%import common.WS
    %ignore WS
"""
[docs]class ISO8601Date(TypedDict):
    """A date in ISO 8601 format (YYYY-MM-DD)."""
    date: str
    type: Literal["date"]
@v_args(inline=True)
class QueryTransformer(Transformer):
    """Transforms a query string into an intermediate representation."""
    def __init__(
        self,
        *args: Any,
        allowed_comparators: Optional[Sequence[Comparator]] = None,
        allowed_operators: Optional[Sequence[Operator]] = None,
        allowed_attributes: Optional[Sequence[str]] = None,
        **kwargs: Any,
    ):
        super().__init__(*args, **kwargs)
        self.allowed_comparators = allowed_comparators
        self.allowed_operators = allowed_operators
        self.allowed_attributes = allowed_attributes
    def program(self, *items: Any) -> tuple:
        return items
    def func_call(self, func_name: Any, args: list) -> FilterDirective:
        func = self._match_func_name(str(func_name))
        if isinstance(func, Comparator):
            if self.allowed_attributes and args[0] not in self.allowed_attributes:
                raise ValueError(
                    f"Received invalid attributes {args[0]}. Allowed attributes are "
                    f"{self.allowed_attributes}"
                )
            return Comparison(comparator=func, attribute=args[0], value=args[1])
        elif len(args) == 1 and func in (Operator.AND, Operator.OR):
            return args[0]
        else:
            return Operation(operator=func, arguments=args)
    def _match_func_name(self, func_name: str) -> Union[Operator, Comparator]:
        if func_name in set(Comparator):


if func_name in set(Comparator):
            if self.allowed_comparators is not None:
                if func_name not in self.allowed_comparators:
                    raise ValueError(
                        f"Received disallowed comparator {func_name}. Allowed "
                        f"comparators are {self.allowed_comparators}"
                    )
            return Comparator(func_name)
        elif func_name in set(Operator):
            if self.allowed_operators is not None:
                if func_name not in self.allowed_operators:
                    raise ValueError(
                        f"Received disallowed operator {func_name}. Allowed operators"
                        f" are {self.allowed_operators}"
                    )
            return Operator(func_name)
        else:
            raise ValueError(
                f"Received unrecognized function {func_name}. Valid functions are "
                f"{list(Operator) + list(Comparator)}"
            )
    def args(self, *items: Any) -> tuple:
        return items
    def false(self) -> bool:
        return False
    def true(self) -> bool:
        return True
    def list(self, item: Any) -> list:
        if item is None:
            return []
        return list(item)
    def int(self, item: Any) -> int:
        return int(item)
    def float(self, item: Any) -> float:
        return float(item)
    def date(self, item: Any) -> ISO8601Date:
        item = str(item).strip("\"'")
        try:
            datetime.datetime.strptime(item, "%Y-%m-%d")
        except ValueError:
            warnings.warn(
                "Dates are expected to be provided in ISO 8601 date format "
                "(YYYY-MM-DD)."
            )


"(YYYY-MM-DD)."
            )
        return {"date": item, "type": "date"}
    def string(self, item: Any) -> str:
        # Remove escaped quotes
        return str(item).strip("\"'")
[docs]def get_parser(
    allowed_comparators: Optional[Sequence[Comparator]] = None,
    allowed_operators: Optional[Sequence[Operator]] = None,
    allowed_attributes: Optional[Sequence[str]] = None,
) -> Lark:
    """
    Returns a parser for the query language.
    Args:
        allowed_comparators: Optional[Sequence[Comparator]]
        allowed_operators: Optional[Sequence[Operator]]
    Returns:
        Lark parser for the query language.
    """
    # QueryTransformer is None when Lark cannot be imported.
    if QueryTransformer is None:
        raise ImportError(
            "Cannot import lark, please install it with 'pip install lark'."
        )
    transformer = QueryTransformer(
        allowed_comparators=allowed_comparators,
        allowed_operators=allowed_operators,
        allowed_attributes=allowed_attributes,
    )
    return Lark(GRAMMAR, parser="lalr", transformer=transformer, start="program")


Source code for langchain.chains.query_constructor.schema
from langchain_core.pydantic_v1 import BaseModel
[docs]class AttributeInfo(BaseModel):
    """Information about a data source attribute."""
    name: str
    description: str
    type: str
    class Config:
        """Configuration for this pydantic object."""
        arbitrary_types_allowed = True
        frozen = True


Source code for langchain.chains.flare.base
from __future__ import annotations
import re
from abc import abstractmethod
from typing import Any, Dict, List, Optional, Sequence, Tuple
import numpy as np
from langchain_core.language_models import BaseLanguageModel
from langchain_core.outputs import Generation
from langchain_core.prompts import BasePromptTemplate
from langchain_core.pydantic_v1 import Field
from langchain_core.retrievers import BaseRetriever
from langchain.callbacks.manager import (
    CallbackManagerForChainRun,
)
from langchain.chains.base import Chain
from langchain.chains.flare.prompts import (
    PROMPT,
    QUESTION_GENERATOR_PROMPT,
    FinishedOutputParser,
)
from langchain.chains.llm import LLMChain
from langchain.llms.openai import OpenAI
class _ResponseChain(LLMChain):
    """Base class for chains that generate responses."""
    prompt: BasePromptTemplate = PROMPT
    @classmethod
    def is_lc_serializable(cls) -> bool:
        return False
    @property
    def input_keys(self) -> List[str]:
        return self.prompt.input_variables
    def generate_tokens_and_log_probs(
        self,
        _input: Dict[str, Any],
        *,
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Tuple[Sequence[str], Sequence[float]]:
        llm_result = self.generate([_input], run_manager=run_manager)
        return self._extract_tokens_and_log_probs(llm_result.generations[0])
    @abstractmethod
    def _extract_tokens_and_log_probs(
        self, generations: List[Generation]
    ) -> Tuple[Sequence[str], Sequence[float]]:
        """Extract tokens and log probs from response."""


"""Extract tokens and log probs from response."""
class _OpenAIResponseChain(_ResponseChain):
    """Chain that generates responses from user input and context."""
    llm: OpenAI = Field(
        default_factory=lambda: OpenAI(
            max_tokens=32, model_kwargs={"logprobs": 1}, temperature=0
        )
    )
    def _extract_tokens_and_log_probs(
        self, generations: List[Generation]
    ) -> Tuple[Sequence[str], Sequence[float]]:
        tokens = []
        log_probs = []
        for gen in generations:
            if gen.generation_info is None:
                raise ValueError
            tokens.extend(gen.generation_info["logprobs"]["tokens"])
            log_probs.extend(gen.generation_info["logprobs"]["token_logprobs"])
        return tokens, log_probs
[docs]class QuestionGeneratorChain(LLMChain):
    """Chain that generates questions from uncertain spans."""
    prompt: BasePromptTemplate = QUESTION_GENERATOR_PROMPT
    """Prompt template for the chain."""
[docs]    @classmethod
    def is_lc_serializable(cls) -> bool:
        return False
    @property
    def input_keys(self) -> List[str]:
        """Input keys for the chain."""
        return ["user_input", "context", "response"]
def _low_confidence_spans(
    tokens: Sequence[str],
    log_probs: Sequence[float],
    min_prob: float,
    min_token_gap: int,
    num_pad_tokens: int,
) -> List[str]:
    _low_idx = np.where(np.exp(log_probs) < min_prob)[0]
    low_idx = [i for i in _low_idx if re.search(r"\w", tokens[i])]
    if len(low_idx) == 0:


if len(low_idx) == 0:
        return []
    spans = [[low_idx[0], low_idx[0] + num_pad_tokens + 1]]
    for i, idx in enumerate(low_idx[1:]):
        end = idx + num_pad_tokens + 1
        if idx - low_idx[i] < min_token_gap:
            spans[-1][1] = end
        else:
            spans.append([idx, end])
    return ["".join(tokens[start:end]) for start, end in spans]
[docs]class FlareChain(Chain):
    """Chain that combines a retriever, a question generator,
    and a response generator."""
    question_generator_chain: QuestionGeneratorChain
    """Chain that generates questions from uncertain spans."""
    response_chain: _ResponseChain = Field(default_factory=_OpenAIResponseChain)
    """Chain that generates responses from user input and context."""
    output_parser: FinishedOutputParser = Field(default_factory=FinishedOutputParser)
    """Parser that determines whether the chain is finished."""
    retriever: BaseRetriever
    """Retriever that retrieves relevant documents from a user input."""
    min_prob: float = 0.2
    """Minimum probability for a token to be considered low confidence."""
    min_token_gap: int = 5
    """Minimum number of tokens between two low confidence spans."""
    num_pad_tokens: int = 2
    """Number of tokens to pad around a low confidence span."""
    max_iter: int = 10
    """Maximum number of iterations."""
    start_with_retrieval: bool = True
    """Whether to start with retrieval."""
    @property
    def input_keys(self) -> List[str]:
        """Input keys for the chain."""
        return ["user_input"]
    @property


