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vllm/vllm/parser/abstract_parser.py
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ChaunceyGitHubcjackalmergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
2043258dec [Frontend] Support strict mode for tool calling (#45003)
Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>
Co-authored-by: cjackal <44624812+cjackal@users.noreply.github.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
2026-06-12 07:51:48 +00:00

789 lines
28 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import contextlib
import json
from abc import abstractmethod
from collections.abc import Sequence
from dataclasses import dataclass, field
from functools import cached_property
from openai.types.responses import ToolChoiceFunction
from pydantic import TypeAdapter, ValidationError
from vllm.entrypoints.openai.chat_completion.protocol import (
ChatCompletionNamedToolChoiceParam,
ChatCompletionRequest,
)
from vllm.entrypoints.openai.engine.protocol import (
DeltaMessage,
ExtractedToolCallInformation,
FunctionCall,
FunctionDefinition,
)
from vllm.entrypoints.openai.responses.protocol import ResponsesRequest
from vllm.logger import init_logger
from vllm.parser.metrics import record_tool_parser_invocation
from vllm.reasoning.abs_reasoning_parsers import ReasoningParser
from vllm.sampling_params import StructuredOutputsParams
from vllm.tokenizers import TokenizerLike
from vllm.tool_parsers.abstract_tool_parser import Tool, ToolParser
from vllm.tool_parsers.streaming import (
extract_named_tool_call_streaming,
extract_required_tool_call_streaming,
)
logger = init_logger(__name__)
@dataclass
class StreamState:
"""Mutable state for ``Parser.parse_delta()``. One per stream."""
reasoning_ended: bool = False
tool_call_text_started: bool = False
prompt_reasoning_checked: bool = False
previous_text: str = ""
previous_token_ids: list[int] = field(default_factory=list)
history_tool_call_cnt: int = 0
tool_call_id_type: str = "random"
# only used for "required" and "named tool" choices,
# tracks whether function name has been fully returned in the stream yet
function_name_returned: bool = False
class Parser:
"""
Abstract Parser class that unifies ReasoningParser and ToolParser into
a single interface for parsing model output.
This class provides a unified way to handle both reasoning extraction
(e.g., chain-of-thought content in <think> tags) and tool call extraction
(e.g., function calls in XML/JSON format) from model outputs.
Subclasses can either:
1. Override the abstract methods directly for custom parsing logic
2. Set `reasoning_parser` and `tool_parser` properties to delegate to
existing parser implementations
Class Attributes:
reasoning_parser_cls: The ReasoningParser class to use (for compatibility
with code that needs the class, not instance).
tool_parser_cls: The ToolParser class to use (for compatibility with
code that needs the class, not instance).
"""
# Class-level parser classes for compatibility with existing patterns
# Subclasses should override these if they use specific parser classes
reasoning_parser_cls: type[ReasoningParser] | None = None
tool_parser_cls: type[ToolParser] | None = None
def __init__(
self,
tokenizer: TokenizerLike,
tools: list[Tool] | None = None,
*args,
**kwargs,
):
self.model_tokenizer = tokenizer
self._reasoning_parser: ReasoningParser | None = None
self._tool_parser: ToolParser | None = None
self._stream_state = StreamState()
if self.__class__.reasoning_parser_cls is not None:
self._reasoning_parser = self.__class__.reasoning_parser_cls(
tokenizer, *args, **kwargs
)
if self.__class__.tool_parser_cls is not None:
self._tool_parser = self.__class__.tool_parser_cls(tokenizer, tools)
@cached_property
def vocab(self) -> dict[str, int]:
"""Get the vocabulary mapping from tokens to IDs."""
return self.model_tokenizer.get_vocab()
@property
def reasoning_parser(self) -> ReasoningParser | None:
"""The underlying reasoning parser, if any."""
return self._reasoning_parser
@reasoning_parser.setter
def reasoning_parser(self, parser: ReasoningParser | None) -> None:
self._reasoning_parser = parser
@property
def tool_parser(self) -> ToolParser | None:
"""The underlying tool parser, if any."""
return self._tool_parser
@tool_parser.setter
def tool_parser(self, parser: ToolParser | None) -> None:
self._tool_parser = parser
# ========== Reasoning Parser Methods ==========
@abstractmethod
def is_reasoning_end(self, input_ids: list[int]) -> bool:
"""
Check if the reasoning content ends in the input_ids.
