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langchain/langchain/output_parsers/combining.py

50 lines
1.7 KiB
Python

from __future__ import annotations
from typing import Any, Dict, List
from pydantic import root_validator
from langchain.schema import BaseOutputParser
class CombiningOutputParser(BaseOutputParser):
"""Class to combine multiple output parsers into one."""
parsers: List[BaseOutputParser]
@root_validator()
def validate_parsers(cls, values: Dict[str, Any]) -> Dict[str, Any]:
"""Validate the parsers."""
parsers = values["parsers"]
if len(parsers) < 2:
raise ValueError("Must have at least two parsers")
for parser in parsers:
if parser._type == "combining":
raise ValueError("Cannot nest combining parsers")
if parser._type == "list":
raise ValueError("Cannot comine list parsers")
return values
@property
def _type(self) -> str:
"""Return the type key."""
return "combining"
def get_format_instructions(self) -> str:
"""Instructions on how the LLM output should be formatted."""
initial = f"For your first output: {self.parsers[0].get_format_instructions()}"
subsequent = "\n".join(
f"Complete that output fully. Then produce another output, separated by two newline characters: {p.get_format_instructions()}" # noqa: E501
for p in self.parsers[1:]
)
return f"{initial}\n{subsequent}"
def parse(self, text: str) -> Dict[str, Any]:
"""Parse the output of an LLM call."""
texts = text.split("\n\n")
output = dict()
for txt, parser in zip(texts, self.parsers):
output.update(parser.parse(txt.strip()))
return output