapterRequest],
+    ) -> LLMInputs:
+        prompt, prompt_token_ids, multi_modal_data = prompt_comps
+
+        prompt_token_ids = self._apply_prompt_adapter(
+            prompt_token_ids, prompt_adapter_request=prompt_adapter_request)
+
+        return LLMInputs(prompt_token_ids=prompt_token_ids,
+                         prompt=prompt,
+                         multi_modal_data=multi_modal_data)
 
     def _process_decoder_only_prompt(
         self,
-        inputs: PromptInputs,
+        inputs: SingletonPromptInputs,
+        request_id: str,
         lora_request: Optional[LoRARequest] = None,
-        request_id: Optional[str] = None,
         prompt_adapter_request: Optional[PromptAdapterRequest] = None,
     ) -> LLMInputs:
         '''
         For decoder-only models:
-        Process an input prompt
-        into an `LLMInputs` instance.
+        Process an input prompt into an :class:`LLMInputs` instance.
 
         Arguments:
 
         * inputs: input prompt
-        * lora_request
         * request_id
+        * lora_request
         * prompt_adapter_request
 
         Returns:
 
-        * `LLMInputs` instance
+        * :class:`LLMInputs` instance
         '''
 
-        if isinstance(inputs, str):
-            inputs = {"prompt": inputs}
-        prompt = inputs.get("prompt")
-
-        if "prompt_token_ids" not in inputs:
-            prompt_token_ids = self._tokenize_prompt(
-                prompt,
-                request_id=request_id,
-                lora_request=lora_request,
-            )
-        else:
-            prompt_token_ids = inputs["prompt_token_ids"]
-
-        if prompt_adapter_request:
-            prompt_token_ids = (
-                [0] * prompt_adapter_request.prompt_adapter_num_virtual_tokens
-                + prompt_token_ids)
+        prompt_comps = self._extract_prompt_components(
+            inputs,
+            request_id=request_id,
+            lora_request=lora_request,
+        )
 
-        return LLMInputs(prompt_token_ids=prompt_token_ids,
-                         prompt=prompt,
-                         multi_modal_data=inputs.get("multi_modal_data"))
+        return self._build_decoder_only_llm_inputs(
+            prompt_comps,
+            prompt_adapter_request=prompt_adapter_request,
+        )
 
     def process_model_inputs(
         self,
-        request_id: str,
         inputs: PromptInputs,
+        request_id: str,
         lora_request: Optional[LoRARequest] = None,
         prompt_adapter_request: Optional[PromptAdapterRequest] = None,
-    ) -> LLMInputs:
+    ) -> Union[LLMInputs, EncoderDecoderLLMInputs]:
 
         if self.is_encoder_decoder_model():
             # Encoder-decoder model requires special mapping of
             # input prompts to encoder & decoder
-
             model_inputs = self._process_encoder_decoder_prompt(
                 inputs,
                 request_id=request_id,
             )
         else:
+            if is_explicit_encoder_decoder_prompt(inputs):
+                raise ValueError("Cannot pass encoder-decoder prompt "
+                                 "to decoder-only models")
+
             # Decoder-only operation
             model_inputs = self._process_decoder_only_prompt(
                 inputs,
@@ -1029,10 +1008,11 @@ class LLMEngine:
             arrival_time = time.time()
 
         processed_inputs = self.process_model_inputs(
+            inputs,
             request_id=request_id,
-            inputs=inputs,
             lora_request=lora_request,
-            prompt_adapter_request=prompt_adapter_request)
+            prompt_adapter_request=prompt_adapter_request,
+        )
 
         self._add_processed_request(
             request_id=request_id,
@@ -1597,7 +1577,7 @@ class LLMEngine:
             seq_span.set_attribute(SpanAttributes.LLM_LATENCY_E2E, e2e_time)
 
     def is_encoder_decoder_model(self):
-        return is_encoder_decoder_model_config(self.model_config)
+        return self.model_config.is_encoder_decoder_model
 
     def is_embedding_model(self):
-        return is_embedding_model_config(self.model_config)
+        return self.model_config.is_embedding_model

vllm/entrypoints/chat_utils.py

@@ -2,8 +2,7 @@ import codecs
 from dataclasses import dataclass
 from functools import lru_cache
 from pathlib import Path
-from typing import (Any, Awaitable, Iterable, List, Optional, Tuple, Union,
-                    cast, final)
+from typing import Any, Awaitable, Iterable, List, Optional, Tuple, Union, cast
 
