Source code for langchain.chains.router.multi_prompt
"""Use a single chain to route an input to one of multiple llm chains."""
from __future__ import annotations
from typing import Any, Dict, List, Mapping, Optional
from langchain.chains import ConversationChain
from langchain.chains.llm import LLMChain
from langchain.chains.router.base import MultiRouteChain, RouterChain
from langchain.chains.router.llm_router import LLMRouterChain, RouterOutputParser
from langchain.chains.router.multi_prompt_prompt import MULTI_PROMPT_ROUTER_TEMPLATE
from langchain.prompts import PromptTemplate
from langchain.schema.language_model import BaseLanguageModel
[docs]class MultiPromptChain(MultiRouteChain):
    """A multi-route chain that uses an LLM router chain to choose amongst prompts."""
    router_chain: RouterChain
    """Chain for deciding a destination chain and the input to it."""
    destination_chains: Mapping[str, LLMChain]
    """Map of name to candidate chains that inputs can be routed to."""
    default_chain: LLMChain
    """Default chain to use when router doesn't map input to one of the destinations."""
    @property
    def output_keys(self) -> List[str]:
        return ["text"]
[docs]    @classmethod
    def from_prompts(
        cls,
        llm: BaseLanguageModel,
        prompt_infos: List[Dict[str, str]],
        default_chain: Optional[LLMChain] = None,
        **kwargs: Any,
    ) -> MultiPromptChain:
        """Convenience constructor for instantiating from destination prompts."""
        destinations = [f"{p['name']}: {p['description']}" for p in prompt_infos]
        destinations_str = "\n".join(destinations)