@pattern-lab/core/src/lib/markdown_parser.js

Create atomic design systems with Pattern Lab. This is the core API and orchestrator of the ecosystem.

'use strict';
const md = require('markdown-it')();
const yaml = require('js-yaml');
const logger = require('./log');

const markdown_parser = function () {
  /**
   * Converts a markdown block with frontmatter (each is optional, technically) to a well-formed object.
   * @param block - the ".md" file, which can contain frontmatter or not, or only frontmatter.
   * @returns an object with any frontmatter keys, plus a .markdown key
   */
  function parseMarkdownBlock(block) {
    let returnObject = {};

    try {
      // for each block process the yaml frontmatter and markdown
      // even if the pattern only has pattern data without further documentation
      const frontmatterRE = /---\r?\n{1}([\s\S]*)^---([\s\S]*)+/gm;
      const chunks = frontmatterRE.exec(block);

      if (chunks) {
        //we got some frontmatter
        if (chunks && chunks[1]) {
          //parse the yaml if we got it
          const frontmatter = chunks[1];
          returnObject = yaml.load(frontmatter);
        }

        if (chunks[2]) {
          //parse the actual markdown if it exists
          returnObject.markdown = md.render(chunks[2]);
        } else {
          returnObject.markdown = '';
        }
      } else {
        //assume the block was only markdown
        returnObject.markdown = md.render(block);
      }
    } catch (ex) {
      logger.warning(ex);
      logger.warning(`error parsing markdown block ${block}`);
      return undefined;
    }

    //return the frontmatter keys and markdown for a consumer to decide what to do with
    return returnObject;
  }

  return {
    parse: function (block) {
      return parseMarkdownBlock(block);
    },
  };
};

module.exports = markdown_parser;