@instructure/ui-themeable/es/parseCss.js

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 - present Instructure, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * ---
 * category: utilities/themes
 * ---
 * Parses a CSS string into an AST object
 * @module parseCss
 * @param {String} cssText CSS string to parse
 * @returns {Object} AST for the CSS string
 */
function parseCss() {
  var cssText = arguments.length > 0 && arguments[0] !== void 0 ? arguments[0] : '';
  var cleaned = cleanCss(cssText);
  return parseLexed(lex(cleaned), cleaned);
}
/**
 * CSSRule types (https://developer.mozilla.org/en-US/docs/Web/API/CSSRule)
 */


var ruleTypes = {
  style: 1,
  keyframes: 7,
  media: 4
};
/**
 * Removes comments and import statements from a CSS string
 * (to prep for parsing and applying transforms)
 * @param {String} cssText CSS string to parse
 * @returns {String} cleaned CSS string
 */

function cleanCss() {
  var text = arguments.length > 0 && arguments[0] !== void 0 ? arguments[0] : '';
  // remove comments and imports
  return text.replace(/\/\*[^*]*\*+([^/*][^*]*\*+)*\//gim, '').replace(/@import[^;]*;/gim, '');
}

function lex(text) {
  var rootNode = {
    start: 0,
    end: text.length
  };
  var node = rootNode;
  var chars = text.split('');
  chars.forEach(function (char, i) {
    switch (char) {
      case '{':
        {
          if (!node.rules) {
            node.rules = [];
          }

          var parent = node;
          var previous = parent.rules[parent.rules.length - 1];
          node = {
            start: i + 1,
            parent: parent,
            previous: previous
          };
          parent.rules.push(node);
          break;
        }

      case '}':
        {
          node.end = i + 1;
          node = node.parent || rootNode;
          break;
        }

      default:
        {
          break;
        }
    }
  });
  return rootNode;
}

function parseSelector(node, text) {
  var start = node.previous ? node.previous.end : node.parent.start;
  var end = node.start - 1;
  var selector = text.substring(start, end);
  selector = selector.replace(/\s+/g, ' ');
  selector = selector.substring(selector.lastIndexOf(';') + 1);
  return selector.trim();
}

function parseRuleType(selector) {
  if (selector.indexOf('@') === 0) {
    if (selector.indexOf('@media') === 0) {
      return ruleTypes.media;
    } else if (selector.match(/^@[^\s]*keyframes/)) {
      return ruleTypes.keyframes;
    }
  } else {
    return ruleTypes.style;
  }
}

function parseLexed(node) {
  var text = arguments.length > 1 && arguments[1] !== void 0 ? arguments[1] : '';

  /* eslint-disable no-param-reassign */
  if (node.parent) {
    node.selector = parseSelector(node, text);
    node.type = parseRuleType(node.selector);
  }

  node.cssText = text.substring(node.start, node.end - 1).trim();

  if (node.rules && node.rules.length > 0) {
    node.rules = node.rules.map(function (rule) {
      return parseLexed(rule, text);
    });
  }
  /* eslint-enable no-param-reassign */


  return node;
}

export default parseCss;
export { parseCss, cleanCss, ruleTypes };