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#

# Source code for langchain.memory.buffer

    from typing import Any, Dict, List, Optional

    from pydantic import root_validator

    from langchain.memory.chat_memory import BaseChatMemory, BaseMemory
    from langchain.memory.utils import get_prompt_input_key
    from langchain.schema import get_buffer_string

    class ConversationBufferMemory(BaseChatMemory):
        """Buffer for storing conversation memory."""

        human_prefix: str = "Human"
        ai_prefix: str = "AI"
        memory_key: str = "history"  #: :meta private:

        @property
        def buffer(self) -> Any:
            """String buffer of memory."""
            if self.return_messages:
                return self.chat_memory.messages
            else:
                return get_buffer_string(
                    self.chat_memory.messages,
                    human_prefix=self.human_prefix,
                    ai_prefix=self.ai_prefix,
                )

        @property
        def memory_variables(self) -> List[str]:
            """Will always return list of memory variables.

            :meta private:
            """
            return [self.memory_key]

        def load_memory_variables(self, inputs: Dict[str, Any]) -> Dict[str, Any]:
            """Return history buffer."""
            return {self.memory_key: self.buffer}

    class ConversationStringBufferMemory(BaseMemory):
        """Buffer for storing conversation memory."""

        human_prefix: str = "Human"
        ai_prefix: str = "AI"
        """Prefix to use for AI generated responses."""
        buffer: str = ""
        output_key: Optional[str] = None
        input_key: Optional[str] = None
        memory_key: str = "history"  #: :meta private:

        @root_validator()
        def validate_chains(cls, values: Dict) -> Dict:
            """Validate that return messages is not True."""
            if values.get("return_messages", False):
                raise ValueError(
                    "return_messages must be False for ConversationStringBufferMemory"
                )
            return values

        @property
        def memory_variables(self) -> List[str]:
            """Will always return list of memory variables.
            :meta private:
            """
            return [self.memory_key]

        def load_memory_variables(self, inputs: Dict[str, Any]) -> Dict[str, str]:
            """Return history buffer."""
            return {self.memory_key: self.buffer}

        def save_context(self, inputs: Dict[str, Any], outputs: Dict[str, str]) -> None:
            """Save context from this conversation to buffer."""
            if self.input_key is None:
                prompt_input_key = get_prompt_input_key(inputs, self.memory_variables)
            else:
                prompt_input_key = self.input_key
            if self.output_key is None:
                if len(outputs) != 1:
                    raise ValueError(f"One output key expected, got {outputs.keys()}")
                output_key = list(outputs.keys())[0]
            else:
                output_key = self.output_key
            human = f"{self.human_prefix}: " + inputs[prompt_input_key]
            ai = f"{self.ai_prefix}: " + outputs[output_key]
            self.buffer += "\n" + "\n".join([human, ai])

        def clear(self) -> None:
            """Clear memory contents."""
            self.buffer = ""