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vllm.reasoning.beam_reasoning_parser

Classes:

BeamReasoningParser

Bases: ResponseTemplateReasoningParser

Selects BeamParser as the reasoning parser.

Source code in vllm/parser/beam.py 
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class BeamReasoningParser(ResponseTemplateReasoningParser):
    """Selects `BeamParser` as the reasoning parser."""

    @classmethod
    def unified_parser_cls(cls) -> type[ResponseTemplateParser]:
        return BeamParser

    @property
    def reasoning_start_str(self) -> str | None:
        if literal := super().reasoning_start_str:
            return literal
        thinking = self.response_template.fields.get(THINKING_FIELD)
        if thinking is None:
            return None
        openers = _openers(thinking, message_start_anchors(self.response_template))
        if not openers:
            return None
        # Budget tracking needs one marker for both a prompt continuation
        # and a complete assistant message in the checkpoint's pattern.
        marker = min(openers, key=len)
        return marker if all(opener.endswith(marker) for opener in openers) else None