oxc-parser/index.mjs

Oxc Parser Node API

import { createRequire } from 'node:module';
import { parseAsync as parseAsyncBinding, parseSync as parseSyncBinding } from './bindings.mjs';
import { wrap } from './wrap.mjs';

export {
  ExportExportNameKind,
  ExportImportNameKind,
  ExportLocalNameKind,
  ImportNameKind,
  ParseResult,
  Severity,
} from './bindings.mjs';
export { rawTransferSupported } from './raw-transfer/supported.mjs';

const require = createRequire(import.meta.url);

// Lazily loaded as needed
let parseSyncRaw = null,
  parseAsyncRaw,
  parseSyncLazy = null,
  parseAsyncLazy,
  Visitor;

/**
 * Lazy-load code related to raw transfer.
 * @returns {undefined}
 */
function loadRawTransfer() {
  if (parseSyncRaw === null) {
    ({ parseSyncRaw, parseAsyncRaw } = require('./raw-transfer/eager.mjs'));
  }
}

/**
 * Lazy-load code related to raw transfer lazy deserialization.
 * @returns {undefined}
 */
function loadRawTransferLazy() {
  if (parseSyncLazy === null) {
    ({ parseSyncLazy, parseAsyncLazy, Visitor } = require('./raw-transfer/lazy.mjs'));
  }
}

/**
 * Parse JS/TS source synchronously on current thread.
 *
 * @param {string} filename - Filename
 * @param {string} sourceText - Source text of file
 * @param {Object|undefined} options - Parsing options
 * @returns {Object} - Object with property getters for `program`, `module`, `comments`, and `errors`
 * @throws {Error} - If `experimentalRawTransfer` or `experimentalLazy` option is enabled,
 *   and raw transfer is not supported on this platform
 */
export function parseSync(filename, sourceText, options) {
  if (options?.experimentalRawTransfer) {
    loadRawTransfer();
    return parseSyncRaw(filename, sourceText, options);
  }
  if (options?.experimentalLazy) {
    loadRawTransferLazy();
    return parseSyncLazy(filename, sourceText, options);
  }
  return wrap(parseSyncBinding(filename, sourceText, options));
}

/**
 * Parse JS/TS source asynchronously on a separate thread.
 *
 * Note that not all of the workload can happen on a separate thread.
 * Parsing on Rust side does happen in a separate thread, but deserialization of the AST to JS objects
 * has to happen on current thread. This synchronous deserialization work typically outweighs
 * the asynchronous parsing by a factor of between 3 and 20.
 *
 * i.e. the majority of the workload cannot be parallelized by using this method.
 *
 * Generally `parseSync` is preferable to use as it does not have the overhead of spawning a thread.
 * If you need to parallelize parsing multiple files, it is recommended to use worker threads.
 *
 * @param {string} filename - Filename
 * @param {string} sourceText - Source text of file
 * @param {Object|undefined} options - Parsing options
 * @returns {Object} - Object with property getters for `program`, `module`, `comments`, and `errors`
 * @throws {Error} - If `experimentalRawTransfer` or `experimentalLazy` option is enabled,
 *   and raw transfer is not supported on this platform
 */
export async function parseAsync(filename, sourceText, options) {
  if (options?.experimentalRawTransfer) {
    loadRawTransfer();
    return await parseAsyncRaw(filename, sourceText, options);
  }
  if (options?.experimentalLazy) {
    loadRawTransferLazy();
    return await parseAsyncLazy(filename, sourceText, options);
  }
  return wrap(await parseAsyncBinding(filename, sourceText, options));
}

/**
 * Get `Visitor` class to construct visitors with.
 * @returns {function} - `Visitor` class
 */
export function experimentalGetLazyVisitor() {
  loadRawTransferLazy();
  return Visitor;
}