 # yapf conflicts with isort for this block
 # yapf: disable
@@ -59,7 +58,7 @@ ChatCompletionMessageParam = Union[OpenAIChatCompletionMessageParam,
                                    CustomChatCompletionMessageParam]
 
 
-@final  # So that it should be compatible with Dict[str, str]
+# TODO: Make fields ReadOnly once mypy supports it
 class ConversationMessage(TypedDict):
     role: str
     content: str

vllm/entrypoints/llm.py

@@ -6,8 +6,8 @@ from transformers import PreTrainedTokenizer, PreTrainedTokenizerFast
 
 from vllm.engine.arg_utils import EngineArgs
 from vllm.engine.llm_engine import LLMEngine
-from vllm.inputs import (PromptInputs, TextPrompt, TokensPrompt,
-                         parse_and_batch_prompt)
+from vllm.inputs import PromptInputs, TextPrompt, TokensPrompt
+from vllm.inputs.parse import parse_and_batch_prompt
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.model_executor.guided_decoding import (

vllm/entrypoints/openai/logits_processors.py

@@ -40,9 +40,11 @@ def _get_allowed_token_ids_logits_processor(
     return AllowedTokenIdsLogitsProcessor(allowed_token_ids)
 
 
-def logit_bias_logits_processor(logit_bias: Dict[str,
-                                                 float], token_ids: List[int],
-                                logits: torch.Tensor) -> torch.Tensor:
+def logit_bias_logits_processor(
+    logit_bias: Dict[int, float],
+    token_ids: List[int],
+    logits: torch.Tensor,
+) -> torch.Tensor:
     for token_id, bias in logit_bias.items():
         logits[token_id] += bias
     return logits

vllm/entrypoints/openai/serving_engine.py

@@ -22,7 +22,7 @@ from vllm.entrypoints.openai.protocol import (ChatCompletionRequest,
                                               TokenizeCompletionRequest,
                                               TokenizeRequest)
 # yapf: enable
-from vllm.inputs import parse_and_batch_prompt
+from vllm.inputs.parse import parse_and_batch_prompt
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.model_executor.guided_decoding import (

vllm/inputs/__init__.py

-from .data import (ExplicitEncoderDecoderPrompt, LLMInputs, ParsedText,
-                   ParsedTokens, PromptInputs, SingletonPromptInputs,
-                   TextPrompt, TokensPrompt, get_prompt_type,
-                   is_valid_encoder_decoder_llm_inputs, parse_and_batch_prompt)
+from .data import (EncoderDecoderLLMInputs, ExplicitEncoderDecoderPrompt,
+                   LLMInputs, PromptInputs, SingletonPromptInputs, TextPrompt,
+                   TokensPrompt, build_explicit_enc_dec_prompt,
+                   to_enc_dec_tuple_list, zip_enc_dec_prompts)
 from .registry import InputContext, InputRegistry
 
 INPUT_REGISTRY = InputRegistry()
@@ -14,18 +14,17 @@ See also:
 """
 
 __all__ = [
-    "ParsedText",
-    "ParsedTokens",
-    "parse_and_batch_prompt",
     "TextPrompt",
     "TokensPrompt",
     "PromptInputs",
+    "SingletonPromptInputs",
+    "ExplicitEncoderDecoderPrompt",
     "LLMInputs",
+    "EncoderDecoderLLMInputs",
+    "build_explicit_enc_dec_prompt",
+    "to_enc_dec_tuple_list",
+    "zip_enc_dec_prompts",
     "INPUT_REGISTRY",
     "InputContext",
     "InputRegistry",
-    "get_prompt_type",
-    "is_valid_encoder_decoder_llm_inputs",
-    "ExplicitEncoderDecoderPrompt",
-    "SingletonPromptInputs",
 ]

vllm/inputs/data.py

-from typing import (TYPE_CHECKING, List, Literal, Optional, Sequence,
-                    TypedDict, Union, cast, overload)
+from typing import (TYPE_CHECKING, Generic, Iterable, List, Optional, Tuple,
+                    Union)
 
