@beparallel/langchain-ts/dist/typeGenerator.js

Extracts Langchain prompts and generates TypeScript types.

import fs from 'fs';
import { toPascalCase } from './case.js';
export function generateTypes(prompts, outputPath) {
    const lines = ['// Auto-generated file. Do not edit.', '', ''];
    for (const prompt of prompts) {
        const inputSchema = prompt.inputVariables;
        const promptName = String(prompt.metadata?.lc_hub_repo ?? '');
        const promptDict = prompt.toJSON();
        // @ts-ignore
        const schema = promptDict.kwargs.schema_;
        lines.push('\n');
        lines.push(`/*****************************/`);
        lines.push(`// ${promptName}`);
        lines.push(`/*****************************/`);
        lines.push('\n');
        // Input variables
        lines.push(`export interface ${toPascalCase(promptName)}Variable {`, `  ${inputSchema.map((input) => `${input}: any`).join('\n  ')}`, '}');
        lines.push('\n');
        // Output variables
        lines.push(`export interface ${toPascalCase(promptName)}Output {`, `  ${jsonSchemaToType(schema)}`, '}');
    }
    fs.writeFileSync(outputPath, lines.join('\n'), 'utf-8');
}
function jsonSchemaToType(schema, rootName = 'Root') {
    const parseSchema = (schema, name, increment) => {
        if (schema.type === 'object' && schema.properties) {
            const required = schema.required || [];
            const props = Object.entries(schema.properties)
                .map(([key, value]) => {
                const optional = required.includes(key) ? '' : '?';
                return `${' '.repeat(increment + 1)}${key}${optional}: ${parseSchema(value, key, increment + 1)}`;
            })
                .join('\n');
            return `{\n${' '.repeat(increment)}${props}${' '.repeat(increment)}\n}`;
        }
        else if (schema.type === 'array' && schema.items) {
            return `${parseSchema(schema.items, name, increment + 1)}[]`;
        }
        else if (schema.type === 'string') {
            return 'string';
        }
        else if (schema.type === 'number') {
            return 'number';
        }
        else if (schema.type === 'boolean') {
            return 'boolean';
        }
        else if (schema.type === 'null') {
            return 'null';
        }
        else {
            return 'any';
        }
    };
    if (!schema) {
        return '';
    }
    const typeDef = `${schema.title || rootName}: ${parseSchema(schema, rootName, 1)}`;
    return typeDef;
}