Used by structured engines like `xgrammar` to check if the
reasoning content ends in the model output.
Args:
input_ids: The token IDs of the model output.
Returns:
True if the reasoning content ends in the input_ids.
"""
def is_reasoning_end_streaming(
self, input_ids: list[int], delta_ids: list[int]
) -> bool:
"""
Check if the reasoning content ends during a decode step.
Args:
input_ids: The entire model output token IDs.
delta_ids: The last few computed tokens at the current decode step.
Returns:
True if the reasoning content ends in the delta_ids.
"""
return self.is_reasoning_end(input_ids)
@abstractmethod
def extract_content_ids(self, input_ids: list[int]) -> list[int]:
"""
Extract content token IDs from the input_ids.
This extracts the non-reasoning content (e.g., everything after
the </think> tag).
Args:
input_ids: The token IDs of the model output.
Returns:
The extracted content token IDs.
"""
@abstractmethod
def extract_reasoning(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
) -> tuple[str | None, str | None]:
"""
Extract reasoning content from a complete model-generated string.
Used for non-streaming responses where we have the entire model
response available before sending to the client.
Args:
model_output: The complete model-generated string.
request: The request object used to generate the output.
Returns:
A tuple of (reasoning, response_content).
"""
@abstractmethod
def extract_reasoning_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
) -> DeltaMessage | None:
"""
Extract reasoning content from a streaming delta message.
Args:
previous_text: Text from all previous tokens.
current_text: Text including the current delta.
delta_text: The new text in this delta.
previous_token_ids: Token IDs from previous generation.
current_token_ids: All token IDs including current.
delta_token_ids: The new token IDs in this delta.
Returns:
A DeltaMessage with reasoning and/or content fields, or None.
"""
# ========== Tool Parser Methods ==========
def adjust_request(
self, request: ChatCompletionRequest | ResponsesRequest
) -> ChatCompletionRequest | ResponsesRequest:
"""
Adjust the request parameters for tool calling.
Can be overridden by subclasses to modify request parameters
(e.g., setting structured output schemas for tool calling).
Args:
request: The original request.
Returns:
The adjusted request.
"""
return request
@abstractmethod
def extract_tool_calls(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
) -> ExtractedToolCallInformation:
"""
Extract tool calls from a complete model-generated string.
Used for non-streaming responses.
Args:
model_output: The complete model-generated string.
request: The request object used to generate the output.
Returns:
ExtractedToolCallInformation containing the tool calls.
"""
@abstractmethod
def extract_tool_calls_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
request: ChatCompletionRequest | ResponsesRequest,
) -> DeltaMessage | None:
"""
Extract tool calls from a streaming delta message.
Args:
previous_text: Text from all previous tokens.
current_text: Text including the current delta.
delta_text: The new text in this delta.
previous_token_ids: Token IDs from previous generation.
current_token_ids: All token IDs including current.
delta_token_ids: The new token IDs in this delta.
request: The request object.
Returns:
A DeltaMessage with tool_calls field, or None.
"""
@abstractmethod
def parse(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
enable_auto_tools: bool = False,
model_output_token_ids: Sequence[int] = (),
) -> tuple[str | None, str | None, list[FunctionCall] | None]:
"""Parse a complete model output, extracting reasoning and tool calls.
Args:
model_output: The complete model-generated string.
request: The request object used to generate the output.
enable_auto_tools: Whether to enable automatic tool call parsing.
model_output_token_ids: The generated raw output token IDs.
Returns:
A tuple of (reasoning, content, tool_calls).
"""
@abstractmethod
def parse_delta(
self,
delta_text: str,
delta_token_ids: list[int],
request: ChatCompletionRequest | ResponsesRequest,
prompt_token_ids: list[int] | None = None,
*,
finished: bool,
) -> DeltaMessage | None:
"""Parse a single streaming delta, orchestrating reasoning then
tool call extraction via internal stream state.
"""
class DelegatingParser(Parser):
"""
A Parser implementation that delegates to separate ReasoningParser and
ToolParser instances.
This is the recommended base class for creating model-specific parsers
that combine existing reasoning and tool parser implementations.
