92 lines
3.7 KiB
JavaScript
92 lines
3.7 KiB
JavaScript
import { getBufferString } from "@langchain/core/messages";
|
|
import { BaseChatMemory } from "./chat_memory.js";
|
|
/**
|
|
* The `BufferMemory` class is a type of memory component used for storing
|
|
* and managing previous chat messages. It is a wrapper around
|
|
* `ChatMessageHistory` that extracts the messages into an input variable.
|
|
* This class is particularly useful in applications like chatbots where
|
|
* it is essential to remember previous interactions. Note: The memory
|
|
* instance represents the history of a single conversation. Therefore, it
|
|
* is not recommended to share the same history or memory instance between
|
|
* two different chains. If you deploy your LangChain app on a serverless
|
|
* environment, do not store memory instances in a variable, as your
|
|
* hosting provider may reset it by the next time the function is called.
|
|
* @example
|
|
* ```typescript
|
|
* // Initialize the memory to store chat history and set up the language model with a specific temperature.
|
|
* const memory = new BufferMemory({ memoryKey: "chat_history" });
|
|
* const model = new ChatOpenAI({ temperature: 0.9 });
|
|
*
|
|
* // Create a prompt template for a friendly conversation between a human and an AI.
|
|
* const prompt =
|
|
* PromptTemplate.fromTemplate(`The following is a friendly conversation between a human and an AI. The AI is talkative and provides lots of specific details from its context. If the AI does not know the answer to a question, it truthfully says it does not know.
|
|
*
|
|
* Current conversation:
|
|
* {chat_history}
|
|
* Human: {input}
|
|
* AI:`);
|
|
*
|
|
* // Set up the chain with the language model, prompt, and memory.
|
|
* const chain = new LLMChain({ llm: model, prompt, memory });
|
|
*
|
|
* // Example usage of the chain to continue the conversation.
|
|
* // The `call` method sends the input to the model and returns the AI's response.
|
|
* const res = await chain.call({ input: "Hi! I'm Jim." });
|
|
* console.log({ res });
|
|
*
|
|
* ```
|
|
*/
|
|
export class BufferMemory extends BaseChatMemory {
|
|
constructor(fields) {
|
|
super({
|
|
chatHistory: fields?.chatHistory,
|
|
returnMessages: fields?.returnMessages ?? false,
|
|
inputKey: fields?.inputKey,
|
|
outputKey: fields?.outputKey,
|
|
});
|
|
Object.defineProperty(this, "humanPrefix", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: "Human"
|
|
});
|
|
Object.defineProperty(this, "aiPrefix", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: "AI"
|
|
});
|
|
Object.defineProperty(this, "memoryKey", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: "history"
|
|
});
|
|
this.humanPrefix = fields?.humanPrefix ?? this.humanPrefix;
|
|
this.aiPrefix = fields?.aiPrefix ?? this.aiPrefix;
|
|
this.memoryKey = fields?.memoryKey ?? this.memoryKey;
|
|
}
|
|
get memoryKeys() {
|
|
return [this.memoryKey];
|
|
}
|
|
/**
|
|
* Loads the memory variables. It takes an `InputValues` object as a
|
|
* parameter and returns a `Promise` that resolves with a
|
|
* `MemoryVariables` object.
|
|
* @param _values `InputValues` object.
|
|
* @returns A `Promise` that resolves with a `MemoryVariables` object.
|
|
*/
|
|
async loadMemoryVariables(_values) {
|
|
const messages = await this.chatHistory.getMessages();
|
|
if (this.returnMessages) {
|
|
const result = {
|
|
[this.memoryKey]: messages,
|
|
};
|
|
return result;
|
|
}
|
|
const result = {
|
|
[this.memoryKey]: getBufferString(messages, this.humanPrefix, this.aiPrefix),
|
|
};
|
|
return result;
|
|
}
|
|
}
|