"""Input keys for the chain."""
        return ["user_input"]
    @property
    def output_keys(self) -> List[str]:
        """Output keys for the chain."""
        return ["response"]
    def _do_generation(
        self,
        questions: List[str],
        user_input: str,
        response: str,
        _run_manager: CallbackManagerForChainRun,
    ) -> Tuple[str, bool]:
        callbacks = _run_manager.get_child()
        docs = []
        for question in questions:
            docs.extend(self.retriever.get_relevant_documents(question))
        context = "\n\n".join(d.page_content for d in docs)
        result = self.response_chain.predict(
            user_input=user_input,
            context=context,
            response=response,
            callbacks=callbacks,
        )
        marginal, finished = self.output_parser.parse(result)
        return marginal, finished
    def _do_retrieval(
        self,
        low_confidence_spans: List[str],
        _run_manager: CallbackManagerForChainRun,
        user_input: str,
        response: str,
        initial_response: str,
    ) -> Tuple[str, bool]:
        question_gen_inputs = [
            {
                "user_input": user_input,
                "current_response": initial_response,
                "uncertain_span": span,
            }
            for span in low_confidence_spans
        ]
        callbacks = _run_manager.get_child()
        question_gen_outputs = self.question_generator_chain.apply(
            question_gen_inputs, callbacks=callbacks
        )
        questions = [
            output[self.question_generator_chain.output_keys[0]]
            for output in question_gen_outputs
        ]
        _run_manager.on_text(


for output in question_gen_outputs
        ]
        _run_manager.on_text(
            f"Generated Questions: {questions}", color="yellow", end="\n"
        )
        return self._do_generation(questions, user_input, response, _run_manager)
    def _call(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, Any]:
        _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
        user_input = inputs[self.input_keys[0]]
        response = ""
        for i in range(self.max_iter):
            _run_manager.on_text(
                f"Current Response: {response}", color="blue", end="\n"
            )
            _input = {"user_input": user_input, "context": "", "response": response}
            tokens, log_probs = self.response_chain.generate_tokens_and_log_probs(
                _input, run_manager=_run_manager
            )
            low_confidence_spans = _low_confidence_spans(
                tokens,
                log_probs,
                self.min_prob,
                self.min_token_gap,
                self.num_pad_tokens,
            )
            initial_response = response.strip() + " " + "".join(tokens)
            if not low_confidence_spans:
                response = initial_response
                final_response, finished = self.output_parser.parse(response)
                if finished:
                    return {self.output_keys[0]: final_response}
                continue
            marginal, finished = self._do_retrieval(
                low_confidence_spans,
                _run_manager,
                user_input,
                response,
                initial_response,
            )
            response = response.strip() + " " + marginal


initial_response,
            )
            response = response.strip() + " " + marginal
            if finished:
                break
        return {self.output_keys[0]: response}
[docs]    @classmethod
    def from_llm(
        cls, llm: BaseLanguageModel, max_generation_len: int = 32, **kwargs: Any
    ) -> FlareChain:
        """Creates a FlareChain from a language model.
        Args:
            llm: Language model to use.
            max_generation_len: Maximum length of the generated response.
            **kwargs: Additional arguments to pass to the constructor.
        Returns:
            FlareChain class with the given language model.
        """
        question_gen_chain = QuestionGeneratorChain(llm=llm)
        response_llm = OpenAI(
            max_tokens=max_generation_len, model_kwargs={"logprobs": 1}, temperature=0
        )
        response_chain = _OpenAIResponseChain(llm=response_llm)
        return cls(
            question_generator_chain=question_gen_chain,
            response_chain=response_chain,
            **kwargs,
        )


Source code for langchain.chains.flare.prompts
from typing import Tuple
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.prompts import PromptTemplate
[docs]class FinishedOutputParser(BaseOutputParser[Tuple[str, bool]]):
    """Output parser that checks if the output is finished."""
    finished_value: str = "FINISHED"
    """Value that indicates the output is finished."""
[docs]    def parse(self, text: str) -> Tuple[str, bool]:
        cleaned = text.strip()
        finished = self.finished_value in cleaned
        return cleaned.replace(self.finished_value, ""), finished
PROMPT_TEMPLATE = """\
Respond to the user message using any relevant context. \
If context is provided, you should ground your answer in that context. \
Once you're done responding return FINISHED.
>>> CONTEXT: {context}
>>> USER INPUT: {user_input}
>>> RESPONSE: {response}\
"""
PROMPT = PromptTemplate(
    template=PROMPT_TEMPLATE,
    input_variables=["user_input", "context", "response"],
)
QUESTION_GENERATOR_PROMPT_TEMPLATE = """\
Given a user input and an existing partial response as context, \
ask a question to which the answer is the given term/entity/phrase:
>>> USER INPUT: {user_input}
>>> EXISTING PARTIAL RESPONSE: {current_response}
The question to which the answer is the term/entity/phrase "{uncertain_span}" is:"""
QUESTION_GENERATOR_PROMPT = PromptTemplate(
    template=QUESTION_GENERATOR_PROMPT_TEMPLATE,
    input_variables=["user_input", "current_response", "uncertain_span"],
)


Source code for langchain.chains.conversational_retrieval.base
"""Chain for chatting with a vector database."""
from __future__ import annotations
import inspect
import warnings
from abc import abstractmethod
from pathlib import Path
from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
from langchain_core.documents import Document
from langchain_core.language_models import BaseLanguageModel
from langchain_core.messages import BaseMessage
from langchain_core.prompts import BasePromptTemplate
from langchain_core.pydantic_v1 import BaseModel, Extra, Field, root_validator
from langchain_core.retrievers import BaseRetriever
from langchain_core.runnables.config import RunnableConfig
from langchain_core.vectorstores import VectorStore
from langchain.callbacks.manager import (
    AsyncCallbackManagerForChainRun,
    CallbackManagerForChainRun,
    Callbacks,
)
from langchain.chains.base import Chain
from langchain.chains.combine_documents.base import BaseCombineDocumentsChain
from langchain.chains.combine_documents.stuff import StuffDocumentsChain
from langchain.chains.conversational_retrieval.prompts import CONDENSE_QUESTION_PROMPT
from langchain.chains.llm import LLMChain
from langchain.chains.question_answering import load_qa_chain
# Depending on the memory type and configuration, the chat history format may differ.
# This needs to be consolidated.
CHAT_TURN_TYPE = Union[Tuple[str, str], BaseMessage]
_ROLE_MAP = {"human": "Human: ", "ai": "Assistant: "}
def _get_chat_history(chat_history: List[CHAT_TURN_TYPE]) -> str:
    buffer = ""
    for dialogue_turn in chat_history:
        if isinstance(dialogue_turn, BaseMessage):
            role_prefix = _ROLE_MAP.get(dialogue_turn.type, f"{dialogue_turn.type}: ")


buffer += f"\n{role_prefix}{dialogue_turn.content}"
        elif isinstance(dialogue_turn, tuple):
            human = "Human: " + dialogue_turn[0]
            ai = "Assistant: " + dialogue_turn[1]
            buffer += "\n" + "\n".join([human, ai])
        else:
            raise ValueError(
                f"Unsupported chat history format: {type(dialogue_turn)}."
                f" Full chat history: {chat_history} "
            )
    return buffer
[docs]class InputType(BaseModel):
    question: str
    chat_history: List[CHAT_TURN_TYPE] = Field(default_factory=list)
[docs]class BaseConversationalRetrievalChain(Chain):
    """Chain for chatting with an index."""
    combine_docs_chain: BaseCombineDocumentsChain
    """The chain used to combine any retrieved documents."""
    question_generator: LLMChain
    """The chain used to generate a new question for the sake of retrieval.
    This chain will take in the current question (with variable `question`)
    and any chat history (with variable `chat_history`) and will produce
    a new standalone question to be used later on."""
    output_key: str = "answer"
    """The output key to return the final answer of this chain in."""
    rephrase_question: bool = True
    """Whether or not to pass the new generated question to the combine_docs_chain.
    If True, will pass the new generated question along.
    If False, will only use the new generated question for retrieval and pass the
    original question along to the combine_docs_chain."""
    return_source_documents: bool = False
    """Return the retrieved source documents as part of the final result."""
    return_generated_question: bool = False


return_generated_question: bool = False
    """Return the generated question as part of the final result."""
    get_chat_history: Optional[Callable[[List[CHAT_TURN_TYPE]], str]] = None
    """An optional function to get a string of the chat history.
    If None is provided, will use a default."""
    response_if_no_docs_found: Optional[str]
    """If specified, the chain will return a fixed response if no docs
    are found for the question. """
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
        allow_population_by_field_name = True
    @property
    def input_keys(self) -> List[str]:
        """Input keys."""
        return ["question", "chat_history"]
[docs]    def get_input_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        return InputType
    @property
    def output_keys(self) -> List[str]:
        """Return the output keys.
        :meta private:
        """
        _output_keys = [self.output_key]
        if self.return_source_documents:
            _output_keys = _output_keys + ["source_documents"]
        if self.return_generated_question:
            _output_keys = _output_keys + ["generated_question"]
        return _output_keys
    @abstractmethod
    def _get_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: CallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
    def _call(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[CallbackManagerForChainRun] = None,


run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, Any]:
        _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
        question = inputs["question"]
        get_chat_history = self.get_chat_history or _get_chat_history
        chat_history_str = get_chat_history(inputs["chat_history"])
        if chat_history_str:
            callbacks = _run_manager.get_child()
            new_question = self.question_generator.run(
                question=question, chat_history=chat_history_str, callbacks=callbacks
            )
        else:
            new_question = question
        accepts_run_manager = (
            "run_manager" in inspect.signature(self._get_docs).parameters
        )
        if accepts_run_manager:
            docs = self._get_docs(new_question, inputs, run_manager=_run_manager)
        else:
            docs = self._get_docs(new_question, inputs)  # type: ignore[call-arg]
        output: Dict[str, Any] = {}
        if self.response_if_no_docs_found is not None and len(docs) == 0:
            output[self.output_key] = self.response_if_no_docs_found
        else:
            new_inputs = inputs.copy()
            if self.rephrase_question:
                new_inputs["question"] = new_question
            new_inputs["chat_history"] = chat_history_str
            answer = self.combine_docs_chain.run(
                input_documents=docs, callbacks=_run_manager.get_child(), **new_inputs
            )
            output[self.output_key] = answer
        if self.return_source_documents:
            output["source_documents"] = docs
        if self.return_generated_question:
            output["generated_question"] = new_question
        return output
    @abstractmethod
    async def _aget_docs(
        self,


