117 lines
3.4 KiB
Python
117 lines
3.4 KiB
Python
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from __future__ import annotations
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from typing import Any
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from langchain_core.output_parsers import BaseOutputParser
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from langchain_core.output_parsers.json import parse_and_check_json_markdown
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from pydantic import BaseModel
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from typing_extensions import override
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from langchain_classic.output_parsers.format_instructions import (
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STRUCTURED_FORMAT_INSTRUCTIONS,
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STRUCTURED_FORMAT_SIMPLE_INSTRUCTIONS,
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)
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line_template = '\t"{name}": {type} // {description}'
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class ResponseSchema(BaseModel):
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"""Schema for a response from a structured output parser."""
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name: str
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"""The name of the schema."""
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description: str
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"""The description of the schema."""
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type: str = "string"
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"""The type of the response."""
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def _get_sub_string(schema: ResponseSchema) -> str:
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return line_template.format(
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name=schema.name,
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description=schema.description,
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type=schema.type,
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)
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class StructuredOutputParser(BaseOutputParser[dict[str, Any]]):
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"""Parse the output of an LLM call to a structured output."""
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response_schemas: list[ResponseSchema]
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"""The schemas for the response."""
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@classmethod
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def from_response_schemas(
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cls,
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response_schemas: list[ResponseSchema],
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) -> StructuredOutputParser:
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"""Create a StructuredOutputParser from a list of ResponseSchema.
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Args:
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response_schemas: The schemas for the response.
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Returns:
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An instance of StructuredOutputParser.
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"""
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return cls(response_schemas=response_schemas)
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def get_format_instructions(
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self,
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only_json: bool = False, # noqa: FBT001,FBT002
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) -> str:
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"""Get format instructions for the output parser.
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Example:
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```python
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from langchain_classic.output_parsers.structured import (
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StructuredOutputParser, ResponseSchema
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)
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response_schemas = [
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ResponseSchema(
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name="foo",
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description="a list of strings",
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type="List[string]"
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),
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ResponseSchema(
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name="bar",
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description="a string",
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type="string"
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),
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]
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parser = StructuredOutputParser.from_response_schemas(response_schemas)
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print(parser.get_format_instructions()) # noqa: T201
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output:
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# The output should be a Markdown code snippet formatted in the following
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# schema, including the leading and trailing "```json" and "```":
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#
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# ```json
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# {
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# "foo": List[string] // a list of strings
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# "bar": string // a string
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# }
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# ```
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Args:
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only_json: If `True`, only the json in the Markdown code snippet
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will be returned, without the introducing text.
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"""
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schema_str = "\n".join(
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[_get_sub_string(schema) for schema in self.response_schemas],
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)
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if only_json:
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return STRUCTURED_FORMAT_SIMPLE_INSTRUCTIONS.format(format=schema_str)
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return STRUCTURED_FORMAT_INSTRUCTIONS.format(format=schema_str)
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@override
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def parse(self, text: str) -> dict[str, Any]:
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expected_keys = [rs.name for rs in self.response_schemas]
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return parse_and_check_json_markdown(text, expected_keys)
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@property
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def _type(self) -> str:
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return "structured"
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