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from typing import Any, Dict, List, Union |
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from langchain_core._api import deprecated |
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from langchain_core.messages import BaseMessage, get_buffer_string |
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from langchain.memory.chat_memory import BaseChatMemory |
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@deprecated( |
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since="0.3.1", |
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removal="1.0.0", |
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message=( |
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"Please see the migration guide at: " |
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"https://python.langchain.com/docs/versions/migrating_memory/" |
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), |
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) |
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class ConversationBufferWindowMemory(BaseChatMemory): |
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"""Use to keep track of the last k turns of a conversation. |
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If the number of messages in the conversation is more than the maximum number |
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of messages to keep, the oldest messages are dropped. |
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""" |
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human_prefix: str = "Human" |
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ai_prefix: str = "AI" |
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memory_key: str = "history" |
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k: int = 5 |
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"""Number of messages to store in buffer.""" |
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@property |
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def buffer(self) -> Union[str, List[BaseMessage]]: |
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"""String buffer of memory.""" |
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return self.buffer_as_messages if self.return_messages else self.buffer_as_str |
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@property |
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def buffer_as_str(self) -> str: |
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"""Exposes the buffer as a string in case return_messages is False.""" |
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messages = self.chat_memory.messages[-self.k * 2 :] if self.k > 0 else [] |
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return get_buffer_string( |
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messages, |
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human_prefix=self.human_prefix, |
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ai_prefix=self.ai_prefix, |
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) |
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@property |
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def buffer_as_messages(self) -> List[BaseMessage]: |
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"""Exposes the buffer as a list of messages in case return_messages is True.""" |
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return self.chat_memory.messages[-self.k * 2 :] if self.k > 0 else [] |
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@property |
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def memory_variables(self) -> List[str]: |
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"""Will always return list of memory variables. |
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:meta private: |
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""" |
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return [self.memory_key] |
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def load_memory_variables(self, inputs: Dict[str, Any]) -> Dict[str, Any]: |
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"""Return history buffer.""" |
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return {self.memory_key: self.buffer} |
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