return output
    @abstractmethod
    async def _aget_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: AsyncCallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
    async def _acall(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[AsyncCallbackManagerForChainRun] = None,
    ) -> Dict[str, Any]:
        _run_manager = run_manager or AsyncCallbackManagerForChainRun.get_noop_manager()
        question = inputs["question"]
        get_chat_history = self.get_chat_history or _get_chat_history
        chat_history_str = get_chat_history(inputs["chat_history"])
        if chat_history_str:
            callbacks = _run_manager.get_child()
            new_question = await self.question_generator.arun(
                question=question, chat_history=chat_history_str, callbacks=callbacks
            )
        else:
            new_question = question
        accepts_run_manager = (
            "run_manager" in inspect.signature(self._aget_docs).parameters
        )
        if accepts_run_manager:
            docs = await self._aget_docs(new_question, inputs, run_manager=_run_manager)
        else:
            docs = await self._aget_docs(new_question, inputs)  # type: ignore[call-arg]
        output: Dict[str, Any] = {}
        if self.response_if_no_docs_found is not None and len(docs) == 0:
            output[self.output_key] = self.response_if_no_docs_found
        else:
            new_inputs = inputs.copy()
            if self.rephrase_question:
                new_inputs["question"] = new_question
            new_inputs["chat_history"] = chat_history_str


new_inputs["chat_history"] = chat_history_str
            answer = await self.combine_docs_chain.arun(
                input_documents=docs, callbacks=_run_manager.get_child(), **new_inputs
            )
            output[self.output_key] = answer
        if self.return_source_documents:
            output["source_documents"] = docs
        if self.return_generated_question:
            output["generated_question"] = new_question
        return output
[docs]    def save(self, file_path: Union[Path, str]) -> None:
        if self.get_chat_history:
            raise ValueError("Chain not saveable when `get_chat_history` is not None.")
        super().save(file_path)
[docs]class ConversationalRetrievalChain(BaseConversationalRetrievalChain):
    """Chain for having a conversation based on retrieved documents.
    This chain takes in chat history (a list of messages) and new questions,
    and then returns an answer to that question.
    The algorithm for this chain consists of three parts:
    1. Use the chat history and the new question to create a "standalone question".
    This is done so that this question can be passed into the retrieval step to fetch
    relevant documents. If only the new question was passed in, then relevant context
    may be lacking. If the whole conversation was passed into retrieval, there may
    be unnecessary information there that would distract from retrieval.
    2. This new question is passed to the retriever and relevant documents are
    returned.
    3. The retrieved documents are passed to an LLM along with either the new question
    (default behavior) or the original question and chat history to generate a final
    response.
    Example:
        .. code-block:: python
            from langchain.chains import (


Example:
        .. code-block:: python
            from langchain.chains import (
                StuffDocumentsChain, LLMChain, ConversationalRetrievalChain
            )
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            combine_docs_chain = StuffDocumentsChain(...)
            vectorstore = ...
            retriever = vectorstore.as_retriever()
            # This controls how the standalone question is generated.
            # Should take `chat_history` and `question` as input variables.
            template = (
                "Combine the chat history and follow up question into "
                "a standalone question. Chat History: {chat_history}"
                "Follow up question: {question}"
            )
            prompt = PromptTemplate.from_template(template)
            llm = OpenAI()
            question_generator_chain = LLMChain(llm=llm, prompt=prompt)
            chain = ConversationalRetrievalChain(
                combine_docs_chain=combine_docs_chain,
                retriever=retriever,
                question_generator=question_generator_chain,
            )
    """
    retriever: BaseRetriever
    """Retriever to use to fetch documents."""
    max_tokens_limit: Optional[int] = None
    """If set, enforces that the documents returned are less than this limit.
    This is only enforced if `combine_docs_chain` is of type StuffDocumentsChain."""
    def _reduce_tokens_below_limit(self, docs: List[Document]) -> List[Document]:
        num_docs = len(docs)
        if self.max_tokens_limit and isinstance(
            self.combine_docs_chain, StuffDocumentsChain
        ):
            tokens = [
                self.combine_docs_chain.llm_chain._get_num_tokens(doc.page_content)
                for doc in docs
            ]


for doc in docs
            ]
            token_count = sum(tokens[:num_docs])
            while token_count > self.max_tokens_limit:
                num_docs -= 1
                token_count -= tokens[num_docs]
        return docs[:num_docs]
    def _get_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: CallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
        docs = self.retriever.get_relevant_documents(
            question, callbacks=run_manager.get_child()
        )
        return self._reduce_tokens_below_limit(docs)
    async def _aget_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: AsyncCallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
        docs = await self.retriever.aget_relevant_documents(
            question, callbacks=run_manager.get_child()
        )
        return self._reduce_tokens_below_limit(docs)
[docs]    @classmethod
    def from_llm(
        cls,
        llm: BaseLanguageModel,
        retriever: BaseRetriever,
        condense_question_prompt: BasePromptTemplate = CONDENSE_QUESTION_PROMPT,
        chain_type: str = "stuff",
        verbose: bool = False,
        condense_question_llm: Optional[BaseLanguageModel] = None,
        combine_docs_chain_kwargs: Optional[Dict] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> BaseConversationalRetrievalChain:
        """Convenience method to load chain from LLM and retriever.


"""Convenience method to load chain from LLM and retriever.
        This provides some logic to create the `question_generator` chain
        as well as the combine_docs_chain.
        Args:
            llm: The default language model to use at every part of this chain
                (eg in both the question generation and the answering)
            retriever: The retriever to use to fetch relevant documents from.
            condense_question_prompt: The prompt to use to condense the chat history
                and new question into a standalone question.
            chain_type: The chain type to use to create the combine_docs_chain, will
                be sent to `load_qa_chain`.
            verbose: Verbosity flag for logging to stdout.
            condense_question_llm: The language model to use for condensing the chat
                history and new question into a standalone question. If none is
                provided, will default to `llm`.
            combine_docs_chain_kwargs: Parameters to pass as kwargs to `load_qa_chain`
                when constructing the combine_docs_chain.
            callbacks: Callbacks to pass to all subchains.
            **kwargs: Additional parameters to pass when initializing
                ConversationalRetrievalChain
        """
        combine_docs_chain_kwargs = combine_docs_chain_kwargs or {}
        doc_chain = load_qa_chain(
            llm,
            chain_type=chain_type,
            verbose=verbose,
            callbacks=callbacks,
            **combine_docs_chain_kwargs,
        )
        _llm = condense_question_llm or llm
        condense_question_chain = LLMChain(
            llm=_llm,
            prompt=condense_question_prompt,
            verbose=verbose,
            callbacks=callbacks,
        )
        return cls(
            retriever=retriever,


)
        return cls(
            retriever=retriever,
            combine_docs_chain=doc_chain,
            question_generator=condense_question_chain,
            callbacks=callbacks,
            **kwargs,
        )
[docs]class ChatVectorDBChain(BaseConversationalRetrievalChain):
    """Chain for chatting with a vector database."""
    vectorstore: VectorStore = Field(alias="vectorstore")
    top_k_docs_for_context: int = 4
    search_kwargs: dict = Field(default_factory=dict)
    @property
    def _chain_type(self) -> str:
        return "chat-vector-db"
    @root_validator()
    def raise_deprecation(cls, values: Dict) -> Dict:
        warnings.warn(
            "`ChatVectorDBChain` is deprecated - "
            "please use `from langchain.chains import ConversationalRetrievalChain`"
        )
        return values
    def _get_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: CallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
        vectordbkwargs = inputs.get("vectordbkwargs", {})
        full_kwargs = {**self.search_kwargs, **vectordbkwargs}
        return self.vectorstore.similarity_search(
            question, k=self.top_k_docs_for_context, **full_kwargs
        )
    async def _aget_docs(
        self,
        question: str,
        inputs: Dict[str, Any],
        *,
        run_manager: AsyncCallbackManagerForChainRun,
    ) -> List[Document]:
        """Get docs."""
        raise NotImplementedError("ChatVectorDBChain does not support async")
[docs]    @classmethod


[docs]    @classmethod
    def from_llm(
        cls,
        llm: BaseLanguageModel,
        vectorstore: VectorStore,
        condense_question_prompt: BasePromptTemplate = CONDENSE_QUESTION_PROMPT,
        chain_type: str = "stuff",
        combine_docs_chain_kwargs: Optional[Dict] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> BaseConversationalRetrievalChain:
        """Load chain from LLM."""
        combine_docs_chain_kwargs = combine_docs_chain_kwargs or {}
        doc_chain = load_qa_chain(
            llm,
            chain_type=chain_type,
            callbacks=callbacks,
            **combine_docs_chain_kwargs,
        )
        condense_question_chain = LLMChain(
            llm=llm, prompt=condense_question_prompt, callbacks=callbacks
        )
        return cls(
            vectorstore=vectorstore,
            combine_docs_chain=doc_chain,
            question_generator=condense_question_chain,
            callbacks=callbacks,
            **kwargs,
        )


