class BaseOutputParser(BaseModel, ABC, Generic[T]):
@abstractmethod
def parse(self, text: str) -> T:
"""Parse the output of an LLM call.
A method which takes in a string (assumed output of a language model )
and parses it into some structure.
Args:
text: output of language model
Returns:
structured output
"""
def parse_with_prompt(self, completion: str, prompt: PromptValue) -> Any:
"""Optional method to parse the output of an LLM call with a prompt.
The prompt is largely provided in the event the OutputParser wants
to retry or fix the output in some way, and needs information from
the prompt to do so.
Args:
completion: output of language model
prompt: prompt value
Returns:
structured output
"""
return self.parse(completion)
def get_format_instructions(self) -> str:
"""Instructions on how the LLM output should be formatted."""
raise NotImplementedError
@property
def _type(self) -> str:
"""Return the type key."""
raise NotImplementedError(
f"_type property is not implemented in class {self.__class__.__name__}."
" This is required for serialization."
)
def dict(self, **kwargs: Any) -> Dict:
"""Return dictionary representation of output parser."""
output_parser_dict = super().dict()
output_parser_dict["_type"] = self._type
return output_parser_dict
@property
def _valid_values(self) -> List[str]:
return [e.value for e in self.enum]
def parse(self, response: str) -> Any:
try:
return self.enum(response.strip())
except ValueError:
raise OutputParserException(
f"Response '{response}' is not one of the "
f"expected values: {self._valid_values}"
)
def get_format_instructions(self) -> str:
return f"Select one of the following options: {', '.join(self._valid_values)}"