Subclasses should set `self._reasoning_parser` and `self._tool_parser`
in their `__init__` method.
If either parser is None, the corresponding methods will return default
values (no reasoning extraction, no tool calls).
"""
def extract_reasoning(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
) -> tuple[str | None, str | None]:
if self._reasoning_parser is None:
return None, model_output
return self._reasoning_parser.extract_reasoning(model_output, request)
def _get_function_name(
self, request: ChatCompletionRequest | ResponsesRequest
) -> str:
if request.tool_choice and isinstance(request.tool_choice, ToolChoiceFunction):
return request.tool_choice.name
if request.tool_choice and isinstance(
request.tool_choice, ChatCompletionNamedToolChoiceParam
):
return request.tool_choice.function.name
raise ValueError("Invalid tool_choice for function name extraction.")
def _extract_tool_calls(
self,
content: str | None,
request: ChatCompletionRequest | ResponsesRequest,
enable_auto_tools: bool = False,
) -> tuple[list[FunctionCall] | None, str | None]:
tool_parser = self._tool_parser
if tool_parser is None:
return [], content
supports_required_and_named = tool_parser.supports_required_and_named
is_named_tool_choice = request.tool_choice and isinstance(
request.tool_choice,
(ToolChoiceFunction, ChatCompletionNamedToolChoiceParam),
)
is_required_tool_choice = request.tool_choice == "required"
is_auto_tool_choice = enable_auto_tools and (
request.tool_choice == "auto"
or request.tool_choice is None
or (
not supports_required_and_named
and (is_named_tool_choice or is_required_tool_choice)
)
)
tool_calls = list[FunctionCall]()
if is_named_tool_choice and supports_required_and_named:
if content is None:
return [], None
tool_calls.append(
FunctionCall(
name=self._get_function_name(request),
arguments=content,
)
)
content = None
elif is_required_tool_choice and supports_required_and_named:
# "required" with standard JSON-based parsing
parsed_calls = []
with contextlib.suppress(ValidationError):
content = content or ""
parsed_calls = TypeAdapter(list[FunctionDefinition]).validate_json(
content
)
for tc in parsed_calls:
tool_calls.append(
FunctionCall(
name=tc.name,
arguments=json.dumps(tc.parameters, ensure_ascii=False),
)
)
content = None
elif is_auto_tool_choice:
# Automatic Tool Call Parsing (also used as fallback for
# required/named when supports_required_and_named=False)
tool_call_info = self.extract_tool_calls(
content if content is not None else "",
request=request,
)
if tool_call_info is not None and tool_call_info.tools_called:
tool_calls.extend(
FunctionCall(
id=tc.id,
name=tc.function.name,
arguments=tc.function.arguments,
)
for tc in tool_call_info.tool_calls
)
content = tool_call_info.content
if content and content.strip() == "":
content = None
else:
# No tool calls.
return None, content
return tool_calls, content
def adjust_request(
self, request: ChatCompletionRequest | ResponsesRequest
) -> ChatCompletionRequest | ResponsesRequest:
if self._reasoning_parser is not None:
request = self._reasoning_parser.adjust_request(request)
if self._tool_parser is not None:
request = self._apply_structural_tag(request)
if self._tool_parser is not None:
request = self._tool_parser.adjust_request(request)
return request
def _apply_structural_tag(
self, request: ChatCompletionRequest | ResponsesRequest
) -> ChatCompletionRequest | ResponsesRequest:
if (
not isinstance(request, ChatCompletionRequest)
or self._tool_parser is None
or self._tool_parser.structural_tag_model is None
or not request.tools
):
return request
need_tool_calling = (
request.tool_choice == "auto"
or request.tool_choice == "required"
or isinstance(request.tool_choice, ChatCompletionNamedToolChoiceParam)
)
if not need_tool_calling:
return request
structure_tag = self._tool_parser.get_structural_tag(
request,
reasoning=False,
)
if structure_tag is None:
return request
structural_tag = json.dumps(structure_tag.model_dump())
request.structured_outputs = StructuredOutputsParams(
structural_tag=structural_tag,
)
request.response_format = None
return request
def extract_reasoning_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
) -> DeltaMessage | None:
if self._reasoning_parser is None:
return DeltaMessage(content=delta_text)
return self._reasoning_parser.extract_reasoning_streaming(
previous_text,
current_text,
delta_text,
previous_token_ids,
current_token_ids,
delta_token_ids,
)
def extract_tool_calls(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
) -> ExtractedToolCallInformation:
if self._tool_parser is None:
return ExtractedToolCallInformation(
tools_called=False, tool_calls=[], content=model_output
)
result = None
is_tool_called: bool | Exception = False
try:
result = self._tool_parser.extract_tool_calls(
model_output,
request=request, # type: ignore[arg-type]
)
is_tool_called = bool(result.tools_called)
except Exception as e:
is_tool_called = e
raise
finally:
record_tool_parser_invocation(
is_tool_called=is_tool_called,
is_streaming=False,
request=request,
)
return result
def extract_tool_calls_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
request: ChatCompletionRequest | ResponsesRequest,
) -> DeltaMessage | None:
if self._tool_parser is None:
return None
result = None
is_tool_called: bool | Exception = False
try:
result = self._tool_parser.extract_tool_calls_streaming(
previous_text,
current_text,
delta_text,
previous_token_ids,
current_token_ids,
delta_token_ids,
request, # type: ignore[arg-type]
)
is_tool_called = bool(result and result.tool_calls)
except Exception as e:
is_tool_called = e
raise
finally:
record_tool_parser_invocation(
is_tool_called=is_tool_called,
is_streaming=True,
request=request,
)
return result
def _extract_tool_calls_streaming(
self,
previous_text: str,
current_text: str,
delta_text: str,
previous_token_ids: Sequence[int],
current_token_ids: Sequence[int],
delta_token_ids: Sequence[int],
request: ChatCompletionRequest | ResponsesRequest,
# The following parameters are used for "required" tool choice parsing and are
# tracked in StreamState for streaming parsing.
tool_call_idx: int | None = None,
tool_call_id_type: str = "random",
function_name_returned: bool = False,
) -> tuple[DeltaMessage | None, bool]:
if request.tool_choice == "none":
return (DeltaMessage(content=delta_text) if delta_text else None), False
assert self._tool_parser is not None
supports_required_and_named = self._tool_parser.supports_required_and_named
if (
supports_required_and_named
and request.tool_choice
and isinstance(
request.tool_choice,
(ToolChoiceFunction, ChatCompletionNamedToolChoiceParam),
)
):
delta_message, function_name_returned = extract_named_tool_call_streaming(
delta_text=delta_text,
function_name=self._get_function_name(request),
function_name_returned=function_name_returned,
tool_call_idx=tool_call_idx,
tool_call_id_type=tool_call_id_type,
tokenizer=self.model_tokenizer,
)
return delta_message, function_name_returned
if supports_required_and_named and request.tool_choice == "required":
delta_message, function_name_returned = (
extract_required_tool_call_streaming(
previous_text=previous_text,
current_text=current_text,
delta_text=delta_text,
function_name_returned=function_name_returned,
tool_call_idx=tool_call_idx,
tool_call_id_type=tool_call_id_type,
)
)
return delta_message, function_name_returned
return self.extract_tool_calls_streaming(
previous_text,
current_text,
delta_text,
previous_token_ids,
current_token_ids,
delta_token_ids,
request,
), False
def is_reasoning_end(self, input_ids: list[int]) -> bool:
if self._reasoning_parser is None:
return False
return self._reasoning_parser.is_reasoning_end(input_ids)
def is_reasoning_end_streaming(
self, input_ids: list[int], delta_ids: list[int]
) -> bool:
if self._reasoning_parser is None:
return False
return self._reasoning_parser.is_reasoning_end_streaming(input_ids, delta_ids)
def extract_content_ids(self, input_ids: list[int]) -> list[int]:
if self._reasoning_parser is None:
return input_ids
return self._reasoning_parser.extract_content_ids(input_ids)
def _in_reasoning_phase(self, state: StreamState) -> bool:
if self._reasoning_parser is None:
return False
return not state.reasoning_ended
def _in_tool_call_phase(self, state: StreamState) -> bool:
if self._tool_parser is None:
return False
return state.reasoning_ended
def _append_unstreamed_tool_args(
self,
delta_message: DeltaMessage | None,
) -> None:
"""Append parsed-but-unstreamed tool-call arguments to *delta_message*."""
if (
self._tool_parser is not None
and delta_message
and delta_message.tool_calls
and (last_tc := delta_message.tool_calls[-1]).function
):
last_tc.function.arguments = (
last_tc.function.arguments or ""
) + self._tool_parser.get_remaining_unstreamed_args()
def finalize_generation(
self,
delta_message: DeltaMessage | None,
request: ChatCompletionRequest | ResponsesRequest,
state: StreamState,
) -> DeltaMessage | None:
"""Finalize generation for cases where generation was incomplete.
For example, if streaming terminated before reasoning ended
"""
fallback_fn = getattr(
self._reasoning_parser, "get_streaming_fallback_content", None
)
if fallback_fn is not None and not state.reasoning_ended:
promoted = fallback_fn(state.previous_text, request)
if promoted:
if delta_message is None:
delta_message = DeltaMessage()
delta_message.content = (delta_message.content or "") + promoted
self._append_unstreamed_tool_args(delta_message)
return delta_message
def parse(
self,
model_output: str,
request: ChatCompletionRequest | ResponsesRequest,
enable_auto_tools: bool = False,
model_output_token_ids: Sequence[int] = (),
) -> tuple[str | None, str | None, list[FunctionCall] | None]:
reasoning, content = self.extract_reasoning(model_output, request)
tool_calls, content = self._extract_tool_calls(
content=content,
request=request,
enable_auto_tools=enable_auto_tools,
)
return reasoning, content, tool_calls
def parse_delta(
self,
delta_text: str,
delta_token_ids: list[int],
request: ChatCompletionRequest | ResponsesRequest,
prompt_token_ids: list[int] | None = None,
*,
finished: bool,
) -> DeltaMessage | None:
state = self._stream_state
if not state.prompt_reasoning_checked and prompt_token_ids is not None:
state.prompt_reasoning_checked = True
if self._reasoning_parser is None or self.is_reasoning_end(
prompt_token_ids
):
state.reasoning_ended = True
current_text = state.previous_text + delta_text
current_token_ids = state.previous_token_ids + delta_token_ids
delta_message: DeltaMessage | None = None
# Reasoning extraction
if self._in_reasoning_phase(state):
delta_message = self.extract_reasoning_streaming(
previous_text=state.previous_text,
current_text=current_text,
delta_text=delta_text,
previous_token_ids=state.previous_token_ids,
current_token_ids=current_token_ids,
delta_token_ids=delta_token_ids,
)
if self.is_reasoning_end_streaming(current_token_ids, delta_token_ids):
state.reasoning_ended = True
current_token_ids = self.extract_content_ids(delta_token_ids)
current_text = (
delta_message.content
if delta_message and delta_message.content
else ""
)
delta_text = current_text
delta_token_ids = current_token_ids
# Tool call extraction
if self._in_tool_call_phase(state):
if not state.tool_call_text_started:
state.tool_call_text_started = True
state.previous_text = ""
state.previous_token_ids = []
delta_text = current_text
delta_token_ids = current_token_ids
# A boundary delta may carry both reasoning and tool call,
# save it before the tool parser overwrites delta_message.
reasoning = delta_message.reasoning if delta_message else None
delta_message, state.function_name_returned = (
self._extract_tool_calls_streaming(
previous_text=state.previous_text,
current_text=current_text,
delta_text=delta_text,
previous_token_ids=state.previous_token_ids,
current_token_ids=current_token_ids,
delta_token_ids=delta_token_ids,
request=request, # type: ignore[arg-type]
tool_call_idx=state.history_tool_call_cnt,
tool_call_id_type=state.tool_call_id_type,
function_name_returned=state.function_name_returned,
)
)
if reasoning:
if not delta_message:
delta_message = DeltaMessage()
delta_message.reasoning = reasoning
if (
delta_message
and delta_message.tool_calls
and delta_message.tool_calls[0].id is not None
):
state.history_tool_call_cnt += 1
# No phase active: pass through as content
if (
delta_message is None
and not self._in_reasoning_phase(state)
and not self._in_tool_call_phase(state)
):
delta_message = DeltaMessage(content=delta_text)
state.previous_text = current_text
state.previous_token_ids = current_token_ids
if finished:
delta_message = self.finalize_generation(delta_message, request, state)
return delta_message