Source code for langchain.chains.llm_summarization_checker.base
"""Chain for summarization with self-verification."""
from __future__ import annotations
import warnings
from pathlib import Path
from typing import Any, Dict, List, Optional
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.pydantic_v1 import Extra, root_validator
from langchain.callbacks.manager import CallbackManagerForChainRun
from langchain.chains.base import Chain
from langchain.chains.llm import LLMChain
from langchain.chains.sequential import SequentialChain
PROMPTS_DIR = Path(__file__).parent / "prompts"
CREATE_ASSERTIONS_PROMPT = PromptTemplate.from_file(PROMPTS_DIR / "create_facts.txt")
CHECK_ASSERTIONS_PROMPT = PromptTemplate.from_file(PROMPTS_DIR / "check_facts.txt")
REVISED_SUMMARY_PROMPT = PromptTemplate.from_file(PROMPTS_DIR / "revise_summary.txt")
ARE_ALL_TRUE_PROMPT = PromptTemplate.from_file(PROMPTS_DIR / "are_all_true_prompt.txt")
def _load_sequential_chain(
    llm: BaseLanguageModel,
    create_assertions_prompt: PromptTemplate,
    check_assertions_prompt: PromptTemplate,
    revised_summary_prompt: PromptTemplate,
    are_all_true_prompt: PromptTemplate,
    verbose: bool = False,
) -> SequentialChain:
    chain = SequentialChain(
        chains=[
            LLMChain(
                llm=llm,
                prompt=create_assertions_prompt,
                output_key="assertions",
                verbose=verbose,
            ),
            LLMChain(
                llm=llm,
                prompt=check_assertions_prompt,
                output_key="checked_assertions",
                verbose=verbose,
            ),


output_key="checked_assertions",
                verbose=verbose,
            ),
            LLMChain(
                llm=llm,
                prompt=revised_summary_prompt,
                output_key="revised_summary",
                verbose=verbose,
            ),
            LLMChain(
                llm=llm,
                output_key="all_true",
                prompt=are_all_true_prompt,
                verbose=verbose,
            ),
        ],
        input_variables=["summary"],
        output_variables=["all_true", "revised_summary"],
        verbose=verbose,
    )
    return chain
[docs]class LLMSummarizationCheckerChain(Chain):
    """Chain for question-answering with self-verification.
    Example:
        .. code-block:: python
            from langchain.llms import OpenAI
            from langchain.chains import LLMSummarizationCheckerChain
            llm = OpenAI(temperature=0.0)
            checker_chain = LLMSummarizationCheckerChain.from_llm(llm)
    """
    sequential_chain: SequentialChain
    llm: Optional[BaseLanguageModel] = None
    """[Deprecated] LLM wrapper to use."""
    create_assertions_prompt: PromptTemplate = CREATE_ASSERTIONS_PROMPT
    """[Deprecated]"""
    check_assertions_prompt: PromptTemplate = CHECK_ASSERTIONS_PROMPT
    """[Deprecated]"""
    revised_summary_prompt: PromptTemplate = REVISED_SUMMARY_PROMPT
    """[Deprecated]"""
    are_all_true_prompt: PromptTemplate = ARE_ALL_TRUE_PROMPT
    """[Deprecated]"""
    input_key: str = "query"  #: :meta private:
    output_key: str = "result"  #: :meta private:
    max_checks: int = 2


max_checks: int = 2
    """Maximum number of times to check the assertions. Default to double-checking."""
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @root_validator(pre=True)
    def raise_deprecation(cls, values: Dict) -> Dict:
        if "llm" in values:
            warnings.warn(
                "Directly instantiating an LLMSummarizationCheckerChain with an llm is "
                "deprecated. Please instantiate with"
                " sequential_chain argument or using the from_llm class method."
            )
            if "sequential_chain" not in values and values["llm"] is not None:
                values["sequential_chain"] = _load_sequential_chain(
                    values["llm"],
                    values.get("create_assertions_prompt", CREATE_ASSERTIONS_PROMPT),
                    values.get("check_assertions_prompt", CHECK_ASSERTIONS_PROMPT),
                    values.get("revised_summary_prompt", REVISED_SUMMARY_PROMPT),
                    values.get("are_all_true_prompt", ARE_ALL_TRUE_PROMPT),
                    verbose=values.get("verbose", False),
                )
        return values
    @property
    def input_keys(self) -> List[str]:
        """Return the singular input key.
        :meta private:
        """
        return [self.input_key]
    @property
    def output_keys(self) -> List[str]:
        """Return the singular output key.
        :meta private:
        """
        return [self.output_key]
    def _call(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:


) -> Dict[str, str]:
        _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
        all_true = False
        count = 0
        output = None
        original_input = inputs[self.input_key]
        chain_input = original_input
        while not all_true and count < self.max_checks:
            output = self.sequential_chain(
                {"summary": chain_input}, callbacks=_run_manager.get_child()
            )
            count += 1
            if output["all_true"].strip() == "True":
                break
            if self.verbose:
                print(output["revised_summary"])
            chain_input = output["revised_summary"]
        if not output:
            raise ValueError("No output from chain")
        return {self.output_key: output["revised_summary"].strip()}
    @property
    def _chain_type(self) -> str:
        return "llm_summarization_checker_chain"
[docs]    @classmethod
    def from_llm(
        cls,
        llm: BaseLanguageModel,
        create_assertions_prompt: PromptTemplate = CREATE_ASSERTIONS_PROMPT,
        check_assertions_prompt: PromptTemplate = CHECK_ASSERTIONS_PROMPT,
        revised_summary_prompt: PromptTemplate = REVISED_SUMMARY_PROMPT,
        are_all_true_prompt: PromptTemplate = ARE_ALL_TRUE_PROMPT,
        verbose: bool = False,
        **kwargs: Any,
    ) -> LLMSummarizationCheckerChain:
        chain = _load_sequential_chain(
            llm,
            create_assertions_prompt,
            check_assertions_prompt,
            revised_summary_prompt,
            are_all_true_prompt,
            verbose=verbose,
        )
        return cls(sequential_chain=chain, verbose=verbose, **kwargs)


Source code for langchain.chains.combine_documents.reduce
"""Combine many documents together by recursively reducing them."""
from __future__ import annotations
from typing import Any, Callable, List, Optional, Protocol, Tuple
from langchain_core.documents import Document
from langchain_core.pydantic_v1 import Extra
from langchain.callbacks.manager import Callbacks
from langchain.chains.combine_documents.base import BaseCombineDocumentsChain
[docs]class CombineDocsProtocol(Protocol):
    """Interface for the combine_docs method."""
    def __call__(self, docs: List[Document], **kwargs: Any) -> str:
        """Interface for the combine_docs method."""
[docs]class AsyncCombineDocsProtocol(Protocol):
    """Interface for the combine_docs method."""
    async def __call__(self, docs: List[Document], **kwargs: Any) -> str:
        """Async interface for the combine_docs method."""
[docs]def split_list_of_docs(
    docs: List[Document], length_func: Callable, token_max: int, **kwargs: Any
) -> List[List[Document]]:
    """Split Documents into subsets that each meet a cumulative length constraint.
    Args:
        docs: The full list of Documents.
        length_func: Function for computing the cumulative length of a set of Documents.
        token_max: The maximum cumulative length of any subset of Documents.
        **kwargs: Arbitrary additional keyword params to pass to each call of the
            length_func.
    Returns:
        A List[List[Document]].
    """
    new_result_doc_list = []
    _sub_result_docs = []
    for doc in docs:
        _sub_result_docs.append(doc)
        _num_tokens = length_func(_sub_result_docs, **kwargs)
        if _num_tokens > token_max:


if _num_tokens > token_max:
            if len(_sub_result_docs) == 1:
                raise ValueError(
                    "A single document was longer than the context length,"
                    " we cannot handle this."
                )
            new_result_doc_list.append(_sub_result_docs[:-1])
            _sub_result_docs = _sub_result_docs[-1:]
    new_result_doc_list.append(_sub_result_docs)
    return new_result_doc_list
[docs]def collapse_docs(
    docs: List[Document],
    combine_document_func: CombineDocsProtocol,
    **kwargs: Any,
) -> Document:
    """Execute a collapse function on a set of documents and merge their metadatas.
    Args:
        docs: A list of Documents to combine.
        combine_document_func: A function that takes in a list of Documents and
            optionally addition keyword parameters and combines them into a single
            string.
        **kwargs: Arbitrary additional keyword params to pass to the
            combine_document_func.
    Returns:
        A single Document with the output of combine_document_func for the page content
            and the combined metadata's of all the input documents. All metadata values
            are strings, and where there are overlapping keys across documents the
            values are joined by ", ".
    """
    result = combine_document_func(docs, **kwargs)
    combined_metadata = {k: str(v) for k, v in docs[0].metadata.items()}
    for doc in docs[1:]:
        for k, v in doc.metadata.items():
            if k in combined_metadata:
                combined_metadata[k] += f", {v}"
            else:
                combined_metadata[k] = str(v)
    return Document(page_content=result, metadata=combined_metadata)
[docs]async def acollapse_docs(


[docs]async def acollapse_docs(
    docs: List[Document],
    combine_document_func: AsyncCombineDocsProtocol,
    **kwargs: Any,
) -> Document:
    """Execute a collapse function on a set of documents and merge their metadatas.
    Args:
        docs: A list of Documents to combine.
        combine_document_func: A function that takes in a list of Documents and
            optionally addition keyword parameters and combines them into a single
            string.
        **kwargs: Arbitrary additional keyword params to pass to the
            combine_document_func.
    Returns:
        A single Document with the output of combine_document_func for the page content
            and the combined metadata's of all the input documents. All metadata values
            are strings, and where there are overlapping keys across documents the
            values are joined by ", ".
    """
    result = await combine_document_func(docs, **kwargs)
    combined_metadata = {k: str(v) for k, v in docs[0].metadata.items()}
    for doc in docs[1:]:
        for k, v in doc.metadata.items():
            if k in combined_metadata:
                combined_metadata[k] += f", {v}"
            else:
                combined_metadata[k] = str(v)
    return Document(page_content=result, metadata=combined_metadata)
[docs]class ReduceDocumentsChain(BaseCombineDocumentsChain):
    """Combine documents by recursively reducing them.
    This involves
    - combine_documents_chain
    - collapse_documents_chain
    `combine_documents_chain` is ALWAYS provided. This is final chain that is called.
    We pass all previous results to this chain, and the output of this chain is
    returned as a final result.
    `collapse_documents_chain` is used if the documents passed in are too many to all


