react/scripts/flow/createFlowConfigs.js

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow
 */

'use strict';

const chalk = require('chalk');
const fs = require('fs');
const mkdirp = require('mkdirp');
const inlinedHostConfigs = require('../shared/inlinedHostConfigs');

const configTemplate = fs
  .readFileSync(__dirname + '/config/flowconfig')
  .toString();

function writeConfig(renderer) {
  const folder = __dirname + '/' + renderer;
  mkdirp.sync(folder);

  const config = configTemplate.replace(
    '%REACT_RENDERER_FLOW_OPTIONS%',
    `
module.name_mapper='react-reconciler/inline.${renderer}$$' -> 'react-reconciler/inline-typed'
module.name_mapper='ReactFiberHostConfig$$' -> 'forks/ReactFiberHostConfig.${renderer}'
    `.trim(),
  );

  const disclaimer = `
# ---------------------------------------------------------------#
# NOTE: this file is generated.                                  #
# If you want to edit it, open ./scripts/flow/config/flowconfig. #
# Then run Yarn for changes to take effect.                      #
# ---------------------------------------------------------------#
  `.trim();

  const configFile = folder + '/.flowconfig';
  let oldConfig;
  try {
    oldConfig = fs.readFileSync(configFile).toString();
  } catch (err) {
    oldConfig = null;
  }
  const newConfig = `
${disclaimer}
${config}
${disclaimer}
`.trim();

  if (newConfig !== oldConfig) {
    fs.writeFileSync(configFile, newConfig);
    console.log(chalk.dim('Wrote a Flow config to ' + configFile));
  }
}

// Write multiple configs in different folders
// so that we can run those checks in parallel if we want.
inlinedHostConfigs.forEach(rendererInfo => {
  if (rendererInfo.isFlowTyped) {
    writeConfig(rendererInfo.shortName);
  }
});