@parcel/transformer-babel/lib/env.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = getEnvOptions;

var _presetEnv = _interopRequireDefault(require("@babel/preset-env"));

var _getBabelTargets = _interopRequireDefault(require("./getBabelTargets"));

var _utils = require("./utils");

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Generates a @babel/preset-env config for an asset.
 * This is done by finding the source module's target engines, and the app's
 * target engines, and doing a diff to include only the necessary plugins.
 */
async function getEnvOptions(config) {
  // Load the target engines for the app and generate a @babel/preset-env config
  let appBabelTargets = (0, _utils.enginesToBabelTargets)(config.env); // If this is the app module, the source and target will be the same, so just compile everything.
  // Otherwise, load the source engines and generate a babel-present-env config.

  if (!config.isSource) {
    let sourceBabelTargets = await (0, _getBabelTargets.default)(config);

    if (!sourceBabelTargets || !shouldCompileFurther(sourceBabelTargets, appBabelTargets)) {
      return null;
    }
  }

  return {
    targets: appBabelTargets,
    presets: [['@parcel/babel-preset-env', {
      useBuiltIns: 'entry',
      corejs: 3,
      shippedProposals: true,
      ignoreBrowserslistConfig: true,
      targets: appBabelTargets
    }]]
  };
}

function getNeededPlugins(targets) {
  return (0, _presetEnv.default)({
    assertVersion: () => true
  }, {
    targets: targets
  }).plugins.filter(p => p[0]);
}

function shouldCompileFurther(sourceBabelTargets, appBabelTargets) {
  let sourcePlugins = new Set(getNeededPlugins(sourceBabelTargets));
  let appPlugins = getNeededPlugins(appBabelTargets); // If there is any app plugin present that was not used to compile the source,
  // then the asset was built to a higher target and will need to be compiled
  // further

  return appPlugins.some(plugin => {
    return !sourcePlugins.has(plugin);
  });
}