`collapse_documents_chain` is used if the documents passed in are too many to all
    be passed to `combine_documents_chain` in one go. In this case,
    `collapse_documents_chain` is called recursively on as big of groups of documents
    as are allowed.
    Example:
        .. code-block:: python
            from langchain.chains import (
                StuffDocumentsChain, LLMChain, ReduceDocumentsChain
            )
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            # This controls how each document will be formatted. Specifically,
            # it will be passed to `format_document` - see that function for more
            # details.
            document_prompt = PromptTemplate(
                input_variables=["page_content"],
                 template="{page_content}"
            )
            document_variable_name = "context"
            llm = OpenAI()
            # The prompt here should take as an input variable the
            # `document_variable_name`
            prompt = PromptTemplate.from_template(
                "Summarize this content: {context}"
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)
            combine_documents_chain = StuffDocumentsChain(
                llm_chain=llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name
            )
            chain = ReduceDocumentsChain(
                combine_documents_chain=combine_documents_chain,
            )
            # If we wanted to, we could also pass in collapse_documents_chain
            # which is specifically aimed at collapsing documents BEFORE
            # the final call.
            prompt = PromptTemplate.from_template(
                "Collapse this content: {context}"
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)


llm_chain = LLMChain(llm=llm, prompt=prompt)
            collapse_documents_chain = StuffDocumentsChain(
                llm_chain=llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name
            )
            chain = ReduceDocumentsChain(
                combine_documents_chain=combine_documents_chain,
                collapse_documents_chain=collapse_documents_chain,
            )
    """
    combine_documents_chain: BaseCombineDocumentsChain
    """Final chain to call to combine documents.
    This is typically a StuffDocumentsChain."""
    collapse_documents_chain: Optional[BaseCombineDocumentsChain] = None
    """Chain to use to collapse documents if needed until they can all fit.
    If None, will use the combine_documents_chain.
    This is typically a StuffDocumentsChain."""
    token_max: int = 3000
    """The maximum number of tokens to group documents into. For example, if
    set to 3000 then documents will be grouped into chunks of no greater than
    3000 tokens before trying to combine them into a smaller chunk."""
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @property
    def _collapse_chain(self) -> BaseCombineDocumentsChain:
        if self.collapse_documents_chain is not None:
            return self.collapse_documents_chain
        else:
            return self.combine_documents_chain
[docs]    def combine_docs(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[str, dict]:
        """Combine multiple documents recursively.
        Args:


"""Combine multiple documents recursively.
        Args:
            docs: List of documents to combine, assumed that each one is less than
                `token_max`.
            token_max: Recursively creates groups of documents less than this number
                of tokens.
            callbacks: Callbacks to be passed through
            **kwargs: additional parameters to be passed to LLM calls (like other
                input variables besides the documents)
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        result_docs, extra_return_dict = self._collapse(
            docs, token_max=token_max, callbacks=callbacks, **kwargs
        )
        return self.combine_documents_chain.combine_docs(
            docs=result_docs, callbacks=callbacks, **kwargs
        )
[docs]    async def acombine_docs(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[str, dict]:
        """Async combine multiple documents recursively.
        Args:
            docs: List of documents to combine, assumed that each one is less than
                `token_max`.
            token_max: Recursively creates groups of documents less than this number
                of tokens.
            callbacks: Callbacks to be passed through
            **kwargs: additional parameters to be passed to LLM calls (like other
                input variables besides the documents)
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        result_docs, extra_return_dict = await self._acollapse(
            docs, token_max=token_max, callbacks=callbacks, **kwargs
        )


docs, token_max=token_max, callbacks=callbacks, **kwargs
        )
        return await self.combine_documents_chain.acombine_docs(
            docs=result_docs, callbacks=callbacks, **kwargs
        )
    def _collapse(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[List[Document], dict]:
        result_docs = docs
        length_func = self.combine_documents_chain.prompt_length
        num_tokens = length_func(result_docs, **kwargs)
        def _collapse_docs_func(docs: List[Document], **kwargs: Any) -> str:
            return self._collapse_chain.run(
                input_documents=docs, callbacks=callbacks, **kwargs
            )
        _token_max = token_max or self.token_max
        while num_tokens is not None and num_tokens > _token_max:
            new_result_doc_list = split_list_of_docs(
                result_docs, length_func, _token_max, **kwargs
            )
            result_docs = []
            for docs in new_result_doc_list:
                new_doc = collapse_docs(docs, _collapse_docs_func, **kwargs)
                result_docs.append(new_doc)
            num_tokens = length_func(result_docs, **kwargs)
        return result_docs, {}
    async def _acollapse(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[List[Document], dict]:
        result_docs = docs
        length_func = self.combine_documents_chain.prompt_length
        num_tokens = length_func(result_docs, **kwargs)


num_tokens = length_func(result_docs, **kwargs)
        async def _collapse_docs_func(docs: List[Document], **kwargs: Any) -> str:
            return await self._collapse_chain.arun(
                input_documents=docs, callbacks=callbacks, **kwargs
            )
        _token_max = token_max or self.token_max
        while num_tokens is not None and num_tokens > _token_max:
            new_result_doc_list = split_list_of_docs(
                result_docs, length_func, _token_max, **kwargs
            )
            result_docs = []
            for docs in new_result_doc_list:
                new_doc = await acollapse_docs(docs, _collapse_docs_func, **kwargs)
                result_docs.append(new_doc)
            num_tokens = length_func(result_docs, **kwargs)
        return result_docs, {}
    @property
    def _chain_type(self) -> str:
        return "reduce_documents_chain"


Source code for langchain.chains.combine_documents.base
"""Base interface for chains combining documents."""
from abc import ABC, abstractmethod
from typing import Any, Dict, List, Optional, Tuple, Type
from langchain_core.documents import Document
from langchain_core.pydantic_v1 import BaseModel, Field, create_model
from langchain_core.runnables.config import RunnableConfig
from langchain.callbacks.manager import (
    AsyncCallbackManagerForChainRun,
    CallbackManagerForChainRun,
)
from langchain.chains.base import Chain
from langchain.text_splitter import RecursiveCharacterTextSplitter, TextSplitter
[docs]class BaseCombineDocumentsChain(Chain, ABC):
    """Base interface for chains combining documents.
    Subclasses of this chain deal with combining documents in a variety of
    ways. This base class exists to add some uniformity in the interface these types
    of chains should expose. Namely, they expect an input key related to the documents
    to use (default `input_documents`), and then also expose a method to calculate
    the length of a prompt from documents (useful for outside callers to use to
    determine whether it's safe to pass a list of documents into this chain or whether
    that will longer than the context length).
    """
    input_key: str = "input_documents"  #: :meta private:
    output_key: str = "output_text"  #: :meta private:
[docs]    def get_input_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        return create_model(
            "CombineDocumentsInput",
            **{self.input_key: (List[Document], None)},  # type: ignore[call-overload]
        )
[docs]    def get_output_schema(


)
[docs]    def get_output_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        return create_model(
            "CombineDocumentsOutput",
            **{self.output_key: (str, None)},  # type: ignore[call-overload]
        )
    @property
    def input_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        return [self.input_key]
    @property
    def output_keys(self) -> List[str]:
        """Return output key.
        :meta private:
        """
        return [self.output_key]
[docs]    def prompt_length(self, docs: List[Document], **kwargs: Any) -> Optional[int]:
        """Return the prompt length given the documents passed in.
        This can be used by a caller to determine whether passing in a list
        of documents would exceed a certain prompt length. This useful when
        trying to ensure that the size of a prompt remains below a certain
        context limit.
        Args:
            docs: List[Document], a list of documents to use to calculate the
                total prompt length.
        Returns:
            Returns None if the method does not depend on the prompt length,
            otherwise the length of the prompt in tokens.
        """
        return None
[docs]    @abstractmethod
    def combine_docs(self, docs: List[Document], **kwargs: Any) -> Tuple[str, dict]:
        """Combine documents into a single string.
        Args:
            docs: List[Document], the documents to combine
            **kwargs: Other parameters to use in combining documents, often
                other inputs to the prompt.
        Returns:


other inputs to the prompt.
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
[docs]    @abstractmethod
    async def acombine_docs(
        self, docs: List[Document], **kwargs: Any
    ) -> Tuple[str, dict]:
        """Combine documents into a single string.
        Args:
            docs: List[Document], the documents to combine
            **kwargs: Other parameters to use in combining documents, often
                other inputs to the prompt.
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
    def _call(
        self,
        inputs: Dict[str, List[Document]],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        """Prepare inputs, call combine docs, prepare outputs."""
        _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
        docs = inputs[self.input_key]
        # Other keys are assumed to be needed for LLM prediction
        other_keys = {k: v for k, v in inputs.items() if k != self.input_key}
        output, extra_return_dict = self.combine_docs(
            docs, callbacks=_run_manager.get_child(), **other_keys
        )
        extra_return_dict[self.output_key] = output
        return extra_return_dict
    async def _acall(
        self,
        inputs: Dict[str, List[Document]],
        run_manager: Optional[AsyncCallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        """Prepare inputs, call combine docs, prepare outputs."""


