Source code for langchain.agents.react.base

"""Chain that implements the ReAct paper from https://arxiv.org/pdf/2210.03629.pdf."""
from __future__ import annotations

from typing import TYPE_CHECKING, Any, List, Optional, Sequence

from langchain_core._api import deprecated
from langchain_core.documents import Document
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts import BasePromptTemplate
from langchain_core.pydantic_v1 import Field
from langchain_core.tools import BaseTool, Tool

from langchain.agents.agent import Agent, AgentExecutor, AgentOutputParser
from langchain.agents.agent_types import AgentType
from langchain.agents.react.output_parser import ReActOutputParser
from langchain.agents.react.textworld_prompt import TEXTWORLD_PROMPT
from langchain.agents.react.wiki_prompt import WIKI_PROMPT
from langchain.agents.utils import validate_tools_single_input

if TYPE_CHECKING:
    from langchain_community.docstore.base import Docstore


[docs]@deprecated("0.1.0", removal="0.3.0") class ReActDocstoreAgent(Agent): """Agent for the ReAct chain.""" output_parser: AgentOutputParser = Field(default_factory=ReActOutputParser) @classmethod def _get_default_output_parser(cls, **kwargs: Any) -> AgentOutputParser: return ReActOutputParser() @property def _agent_type(self) -> str: """Return Identifier of an agent type.""" return AgentType.REACT_DOCSTORE
[docs] @classmethod def create_prompt(cls, tools: Sequence[BaseTool]) -> BasePromptTemplate: """Return default prompt.""" return WIKI_PROMPT
@classmethod def _validate_tools(cls, tools: Sequence[BaseTool]) -> None: validate_tools_single_input(cls.__name__, tools) super()._validate_tools(tools) if len(tools) != 2: raise ValueError(f"Exactly two tools must be specified, but got {tools}") tool_names = {tool.name for tool in tools} if tool_names != {"Lookup", "Search"}: raise ValueError( f"Tool names should be Lookup and Search, got {tool_names}" ) @property def observation_prefix(self) -> str: """Prefix to append the observation with.""" return "Observation: " @property def _stop(self) -> List[str]: return ["\nObservation:"] @property def llm_prefix(self) -> str: """Prefix to append the LLM call with.""" return "Thought:"
[docs]@deprecated("0.1.0", removal="0.3.0") class DocstoreExplorer: """Class to assist with exploration of a document store."""
[docs] def __init__(self, docstore: Docstore): """Initialize with a docstore, and set initial document to None.""" self.docstore = docstore self.document: Optional[Document] = None self.lookup_str = "" self.lookup_index = 0
[docs] def search(self, term: str) -> str: """Search for a term in the docstore, and if found save.""" result = self.docstore.search(term) if isinstance(result, Document): self.document = result return self._summary else: self.document = None return result
[docs] def lookup(self, term: str) -> str: """Lookup a term in document (if saved).""" if self.document is None: raise ValueError("Cannot lookup without a successful search first") if term.lower() != self.lookup_str: self.lookup_str = term.lower() self.lookup_index = 0 else: self.lookup_index += 1 lookups = [p for p in self._paragraphs if self.lookup_str in p.lower()] if len(lookups) == 0: return "No Results" elif self.lookup_index >= len(lookups): return "No More Results" else: result_prefix = f"(Result {self.lookup_index + 1}/{len(lookups)})" return f"{result_prefix} {lookups[self.lookup_index]}"
@property def _summary(self) -> str: return self._paragraphs[0] @property def _paragraphs(self) -> List[str]: if self.document is None: raise ValueError("Cannot get paragraphs without a document") return self.document.page_content.split("\n\n")
[docs]@deprecated("0.1.0", removal="0.3.0") class ReActTextWorldAgent(ReActDocstoreAgent): """Agent for the ReAct TextWorld chain."""
[docs] @classmethod def create_prompt(cls, tools: Sequence[BaseTool]) -> BasePromptTemplate: """Return default prompt.""" return TEXTWORLD_PROMPT
@classmethod def _validate_tools(cls, tools: Sequence[BaseTool]) -> None: validate_tools_single_input(cls.__name__, tools) super()._validate_tools(tools) if len(tools) != 1: raise ValueError(f"Exactly one tool must be specified, but got {tools}") tool_names = {tool.name for tool in tools} if tool_names != {"Play"}: raise ValueError(f"Tool name should be Play, got {tool_names}")
[docs]@deprecated("0.1.0", removal="0.3.0") class ReActChain(AgentExecutor): """[Deprecated] Chain that implements the ReAct paper.""" def __init__(self, llm: BaseLanguageModel, docstore: Docstore, **kwargs: Any): """Initialize with the LLM and a docstore.""" docstore_explorer = DocstoreExplorer(docstore) tools = [ Tool( name="Search", func=docstore_explorer.search, description="Search for a term in the docstore.", ), Tool( name="Lookup", func=docstore_explorer.lookup, description="Lookup a term in the docstore.", ), ] agent = ReActDocstoreAgent.from_llm_and_tools(llm, tools) super().__init__(agent=agent, tools=tools, **kwargs)