-from typing_extensions import NotRequired
+from typing_extensions import NotRequired, TypedDict, TypeVar
 
 if TYPE_CHECKING:
     from vllm.multimodal import MultiModalDataDict
 
 
-class ParsedText(TypedDict):
-    content: str
-    is_tokens: Literal[False]
-
-
-class ParsedTokens(TypedDict):
-    content: List[int]
-    is_tokens: Literal[True]
-
-
-# https://github.com/vllm-project/vllm/pull/4028
-@overload
-def parse_and_batch_prompt(
-        prompt: Union[str, List[str]]) -> Sequence[ParsedText]:
-    ...
-
-
-@overload
-def parse_and_batch_prompt(
-        prompt: Union[List[int], List[List[int]]]) -> Sequence[ParsedTokens]:
-    ...
-
-
-def parse_and_batch_prompt(
-    prompt: Union[str, List[str], List[int], List[List[int]]],
-) -> Union[Sequence[ParsedText], Sequence[ParsedTokens]]:
-    if isinstance(prompt, str):
-        # case 1: a string
-        return [ParsedText(content=prompt, is_tokens=False)]
-
-    if isinstance(prompt, list):
-        if len(prompt) == 0:
-            raise ValueError("please provide at least one prompt")
-
-        if isinstance(prompt[0], str):
-            # case 2: array of strings
-            return [
-                ParsedText(content=elem, is_tokens=False)
-                for elem in cast(List[str], prompt)
-            ]
-        if isinstance(prompt[0], int):
-            # case 3: array of tokens
-            elem = cast(List[int], prompt)
-            return [ParsedTokens(content=elem, is_tokens=True)]
-        if isinstance(prompt[0], list):
-            if len(prompt[0]) == 0:
-                raise ValueError("please provide at least one prompt")
-
-            if isinstance(prompt[0][0], int):
-                # case 4: array of token arrays
-                return [
-                    ParsedTokens(content=elem, is_tokens=True)
-                    for elem in cast(List[List[int]], prompt)
-                ]
-
-    raise ValueError("prompt must be a string, array of strings, "
-                     "array of tokens, or array of token arrays")
-
-
 class TextPrompt(TypedDict):
     """Schema for a text prompt."""
 
@@ -103,39 +44,49 @@ Note that "singleton" is as opposed to a data structure
 which encapsulates multiple prompts, i.e. of the sort
 which may be utilized for encoder/decoder models when
 the user desires to express both the encoder & decoder
-prompts explicitly, i.e. ExplicitEncoderDecoderPrompt
+prompts explicitly, i.e. :class:`ExplicitEncoderDecoderPrompt`
 
-A prompt of type SingletonPromptInputs may be employed
+A prompt of type :class:`SingletonPromptInputs` may be employed
 as (1) input to a decoder-only model, (2) input to
 the encoder of an encoder/decoder model, in the scenario
 where the decoder-prompt is not specified explicitly, or
 (3) as a member of a larger data structure encapsulating
-more than one prompt, i.e. ExplicitEncoderDecoderPrompt
+more than one prompt, i.e. :class:`ExplicitEncoderDecoderPrompt`
 """
 
+_T1_co = TypeVar("_T1_co",
+                 bound=SingletonPromptInputs,
+                 default=SingletonPromptInputs,
+                 covariant=True)
+_T2_co = TypeVar("_T2_co",
+                 bound=SingletonPromptInputs,
+                 default=SingletonPromptInputs,
+                 covariant=True)
 
-class ExplicitEncoderDecoderPrompt(TypedDict):
+
+# TODO: Make fields ReadOnly once mypy supports it
+class ExplicitEncoderDecoderPrompt(TypedDict, Generic[_T1_co, _T2_co]):
     """Represents an encoder/decoder model input prompt,
     comprising an explicit encoder prompt and a 
     decoder prompt.
 
     The encoder and decoder prompts, respectively,
     may formatted according to any of the
-    SingletonPromptInputs schemas, and are not
+    :class:`SingletonPromptInputs` schemas, and are not
     required to have the same schema.
 
