sequential.py — langchain Source File

Source Code

"""Chain pipeline where the outputs of one step feed directly into next."""

from typing import Any

from langchain_core.callbacks import (
    AsyncCallbackManagerForChainRun,
    CallbackManagerForChainRun,
)
from langchain_core.utils.input import get_color_mapping
from pydantic import ConfigDict, model_validator
from typing_extensions import Self

from langchain_classic.chains.base import Chain


class SequentialChain(Chain):
    """Chain where the outputs of one chain feed directly into next."""

    chains: list[Chain]
    input_variables: list[str]
    output_variables: list[str]
    return_all: bool = False

    model_config = ConfigDict(
        arbitrary_types_allowed=True,
        extra="forbid",
    )

    @property
    def input_keys(self) -> list[str]:
        """Return expected input keys to the chain."""
        return self.input_variables

    @property
    def output_keys(self) -> list[str]:
        """Return output key."""
        return self.output_variables

    @model_validator(mode="before")
    @classmethod
    def validate_chains(cls, values: dict) -> Any:
        """Validate that the correct inputs exist for all chains."""
        chains = values["chains"]
        input_variables = values["input_variables"]
        memory_keys = []
        if "memory" in values and values["memory"] is not None:
            """Validate that prompt input variables are consistent."""
            memory_keys = values["memory"].memory_variables
            if set(input_variables).intersection(set(memory_keys)):
                overlapping_keys = set(input_variables) & set(memory_keys)
                msg = (
                    f"The input key(s) {''.join(overlapping_keys)} are found "
                    f"in the Memory keys ({memory_keys}) - please use input and "
                    f"memory keys that don't overlap."
                )
                raise ValueError(msg)

        known_variables = set(input_variables + memory_keys)

        for chain in chains:
// ... (149 more lines)