agsamantha/node_modules/langchain/dist/memory/summary_buffer.js

import { getBufferString } from "@langchain/core/messages";
import { BaseConversationSummaryMemory, } from "./summary.js";
/**
 * Class that extends BaseConversationSummaryMemory and implements
 * ConversationSummaryBufferMemoryInput. It manages the conversation
 * history in a LangChain application by maintaining a buffer of chat
 * messages and providing methods to load, save, prune, and clear the
 * memory.
 * @example
 * ```typescript
 * // Initialize the memory with a specific model and token limit
 * const memory = new ConversationSummaryBufferMemory({
 *   llm: new ChatOpenAI({ modelName: "gpt-3.5-turbo-instruct", temperature: 0 }),
 *   maxTokenLimit: 10,
 * });
 *
 * // Save conversation context to memory
 * await memory.saveContext({ input: "hi" }, { output: "whats up" });
 * await memory.saveContext({ input: "not much you" }, { output: "not much" });
 *
 * // Load the conversation history from memory
 * const history = await memory.loadMemoryVariables({});
 * console.log({ history });
 *
 * // Create a chat prompt using the conversation history
 * const chatPrompt = ChatPromptTemplate.fromMessages([
 *   SystemMessagePromptTemplate.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.",
 *   ),
 *   new MessagesPlaceholder("history"),
 *   HumanMessagePromptTemplate.fromTemplate("{input}"),
 * ]);
 *
 * // Initialize the conversation chain with the model, memory, and prompt
 * const chain = new ConversationChain({
 *   llm: new ChatOpenAI({ temperature: 0.9, verbose: true }),
 *   memory: memory,
 *   prompt: chatPrompt,
 * });
 * ```
 */
export class ConversationSummaryBufferMemory extends BaseConversationSummaryMemory {
    constructor(fields) {
        super(fields);
        Object.defineProperty(this, "movingSummaryBuffer", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: ""
        });
        Object.defineProperty(this, "maxTokenLimit", {
            enumerable: true,
            configurable: true,
            writable: true,
            value: 2000
        });
        this.maxTokenLimit = fields?.maxTokenLimit ?? this.maxTokenLimit;
    }
    get memoryKeys() {
        return [this.memoryKey];
    }
    /**
     * Method that loads the chat messages from the memory and returns them as
     * a string or as a list of messages, depending on the returnMessages
     * property.
     * @param _ InputValues object, not used in this method.
     * @returns Promise that resolves with MemoryVariables object containing the loaded chat messages.
     */
    async loadMemoryVariables(_) {
        let buffer = await this.chatHistory.getMessages();
        if (this.movingSummaryBuffer) {
            buffer = [
                new this.summaryChatMessageClass(this.movingSummaryBuffer),
                ...buffer,
            ];
        }
        let finalBuffer;
        if (this.returnMessages) {
            finalBuffer = buffer;
        }
        else {
            finalBuffer = getBufferString(buffer, this.humanPrefix, this.aiPrefix);
        }
        return { [this.memoryKey]: finalBuffer };
    }
    /**
     * Method that saves the context of the conversation, including the input
     * and output values, and prunes the memory if it exceeds the maximum
     * token limit.
     * @param inputValues InputValues object containing the input values of the conversation.
     * @param outputValues OutputValues object containing the output values of the conversation.
     * @returns Promise that resolves when the context is saved and the memory is pruned.
     */
    async saveContext(inputValues, outputValues) {
        await super.saveContext(inputValues, outputValues);
        await this.prune();
    }
    /**
     * Method that prunes the memory if the total number of tokens in the
     * buffer exceeds the maxTokenLimit. It removes messages from the
     * beginning of the buffer until the total number of tokens is within the
     * limit.
     * @returns Promise that resolves when the memory is pruned.
     */
    async prune() {
        // Prune buffer if it exceeds max token limit
        let buffer = await this.chatHistory.getMessages();
        if (this.movingSummaryBuffer) {
            buffer = [
                new this.summaryChatMessageClass(this.movingSummaryBuffer),
                ...buffer,
            ];
        }
        let currBufferLength = await this.llm.getNumTokens(getBufferString(buffer, this.humanPrefix, this.aiPrefix));
        if (currBufferLength > this.maxTokenLimit) {
            const prunedMemory = [];
            while (currBufferLength > this.maxTokenLimit) {
                const poppedMessage = buffer.shift();
                if (poppedMessage) {
                    prunedMemory.push(poppedMessage);
                    currBufferLength = await this.llm.getNumTokens(getBufferString(buffer, this.humanPrefix, this.aiPrefix));
                }
            }
            this.movingSummaryBuffer = await this.predictNewSummary(prunedMemory, this.movingSummaryBuffer);
        }
    }
    /**
     * Method that clears the memory and resets the movingSummaryBuffer.
     * @returns Promise that resolves when the memory is cleared.
     */
    async clear() {
        await super.clear();
        this.movingSummaryBuffer = "";
    }
}