Source code for langchain.memory.buffer_window

from typing import Any, Dict, List, Union

from langchain_core.messages import BaseMessage, get_buffer_string

from langchain.memory.chat_memory import BaseChatMemory

[docs]class ConversationBufferWindowMemory(BaseChatMemory): """Buffer for storing conversation memory inside a limited size window.""" human_prefix: str = "Human" ai_prefix: str = "AI" memory_key: str = "history" #: :meta private: k: int = 5 """Number of messages to store in buffer.""" @property def buffer(self) -> Union[str, List[BaseMessage]]: """String buffer of memory.""" return self.buffer_as_messages if self.return_messages else self.buffer_as_str @property def buffer_as_str(self) -> str: """Exposes the buffer as a string in case return_messages is False.""" messages = self.chat_memory.messages[-self.k * 2 :] if self.k > 0 else [] return get_buffer_string( messages, human_prefix=self.human_prefix, ai_prefix=self.ai_prefix, ) @property def buffer_as_messages(self) -> List[BaseMessage]: """Exposes the buffer as a list of messages in case return_messages is True.""" return self.chat_memory.messages[-self.k * 2 :] if self.k > 0 else [] @property def memory_variables(self) -> List[str]: """Will always return list of memory variables. :meta private: """ return [self.memory_key]
[docs] def load_memory_variables(self, inputs: Dict[str, Any]) -> Dict[str, Any]: """Return history buffer.""" return {self.memory_key: self.buffer}