     Only the encoder prompt may have multi-modal data.
 
-    Note that an ExplicitEncoderDecoderPrompt may not
+    Note that an :class:`ExplicitEncoderDecoderPrompt` may not
     be used as an input to a decoder-only model,
     and that the `encoder_prompt` and `decoder_prompt`
-    fields of this data structure may not themselves
-    must be SingletonPromptInputs instances.
+    fields of this data structure themselves must be
+    :class:`SingletonPromptInputs` instances.
     """
 
-    encoder_prompt: SingletonPromptInputs
+    encoder_prompt: _T1_co
 
-    decoder_prompt: SingletonPromptInputs
+    decoder_prompt: Optional[_T2_co]
 
 
 PromptInputs = Union[SingletonPromptInputs, ExplicitEncoderDecoderPrompt]
@@ -150,60 +101,12 @@ both decoder-only and encoder/decoder input types:
 """
 
 
-def _has_required_keys(
-    d: dict,
-    required_keys: set,
-) -> bool:
-    return required_keys.issubset(d.keys())
-
-
-def get_prompt_type(prompt: Optional[PromptInputs]) -> Optional[str]:
-    """
-    Get the type-name of the prompt argument instance, given that
-    isinstance() cannot apply to TypedDict subclasses directly.
-    If the prompt is None, return 'None' as the type name.
-
-    Arguments:
-
-    * prompt: LLM input prompt or None
-
-    Returns:
-
-    * String representation of prompt type
-    """
-
-    if prompt is None:
-        return 'None'
-
-    required_keys_dict = {
-        'TextPrompt': {'prompt'},
-        'TokensPrompt': {'prompt_token_ids'},
-        'ExplicitEncoderDecoder': {'encoder_prompt', 'decoder_prompt'},
-    }
-
-    if isinstance(prompt, dict):
-        for (ptype, required_keys) in required_keys_dict.items():
-            # Ignore type checking in the conditional below because type
-            # checker does not understand that is_dict(prompt) narrows
-            # down the possible types
-            if _has_required_keys(
-                    prompt,  # type: ignore
-                    required_keys):
-                return ptype
-
-        raise ValueError(f"Invalid prompt {prompt}, valid types are "
-                         "required_keys_dict={required_keys_dict}")
-
-    if isinstance(prompt, str):
-        return "str"
-
-    raise ValueError(f"Invalid prompt {prompt}")
-
-
 class LLMInputs(TypedDict):
     """
     The inputs in :class:`~vllm.LLMEngine` before they are
     passed to the model executor.
+
+    This specifies the data required for decoder-only models.
     """
     prompt_token_ids: List[int]
     """The token IDs of the prompt."""
@@ -213,7 +116,21 @@ class LLMInputs(TypedDict):
     The original prompt text corresponding to the token IDs, if available.
     """
 
-    encoder_prompt_token_ids: NotRequired[List[int]]
+    multi_modal_data: NotRequired[Optional["MultiModalDataDict"]]
+    """
+    Optional multi-modal data to pass to the model,
+    if the model supports it.
+    """
+
+
+class EncoderDecoderLLMInputs(LLMInputs):
+    """
+    The inputs in :class:`~vllm.LLMEngine` before they are
+    passed to the model executor.
+
+    This specifies the required data for encoder-decoder models.
+    """
+    encoder_prompt_token_ids: List[int]
     """The token IDs of the encoder prompt."""
 
     encoder_prompt: NotRequired[Optional[str]]
@@ -222,20 +139,40 @@ class LLMInputs(TypedDict):
     available.
     """
 
-    multi_modal_data: NotRequired[Optional["MultiModalDataDict"]]
-    """
-    Optional multi-modal data to pass to the model,
-    if the model supports it.
-    """
+
+_T1 = TypeVar("_T1",
+              bound=SingletonPromptInputs,
+              default=SingletonPromptInputs)
+_T2 = TypeVar("_T2",
+              bound=SingletonPromptInputs,
+              default=SingletonPromptInputs)
 