"""Prepare inputs, call combine docs, prepare outputs."""
        _run_manager = run_manager or AsyncCallbackManagerForChainRun.get_noop_manager()
        docs = inputs[self.input_key]
        # Other keys are assumed to be needed for LLM prediction
        other_keys = {k: v for k, v in inputs.items() if k != self.input_key}
        output, extra_return_dict = await self.acombine_docs(
            docs, callbacks=_run_manager.get_child(), **other_keys
        )
        extra_return_dict[self.output_key] = output
        return extra_return_dict
[docs]class AnalyzeDocumentChain(Chain):
    """Chain that splits documents, then analyzes it in pieces.
    This chain is parameterized by a TextSplitter and a CombineDocumentsChain.
    This chain takes a single document as input, and then splits it up into chunks
    and then passes those chucks to the CombineDocumentsChain.
    """
    input_key: str = "input_document"  #: :meta private:
    text_splitter: TextSplitter = Field(default_factory=RecursiveCharacterTextSplitter)
    combine_docs_chain: BaseCombineDocumentsChain
    @property
    def input_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        return [self.input_key]
    @property
    def output_keys(self) -> List[str]:
        """Return output key.
        :meta private:
        """
        return self.combine_docs_chain.output_keys
[docs]    def get_input_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        return create_model(
            "AnalyzeDocumentChain",


return create_model(
            "AnalyzeDocumentChain",
            **{self.input_key: (str, None)},  # type: ignore[call-overload]
        )
[docs]    def get_output_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        return self.combine_docs_chain.get_output_schema(config)
    def _call(
        self,
        inputs: Dict[str, str],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        """Split document into chunks and pass to CombineDocumentsChain."""
        _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
        document = inputs[self.input_key]
        docs = self.text_splitter.create_documents([document])
        # Other keys are assumed to be needed for LLM prediction
        other_keys: Dict = {k: v for k, v in inputs.items() if k != self.input_key}
        other_keys[self.combine_docs_chain.input_key] = docs
        return self.combine_docs_chain(
            other_keys, return_only_outputs=True, callbacks=_run_manager.get_child()
        )


Source code for langchain.chains.combine_documents.map_reduce
"""Combining documents by mapping a chain over them first, then combining results."""
from __future__ import annotations
from typing import Any, Dict, List, Optional, Tuple, Type
from langchain_core.documents import Document
from langchain_core.pydantic_v1 import BaseModel, Extra, create_model, root_validator
from langchain_core.runnables.config import RunnableConfig
from langchain.callbacks.manager import Callbacks
from langchain.chains.combine_documents.base import BaseCombineDocumentsChain
from langchain.chains.combine_documents.reduce import ReduceDocumentsChain
from langchain.chains.llm import LLMChain
[docs]class MapReduceDocumentsChain(BaseCombineDocumentsChain):
    """Combining documents by mapping a chain over them, then combining results.
    We first call `llm_chain` on each document individually, passing in the
    `page_content` and any other kwargs. This is the `map` step.
    We then process the results of that `map` step in a `reduce` step. This should
    likely be a ReduceDocumentsChain.
    Example:
        .. code-block:: python
            from langchain.chains import (
                StuffDocumentsChain,
                LLMChain,
                ReduceDocumentsChain,
                MapReduceDocumentsChain,
            )
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            # This controls how each document will be formatted. Specifically,
            # it will be passed to `format_document` - see that function for more
            # details.
            document_prompt = PromptTemplate(
                input_variables=["page_content"],
                 template="{page_content}"
            )
            document_variable_name = "context"
            llm = OpenAI()
            # The prompt here should take as an input variable the


# The prompt here should take as an input variable the
            # `document_variable_name`
            prompt = PromptTemplate.from_template(
                "Summarize this content: {context}"
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)
            # We now define how to combine these summaries
            reduce_prompt = PromptTemplate.from_template(
                "Combine these summaries: {context}"
            )
            reduce_llm_chain = LLMChain(llm=llm, prompt=reduce_prompt)
            combine_documents_chain = StuffDocumentsChain(
                llm_chain=reduce_llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name
            )
            reduce_documents_chain = ReduceDocumentsChain(
                combine_documents_chain=combine_documents_chain,
            )
            chain = MapReduceDocumentsChain(
                llm_chain=llm_chain,
                reduce_documents_chain=reduce_documents_chain,
            )
            # If we wanted to, we could also pass in collapse_documents_chain
            # which is specifically aimed at collapsing documents BEFORE
            # the final call.
            prompt = PromptTemplate.from_template(
                "Collapse this content: {context}"
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)
            collapse_documents_chain = StuffDocumentsChain(
                llm_chain=llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name
            )
            reduce_documents_chain = ReduceDocumentsChain(
                combine_documents_chain=combine_documents_chain,
                collapse_documents_chain=collapse_documents_chain,
            )
            chain = MapReduceDocumentsChain(
                llm_chain=llm_chain,
                reduce_documents_chain=reduce_documents_chain,
            )
    """


reduce_documents_chain=reduce_documents_chain,
            )
    """
    llm_chain: LLMChain
    """Chain to apply to each document individually."""
    reduce_documents_chain: BaseCombineDocumentsChain
    """Chain to use to reduce the results of applying `llm_chain` to each doc.
    This typically either a ReduceDocumentChain or StuffDocumentChain."""
    document_variable_name: str
    """The variable name in the llm_chain to put the documents in.
    If only one variable in the llm_chain, this need not be provided."""
    return_intermediate_steps: bool = False
    """Return the results of the map steps in the output."""
[docs]    def get_output_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        if self.return_intermediate_steps:
            return create_model(
                "MapReduceDocumentsOutput",
                **{
                    self.output_key: (str, None),
                    "intermediate_steps": (List[str], None),
                },  # type: ignore[call-overload]
            )
        return super().get_output_schema(config)
    @property
    def output_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        _output_keys = super().output_keys
        if self.return_intermediate_steps:
            _output_keys = _output_keys + ["intermediate_steps"]
        return _output_keys
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @root_validator(pre=True)
    def get_reduce_chain(cls, values: Dict) -> Dict:
        """For backwards compatibility."""
        if "combine_document_chain" in values:


"""For backwards compatibility."""
        if "combine_document_chain" in values:
            if "reduce_documents_chain" in values:
                raise ValueError(
                    "Both `reduce_documents_chain` and `combine_document_chain` "
                    "cannot be provided at the same time. `combine_document_chain` "
                    "is deprecated, please only provide `reduce_documents_chain`"
                )
            combine_chain = values["combine_document_chain"]
            collapse_chain = values.get("collapse_document_chain")
            reduce_chain = ReduceDocumentsChain(
                combine_documents_chain=combine_chain,
                collapse_documents_chain=collapse_chain,
            )
            values["reduce_documents_chain"] = reduce_chain
            del values["combine_document_chain"]
            if "collapse_document_chain" in values:
                del values["collapse_document_chain"]
        return values
    @root_validator(pre=True)
    def get_return_intermediate_steps(cls, values: Dict) -> Dict:
        """For backwards compatibility."""
        if "return_map_steps" in values:
            values["return_intermediate_steps"] = values["return_map_steps"]
            del values["return_map_steps"]
        return values
    @root_validator(pre=True)
    def get_default_document_variable_name(cls, values: Dict) -> Dict:
        """Get default document variable name, if not provided."""
        if "document_variable_name" not in values:
            llm_chain_variables = values["llm_chain"].prompt.input_variables
            if len(llm_chain_variables) == 1:
                values["document_variable_name"] = llm_chain_variables[0]
            else:
                raise ValueError(
                    "document_variable_name must be provided if there are "
                    "multiple llm_chain input_variables"
                )
        else:


"multiple llm_chain input_variables"
                )
        else:
            llm_chain_variables = values["llm_chain"].prompt.input_variables
            if values["document_variable_name"] not in llm_chain_variables:
                raise ValueError(
                    f"document_variable_name {values['document_variable_name']} was "
                    f"not found in llm_chain input_variables: {llm_chain_variables}"
                )
        return values
    @property
    def collapse_document_chain(self) -> BaseCombineDocumentsChain:
        """Kept for backward compatibility."""
        if isinstance(self.reduce_documents_chain, ReduceDocumentsChain):
            if self.reduce_documents_chain.collapse_documents_chain:
                return self.reduce_documents_chain.collapse_documents_chain
            else:
                return self.reduce_documents_chain.combine_documents_chain
        else:
            raise ValueError(
                f"`reduce_documents_chain` is of type "
                f"{type(self.reduce_documents_chain)} so it does not have "
                f"this attribute."
            )
    @property
    def combine_document_chain(self) -> BaseCombineDocumentsChain:
        """Kept for backward compatibility."""
        if isinstance(self.reduce_documents_chain, ReduceDocumentsChain):
            return self.reduce_documents_chain.combine_documents_chain
        else:
            raise ValueError(
                f"`reduce_documents_chain` is of type "
                f"{type(self.reduce_documents_chain)} so it does not have "
                f"this attribute."
            )
[docs]    def combine_docs(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[str, dict]:
        """Combine documents in a map reduce manner.


) -> Tuple[str, dict]:
        """Combine documents in a map reduce manner.
        Combine by mapping first chain over all documents, then reducing the results.
        This reducing can be done recursively if needed (if there are many documents).
        """
        map_results = self.llm_chain.apply(
            # FYI - this is parallelized and so it is fast.
            [{self.document_variable_name: d.page_content, **kwargs} for d in docs],
            callbacks=callbacks,
        )
        question_result_key = self.llm_chain.output_key
        result_docs = [
            Document(page_content=r[question_result_key], metadata=docs[i].metadata)
            # This uses metadata from the docs, and the textual results from `results`
            for i, r in enumerate(map_results)
        ]
        result, extra_return_dict = self.reduce_documents_chain.combine_docs(
            result_docs, token_max=token_max, callbacks=callbacks, **kwargs
        )
        if self.return_intermediate_steps:
            intermediate_steps = [r[question_result_key] for r in map_results]
            extra_return_dict["intermediate_steps"] = intermediate_steps
        return result, extra_return_dict
[docs]    async def acombine_docs(
        self,
        docs: List[Document],
        token_max: Optional[int] = None,
        callbacks: Callbacks = None,
        **kwargs: Any,
    ) -> Tuple[str, dict]:
        """Combine documents in a map reduce manner.
        Combine by mapping first chain over all documents, then reducing the results.
        This reducing can be done recursively if needed (if there are many documents).
        """
        map_results = await self.llm_chain.aapply(
            # FYI - this is parallelized and so it is fast.


