import { createErr, createOk, Result } from "../option-t/mod.ts"; export interface InvalidURLError { name: "InvalidURLError"; message: string; } export interface NotFoundError { name: "NotFoundError"; message: string; } /** * Extracts the source map URL from the given code. * * This code is based on https://github.com/evanw/source-map-visualization/blob/f3e9dfec20e7bfd9625d03dd0d427affa74a9c43/code.js#L103-L145 under @evanw 's license. * * @param code - The code from which to extract the source map URL. * @param _lang - The language of the code (currently only supports `"js"`). * @returns The extracted source map URL as a `URL` object, or `null` if no source map URL is found. */ export const extractSourceMapURL = ( code: string, base: string | URL | undefined, ): Result<URL, InvalidURLError | NotFoundError> => { let url; // Check for both "//" and "/*" comments. This is mostly done manually // instead of doing it all with a regular expression because Firefox's // regular expression engine crashes with an internal error when the // match is too big. for (const match of code.matchAll(/\/([*/])[#@] *sourceMappingURL=/g)) { const start = match.index + match[0].length; const n = code.length; let end = start; while (end < n && code.charCodeAt(end) > 32) { end++; } if (end === start) continue; if (match[1] === "/" || code.indexOf("*/", end) > 0) { url = code.slice(start, end); break; } } return url ? URL.canParse(url, base) ? createOk(new URL(url, base)) : createErr({ name: "InvalidURLError", message: `Invalid URL: ${url}` }) : notFoundError; }; const notFoundError = createErr<NotFoundError>({ name: "NotFoundError", message: "Source map URL is not found", });