parse_to_ast.js

/* @flow */

const babelParser = require('@babel/parser');

const opts = {
  allowImportExportEverywhere: true,
  sourceType: 'module',
  plugins: [
    'asyncGenerators',
    'exportDefaultFrom',
    'optionalChaining',
    'classConstructorCall',
    'classProperties',
    ['decorators', { decoratorsBeforeExport: false }],
    'doExpressions',
    'exportExtensions',
    'flow',
    'functionBind',
    'functionSent',
    'jsx',
    'objectRestSpread',
    'dynamicImport'
  ]
};

/**
 * Convert flow comment types into flow annotations so that
 * they end up in the final AST. If the source does not contain
 * a flow pragma, the code is returned verbatim.
 * @param {*} source code with flow type comments
 * @returns {string} code with flow annotations
 */
export function commentToFlow(source: string) {
  if (!/@flow/.test(source)) return source;
  return source
    .replace(/\/\*::([^]+?)\*\//g, '$1')
    .replace(/\/\*:\s*([^]+?)\s*\*\//g, ':$1');
}

export function parseToAst(source: string) {
  return babelParser.parse(commentToFlow(source), opts);
}