 
-def is_valid_encoder_decoder_llm_inputs(inputs: LLMInputs) -> bool:
+def build_explicit_enc_dec_prompt(
+    encoder_prompt: _T1,
+    decoder_prompt: Optional[_T2],
+) -> ExplicitEncoderDecoderPrompt[_T1, _T2]:
+    return ExplicitEncoderDecoderPrompt(encoder_prompt=encoder_prompt,
+                                        decoder_prompt=decoder_prompt)
+
+
+def zip_enc_dec_prompts(
+    enc_prompts: Iterable[_T1],
+    dec_prompts: Iterable[Optional[_T2]],
+) -> List[ExplicitEncoderDecoderPrompt[_T1, _T2]]:
     """
-    Return True if the LLMInputs instance has the correct configuration
-    for encoder/decoder.
+    Zip encoder and decoder prompts together into a list of
+    :class:`ExplicitEncoderDecoderPrompt` instances.
     """
+    return [
+        build_explicit_enc_dec_prompt(encoder_prompt, decoder_prompt)
+        for (encoder_prompt, decoder_prompt) in zip(enc_prompts, dec_prompts)
+    ]
+
 
-    # True if encoder prompt token ids field exists &
-    # is not None
-    return ('encoder_prompt_token_ids' in inputs
-            and inputs['encoder_prompt_token_ids'] is not None)
+def to_enc_dec_tuple_list(
+    enc_dec_prompts: Iterable[ExplicitEncoderDecoderPrompt[_T1, _T2]],
+) -> List[Tuple[_T1, Optional[_T2]]]:
+    return [(enc_dec_prompt["encoder_prompt"],
+             enc_dec_prompt["decoder_prompt"])
+            for enc_dec_prompt in enc_dec_prompts]

vllm/inputs/parse.py

+from typing import List, Literal, Sequence, TypedDict, Union, overload
+
+from typing_extensions import TypeIs
+
+from vllm.utils import is_list_of
+
+from .data import (EncoderDecoderLLMInputs, ExplicitEncoderDecoderPrompt,
+                   LLMInputs, PromptInputs)
+
+
+class ParsedText(TypedDict):
+    content: str
+    is_tokens: Literal[False]
+
+
+class ParsedTokens(TypedDict):
+    content: List[int]
+    is_tokens: Literal[True]
+
+
+@overload
+def parse_and_batch_prompt(
+        prompt: Union[str, List[str]]) -> Sequence[ParsedText]:
+    ...
+
+
+@overload
+def parse_and_batch_prompt(
+        prompt: Union[List[int], List[List[int]]]) -> Sequence[ParsedTokens]:
+    ...
+
+
+def parse_and_batch_prompt(
+    prompt: Union[str, List[str], List[int], List[List[int]]],
+) -> Union[Sequence[ParsedText], Sequence[ParsedTokens]]:
+    if isinstance(prompt, str):
+        # case 1: a string
+        return [ParsedText(content=prompt, is_tokens=False)]
+
+    if isinstance(prompt, list):
+        if len(prompt) == 0:
+            raise ValueError("please provide at least one prompt")
+
+        if is_list_of(prompt, str):
+            # case 2: array of strings
+            return [
+                ParsedText(content=elem, is_tokens=False) for elem in prompt
+            ]
+        if is_list_of(prompt, int):
+            # case 3: array of tokens
+            return [ParsedTokens(content=prompt, is_tokens=True)]
+        if is_list_of(prompt, list):
+            if len(prompt[0]) == 0:
+                raise ValueError("please provide at least one prompt")
+
+            if is_list_of(prompt[0], int):
+                # case 4: array of token arrays
+                return [
+                    ParsedTokens(content=elem, is_tokens=True)
+                    for elem in prompt
+                ]
+
+    raise ValueError("prompt must be a string, array of strings, "
+                     "array of tokens, or array of token arrays")
+
+
+def is_explicit_encoder_decoder_prompt(
+        inputs: PromptInputs) -> TypeIs[ExplicitEncoderDecoderPrompt]:
+    return isinstance(inputs, dict) and "encoder_prompt" in inputs
+
+
+def is_valid_encoder_decoder_llm_inputs(
+    inputs: Union[LLMInputs, EncoderDecoderLLMInputs],
+) -> TypeIs[EncoderDecoderLLMInputs]:
+    return "encoder_prompt_token_ids" in inputs