# FYI - this is parallelized and so it is fast.
            [{**{self.document_variable_name: d.page_content}, **kwargs} for d in docs],
            callbacks=callbacks,
        )
        question_result_key = self.llm_chain.output_key
        result_docs = [
            Document(page_content=r[question_result_key], metadata=docs[i].metadata)
            # This uses metadata from the docs, and the textual results from `results`
            for i, r in enumerate(map_results)
        ]
        result, extra_return_dict = await self.reduce_documents_chain.acombine_docs(
            result_docs, token_max=token_max, callbacks=callbacks, **kwargs
        )
        if self.return_intermediate_steps:
            intermediate_steps = [r[question_result_key] for r in map_results]
            extra_return_dict["intermediate_steps"] = intermediate_steps
        return result, extra_return_dict
    @property
    def _chain_type(self) -> str:
        return "map_reduce_documents_chain"


Source code for langchain.chains.combine_documents.map_rerank
"""Combining documents by mapping a chain over them first, then reranking results."""
from __future__ import annotations
from typing import Any, Dict, List, Optional, Sequence, Tuple, Type, Union, cast
from langchain_core.documents import Document
from langchain_core.pydantic_v1 import BaseModel, Extra, create_model, root_validator
from langchain_core.runnables.config import RunnableConfig
from langchain.callbacks.manager import Callbacks
from langchain.chains.combine_documents.base import BaseCombineDocumentsChain
from langchain.chains.llm import LLMChain
from langchain.output_parsers.regex import RegexParser
[docs]class MapRerankDocumentsChain(BaseCombineDocumentsChain):
    """Combining documents by mapping a chain over them, then reranking results.
    This algorithm calls an LLMChain on each input document. The LLMChain is expected
    to have an OutputParser that parses the result into both an answer (`answer_key`)
    and a score (`rank_key`). The answer with the highest score is then returned.
    Example:
        .. code-block:: python
            from langchain.chains import StuffDocumentsChain, LLMChain
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            from langchain.output_parsers.regex import RegexParser
            document_variable_name = "context"
            llm = OpenAI()
            # The prompt here should take as an input variable the
            # `document_variable_name`
            # The actual prompt will need to be a lot more complex, this is just
            # an example.
            prompt_template = (
                "Use the following context to tell me the chemical formula "
                "for water. Output both your answer and a score of how confident "


"for water. Output both your answer and a score of how confident "
                "you are. Context: {content}"
            )
            output_parser = RegexParser(
                regex=r"(.*?)\nScore: (.*)",
                output_keys=["answer", "score"],
            )
            prompt = PromptTemplate(
                template=prompt_template,
                input_variables=["context"],
                output_parser=output_parser,
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)
            chain = MapRerankDocumentsChain(
                llm_chain=llm_chain,
                document_variable_name=document_variable_name,
                rank_key="score",
                answer_key="answer",
            )
    """
    llm_chain: LLMChain
    """Chain to apply to each document individually."""
    document_variable_name: str
    """The variable name in the llm_chain to put the documents in.
    If only one variable in the llm_chain, this need not be provided."""
    rank_key: str
    """Key in output of llm_chain to rank on."""
    answer_key: str
    """Key in output of llm_chain to return as answer."""
    metadata_keys: Optional[List[str]] = None
    """Additional metadata from the chosen document to return."""
    return_intermediate_steps: bool = False
    """Return intermediate steps.
    Intermediate steps include the results of calling llm_chain on each document."""
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
[docs]    def get_output_schema(
        self, config: Optional[RunnableConfig] = None
    ) -> Type[BaseModel]:
        schema: Dict[str, Any] = {


) -> Type[BaseModel]:
        schema: Dict[str, Any] = {
            self.output_key: (str, None),
        }
        if self.return_intermediate_steps:
            schema["intermediate_steps"] = (List[str], None)
        if self.metadata_keys:
            schema.update({key: (Any, None) for key in self.metadata_keys})
        return create_model("MapRerankOutput", **schema)
    @property
    def output_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        _output_keys = super().output_keys
        if self.return_intermediate_steps:
            _output_keys = _output_keys + ["intermediate_steps"]
        if self.metadata_keys is not None:
            _output_keys += self.metadata_keys
        return _output_keys
    @root_validator()
    def validate_llm_output(cls, values: Dict) -> Dict:
        """Validate that the combine chain outputs a dictionary."""
        output_parser = values["llm_chain"].prompt.output_parser
        if not isinstance(output_parser, RegexParser):
            raise ValueError(
                "Output parser of llm_chain should be a RegexParser,"
                f" got {output_parser}"
            )
        output_keys = output_parser.output_keys
        if values["rank_key"] not in output_keys:
            raise ValueError(
                f"Got {values['rank_key']} as key to rank on, but did not find "
                f"it in the llm_chain output keys ({output_keys})"
            )
        if values["answer_key"] not in output_keys:
            raise ValueError(
                f"Got {values['answer_key']} as key to return, but did not find "


f"it in the llm_chain output keys ({output_keys})"
            )
        return values
    @root_validator(pre=True)
    def get_default_document_variable_name(cls, values: Dict) -> Dict:
        """Get default document variable name, if not provided."""
        if "document_variable_name" not in values:
            llm_chain_variables = values["llm_chain"].prompt.input_variables
            if len(llm_chain_variables) == 1:
                values["document_variable_name"] = llm_chain_variables[0]
            else:
                raise ValueError(
                    "document_variable_name must be provided if there are "
                    "multiple llm_chain input_variables"
                )
        else:
            llm_chain_variables = values["llm_chain"].prompt.input_variables
            if values["document_variable_name"] not in llm_chain_variables:
                raise ValueError(
                    f"document_variable_name {values['document_variable_name']} was "
                    f"not found in llm_chain input_variables: {llm_chain_variables}"
                )
        return values
[docs]    def combine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]:
        """Combine documents in a map rerank manner.
        Combine by mapping first chain over all documents, then reranking the results.
        Args:
            docs: List of documents to combine
            callbacks: Callbacks to be passed through
            **kwargs: additional parameters to be passed to LLM calls (like other
                input variables besides the documents)
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        results = self.llm_chain.apply_and_parse(


"""
        results = self.llm_chain.apply_and_parse(
            # FYI - this is parallelized and so it is fast.
            [{**{self.document_variable_name: d.page_content}, **kwargs} for d in docs],
            callbacks=callbacks,
        )
        return self._process_results(docs, results)
[docs]    async def acombine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]:
        """Combine documents in a map rerank manner.
        Combine by mapping first chain over all documents, then reranking the results.
        Args:
            docs: List of documents to combine
            callbacks: Callbacks to be passed through
            **kwargs: additional parameters to be passed to LLM calls (like other
                input variables besides the documents)
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        results = await self.llm_chain.aapply_and_parse(
            # FYI - this is parallelized and so it is fast.
            [{**{self.document_variable_name: d.page_content}, **kwargs} for d in docs],
            callbacks=callbacks,
        )
        return self._process_results(docs, results)
    def _process_results(
        self,
        docs: List[Document],
        results: Sequence[Union[str, List[str], Dict[str, str]]],
    ) -> Tuple[str, dict]:
        typed_results = cast(List[dict], results)
        sorted_res = sorted(
            zip(typed_results, docs), key=lambda x: -int(x[0][self.rank_key])
        )
        output, document = sorted_res[0]


)
        output, document = sorted_res[0]
        extra_info = {}
        if self.metadata_keys is not None:
            for key in self.metadata_keys:
                extra_info[key] = document.metadata[key]
        if self.return_intermediate_steps:
            extra_info["intermediate_steps"] = results
        return output[self.answer_key], extra_info
    @property
    def _chain_type(self) -> str:
        return "map_rerank_documents_chain"


Source code for langchain.chains.combine_documents.stuff
"""Chain that combines documents by stuffing into context."""
from typing import Any, Dict, List, Optional, Tuple
from langchain_core.documents import Document
from langchain_core.prompts import BasePromptTemplate, format_document
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.pydantic_v1 import Extra, Field, root_validator
from langchain.callbacks.manager import Callbacks
from langchain.chains.combine_documents.base import (
    BaseCombineDocumentsChain,
)
from langchain.chains.llm import LLMChain
def _get_default_document_prompt() -> PromptTemplate:
    return PromptTemplate(input_variables=["page_content"], template="{page_content}")
[docs]class StuffDocumentsChain(BaseCombineDocumentsChain):
    """Chain that combines documents by stuffing into context.
    This chain takes a list of documents and first combines them into a single string.
    It does this by formatting each document into a string with the `document_prompt`
    and then joining them together with `document_separator`. It then adds that new
    string to the inputs with the variable name set by `document_variable_name`.
    Those inputs are then passed to the `llm_chain`.
    Example:
        .. code-block:: python
            from langchain.chains import StuffDocumentsChain, LLMChain
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            # This controls how each document will be formatted. Specifically,
            # it will be passed to `format_document` - see that function for more
            # details.
            document_prompt = PromptTemplate(
                input_variables=["page_content"],
                template="{page_content}"
            )
            document_variable_name = "context"
            llm = OpenAI()


