68 lines
2.4 KiB
Python
68 lines
2.4 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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from vllm.entrypoints.openai.protocol import ChatCompletionRequest, ResponsesRequest
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from vllm.reasoning.basic_parsers import BaseThinkingReasoningParser
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class Qwen3ReasoningParser(BaseThinkingReasoningParser):
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"""
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Reasoning parser for the Qwen3 model.
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The Qwen3 model uses <think>...</think> tokens to denote reasoning text
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within its output. The model provides a strict switch to disable reasoning
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output via the 'enable_thinking=False' parameter. This parser extracts the
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reasoning content enclosed by <think> and </think> tokens from the model's
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output.
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"""
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@property
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def start_token(self) -> str:
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"""The token that starts reasoning content."""
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return "<think>"
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@property
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def end_token(self) -> str:
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"""The token that ends reasoning content."""
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return "</think>"
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def extract_reasoning(
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self, model_output: str, request: ChatCompletionRequest | ResponsesRequest
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) -> tuple[str | None, str | None]:
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"""
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Extract reasoning content from the model output.
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Qwen3 has stricter requirements - it needs both start and end tokens
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to be present, unlike other models that work with just the end token.
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For text <think>abc</think>xyz:
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- 'abc' goes to reasoning
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- 'xyz' goes to content
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Returns:
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tuple[Optional[str], Optional[str]]: reasoning content and content
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"""
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# Check if the model output contains both <think> and </think> tokens.
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if self.start_token not in model_output or self.end_token not in model_output:
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return None, model_output
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# Check if the <think> is present in the model output, remove it
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# if it is present.
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model_output_parts = model_output.partition(self.start_token)
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model_output = (
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model_output_parts[2] if model_output_parts[1] else model_output_parts[0]
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)
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# Check if the model output contains the </think> tokens.
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# If the end token is not found, return the model output as is.
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if self.end_token not in model_output:
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return None, model_output
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# Extract reasoning content from the model output.
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reasoning, _, content = model_output.partition(self.end_token)
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final_content = content or None
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return reasoning, final_content
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