@mjhenkes/postcss-rtl/src/selectors.js

PostCSS plugin for RTL-optimizations

const generatePrefixes = require('./prefixes-config');

const isSelectorHasDir = (selector = '', options) => !!selector.match(generatePrefixes(options)[options.prefixType].regex);

const isHtmlSelector = (selector = '') => !!selector.match(/^html/);

const isRootSelector = (selector = '') => !!selector.match(/:root/);

const addDirToSelectors = (selectors = '', dir, options = {}) => {
  const {addPrefixToSelector, prefixType} = options;
  // we swap direction prefixes if we are converting rtl styles to ltr
  if (options.fromRTL) {
    switch (dir) {
      case 'rtl':
        dir = 'ltr';
        break;
      case 'ltr':
        dir = 'rtl';
        break;
      default:
    }
  }
  const prefix = generatePrefixes(options)[prefixType].prefixes[dir];
  if (!prefix) return selectors;

  return selectors
    .split(/\s*,\s*/)
    .map((selector) => {
      if (addPrefixToSelector) {
        selector = addPrefixToSelector(selector, prefix);
      } else if (isHtmlSelector(selector)) {
        // only replace `html` at the beginning of selector
        selector = selector.replace(/^html/ig, `html${prefix}`);
      } else if (isRootSelector(selector)) {
        selector = selector.replace(/:root/ig, `${prefix}:root`);
      } else {
        // add prefix without html for least change of the priority level
        selector = `${prefix} ${selector}`;
      }
      return selector;
    })
    .join(', ');
};

module.exports = {
  isSelectorHasDir,
  isHtmlSelector,
  isRootSelector,
  addDirToSelectors,
};