)
            document_variable_name = "context"
            llm = OpenAI()
            # The prompt here should take as an input variable the
            # `document_variable_name`
            prompt = PromptTemplate.from_template(
                "Summarize this content: {context}"
            )
            llm_chain = LLMChain(llm=llm, prompt=prompt)
            chain = StuffDocumentsChain(
                llm_chain=llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name
            )
    """
    llm_chain: LLMChain
    """LLM chain which is called with the formatted document string,
    along with any other inputs."""
    document_prompt: BasePromptTemplate = Field(
        default_factory=_get_default_document_prompt
    )
    """Prompt to use to format each document, gets passed to `format_document`."""
    document_variable_name: str
    """The variable name in the llm_chain to put the documents in.
    If only one variable in the llm_chain, this need not be provided."""
    document_separator: str = "\n\n"
    """The string with which to join the formatted documents"""
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @root_validator(pre=True)
    def get_default_document_variable_name(cls, values: Dict) -> Dict:
        """Get default document variable name, if not provided.
        If only one variable is present in the llm_chain.prompt,
        we can infer that the formatted documents should be passed in
        with this variable name.
        """
        llm_chain_variables = values["llm_chain"].prompt.input_variables
        if "document_variable_name" not in values:


if "document_variable_name" not in values:
            if len(llm_chain_variables) == 1:
                values["document_variable_name"] = llm_chain_variables[0]
            else:
                raise ValueError(
                    "document_variable_name must be provided if there are "
                    "multiple llm_chain_variables"
                )
        else:
            if values["document_variable_name"] not in llm_chain_variables:
                raise ValueError(
                    f"document_variable_name {values['document_variable_name']} was "
                    f"not found in llm_chain input_variables: {llm_chain_variables}"
                )
        return values
    @property
    def input_keys(self) -> List[str]:
        extra_keys = [
            k for k in self.llm_chain.input_keys if k != self.document_variable_name
        ]
        return super().input_keys + extra_keys
    def _get_inputs(self, docs: List[Document], **kwargs: Any) -> dict:
        """Construct inputs from kwargs and docs.
        Format and the join all the documents together into one input with name
        `self.document_variable_name`. The pluck any additional variables
        from **kwargs.
        Args:
            docs: List of documents to format and then join into single input
            **kwargs: additional inputs to chain, will pluck any other required
                arguments from here.
        Returns:
            dictionary of inputs to LLMChain
        """
        # Format each document according to the prompt
        doc_strings = [format_document(doc, self.document_prompt) for doc in docs]
        # Join the documents together to put them in the prompt.
        inputs = {
            k: v
            for k, v in kwargs.items()
            if k in self.llm_chain.prompt.input_variables
        }


if k in self.llm_chain.prompt.input_variables
        }
        inputs[self.document_variable_name] = self.document_separator.join(doc_strings)
        return inputs
[docs]    def prompt_length(self, docs: List[Document], **kwargs: Any) -> Optional[int]:
        """Return the prompt length given the documents passed in.
        This can be used by a caller to determine whether passing in a list
        of documents would exceed a certain prompt length. This useful when
        trying to ensure that the size of a prompt remains below a certain
        context limit.
        Args:
            docs: List[Document], a list of documents to use to calculate the
                total prompt length.
        Returns:
            Returns None if the method does not depend on the prompt length,
            otherwise the length of the prompt in tokens.
        """
        inputs = self._get_inputs(docs, **kwargs)
        prompt = self.llm_chain.prompt.format(**inputs)
        return self.llm_chain._get_num_tokens(prompt)
[docs]    def combine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]:
        """Stuff all documents into one prompt and pass to LLM.
        Args:
            docs: List of documents to join together into one variable
            callbacks: Optional callbacks to pass along
            **kwargs: additional parameters to use to get inputs to LLMChain.
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        inputs = self._get_inputs(docs, **kwargs)
        # Call predict on the LLM.
        return self.llm_chain.predict(callbacks=callbacks, **inputs), {}


return self.llm_chain.predict(callbacks=callbacks, **inputs), {}
[docs]    async def acombine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]:
        """Async stuff all documents into one prompt and pass to LLM.
        Args:
            docs: List of documents to join together into one variable
            callbacks: Optional callbacks to pass along
            **kwargs: additional parameters to use to get inputs to LLMChain.
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        inputs = self._get_inputs(docs, **kwargs)
        # Call predict on the LLM.
        return await self.llm_chain.apredict(callbacks=callbacks, **inputs), {}
    @property
    def _chain_type(self) -> str:
        return "stuff_documents_chain"


Source code for langchain.chains.combine_documents.refine
"""Combine documents by doing a first pass and then refining on more documents."""
from __future__ import annotations
from typing import Any, Dict, List, Tuple
from langchain_core.documents import Document
from langchain_core.prompts import BasePromptTemplate, format_document
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.pydantic_v1 import Extra, Field, root_validator
from langchain.callbacks.manager import Callbacks
from langchain.chains.combine_documents.base import (
    BaseCombineDocumentsChain,
)
from langchain.chains.llm import LLMChain
def _get_default_document_prompt() -> PromptTemplate:
    return PromptTemplate(input_variables=["page_content"], template="{page_content}")
[docs]class RefineDocumentsChain(BaseCombineDocumentsChain):
    """Combine documents by doing a first pass and then refining on more documents.
    This algorithm first calls `initial_llm_chain` on the first document, passing
    that first document in with the variable name `document_variable_name`, and
    produces a new variable with the variable name `initial_response_name`.
    Then, it loops over every remaining document. This is called the "refine" step.
    It calls `refine_llm_chain`,
    passing in that document with the variable name `document_variable_name`
    as well as the previous response with the variable name `initial_response_name`.
    Example:
        .. code-block:: python
            from langchain.chains import RefineDocumentsChain, LLMChain
            from langchain_core.prompts import PromptTemplate
            from langchain.llms import OpenAI
            # This controls how each document will be formatted. Specifically,
            # it will be passed to `format_document` - see that function for more
            # details.


# details.
            document_prompt = PromptTemplate(
                input_variables=["page_content"],
                 template="{page_content}"
            )
            document_variable_name = "context"
            llm = OpenAI()
            # The prompt here should take as an input variable the
            # `document_variable_name`
            prompt = PromptTemplate.from_template(
                "Summarize this content: {context}"
            )
            initial_llm_chain = LLMChain(llm=llm, prompt=prompt)
            initial_response_name = "prev_response"
            # The prompt here should take as an input variable the
            # `document_variable_name` as well as `initial_response_name`
            prompt_refine = PromptTemplate.from_template(
                "Here's your first summary: {prev_response}. "
                "Now add to it based on the following context: {context}"
            )
            refine_llm_chain = LLMChain(llm=llm, prompt=prompt_refine)
            chain = RefineDocumentsChain(
                initial_llm_chain=initial_llm_chain,
                refine_llm_chain=refine_llm_chain,
                document_prompt=document_prompt,
                document_variable_name=document_variable_name,
                initial_response_name=initial_response_name,
            )
    """
    initial_llm_chain: LLMChain
    """LLM chain to use on initial document."""
    refine_llm_chain: LLMChain
    """LLM chain to use when refining."""
    document_variable_name: str
    """The variable name in the initial_llm_chain to put the documents in.
    If only one variable in the initial_llm_chain, this need not be provided."""
    initial_response_name: str
    """The variable name to format the initial response in when refining."""


"""The variable name to format the initial response in when refining."""
    document_prompt: BasePromptTemplate = Field(
        default_factory=_get_default_document_prompt
    )
    """Prompt to use to format each document, gets passed to `format_document`."""
    return_intermediate_steps: bool = False
    """Return the results of the refine steps in the output."""
    @property
    def output_keys(self) -> List[str]:
        """Expect input key.
        :meta private:
        """
        _output_keys = super().output_keys
        if self.return_intermediate_steps:
            _output_keys = _output_keys + ["intermediate_steps"]
        return _output_keys
    class Config:
        """Configuration for this pydantic object."""
        extra = Extra.forbid
        arbitrary_types_allowed = True
    @root_validator(pre=True)
    def get_return_intermediate_steps(cls, values: Dict) -> Dict:
        """For backwards compatibility."""
        if "return_refine_steps" in values:
            values["return_intermediate_steps"] = values["return_refine_steps"]
            del values["return_refine_steps"]
        return values
    @root_validator(pre=True)
    def get_default_document_variable_name(cls, values: Dict) -> Dict:
        """Get default document variable name, if not provided."""
        if "document_variable_name" not in values:
            llm_chain_variables = values["initial_llm_chain"].prompt.input_variables
            if len(llm_chain_variables) == 1:
                values["document_variable_name"] = llm_chain_variables[0]
            else:
                raise ValueError(
                    "document_variable_name must be provided if there are "
                    "multiple llm_chain input_variables"
                )
        else:


"multiple llm_chain input_variables"
                )
        else:
            llm_chain_variables = values["initial_llm_chain"].prompt.input_variables
            if values["document_variable_name"] not in llm_chain_variables:
                raise ValueError(
                    f"document_variable_name {values['document_variable_name']} was "
                    f"not found in llm_chain input_variables: {llm_chain_variables}"
                )
        return values
[docs]    def combine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]:
        """Combine by mapping first chain over all, then stuffing into final chain.
        Args:
            docs: List of documents to combine
            callbacks: Callbacks to be passed through
            **kwargs: additional parameters to be passed to LLM calls (like other
                input variables besides the documents)
        Returns:
            The first element returned is the single string output. The second
            element returned is a dictionary of other keys to return.
        """
        inputs = self._construct_initial_inputs(docs, **kwargs)
        res = self.initial_llm_chain.predict(callbacks=callbacks, **inputs)
        refine_steps = [res]
        for doc in docs[1:]:
            base_inputs = self._construct_refine_inputs(doc, res)
            inputs = {**base_inputs, **kwargs}
            res = self.refine_llm_chain.predict(callbacks=callbacks, **inputs)
            refine_steps.append(res)
        return self._construct_result(refine_steps, res)
[docs]    async def acombine_docs(
        self, docs: List[Document], callbacks: Callbacks = None, **kwargs: Any
    ) -> Tuple[str, dict]: