import { BaseTransformOutputParser } from "./transform.js";
import { MessageContentComplex, MessageContentImageUrl, MessageContentText } from "../messages/index.js";
/**
 * OutputParser that parses LLMResult into the top likely string.
 * @example
 * ```typescript
 * const promptTemplate = PromptTemplate.fromTemplate(
 *   "Tell me a joke about {topic}",
 * );
 *
 * const chain = RunnableSequence.from([
 *   promptTemplate,
 *   new ChatOpenAI({}),
 *   new StringOutputParser(),
 * ]);
 *
 * const result = await chain.invoke({ topic: "bears" });
 * console.log("What do you call a bear with no teeth? A gummy bear!");
 * ```
 */
export declare class StringOutputParser extends BaseTransformOutputParser<string> {
    static lc_name(): string;
    lc_namespace: string[];
    lc_serializable: boolean;
    /**
     * Parses a string output from an LLM call. This method is meant to be
     * implemented by subclasses to define how a string output from an LLM
     * should be parsed.
     * @param text The string output from an LLM call.
     * @param callbacks Optional callbacks.
     * @returns A promise of the parsed output.
     */
    parse(text: string): Promise<string>;
    getFormatInstructions(): string;
    protected _textContentToString(content: MessageContentText): string;
    protected _imageUrlContentToString(_content: MessageContentImageUrl): string;
    protected _messageContentComplexToString(content: MessageContentComplex): string;
    protected _baseMessageContentToString(content: MessageContentComplex[]): string;
}