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}