gray-matter + Assemble to output front matter in pattern library partials

pattern-library-helper.hbs

/**
 * Handlebars Helpers for Pattern Lab
 * Copyright (c) 2014 Jon Schlinkert
 * Licensed under the MIT License (MIT).
 */
'use strict';

var path = require('path');
var file = require('fs-utils');
var _ = require('lodash');
var matter = require('gray-matter');

var inspectProperties = function(obj){
  var str = '';
  for(var k in obj){
    if(obj.hasOwnProperty(k)){
      str += k+ ": " + obj[k] + "\n";
    }
  }
  return str;
}

module.exports.register = function (Handlebars, options, params) {
  options = options || {};

  var config = _.extend(options, options.data || {});

  var patterns = ['atom', 'molecule', 'organism'];

  patterns.forEach(function(pattern) {
    var inflection = pattern + 's';

    file.expand(options.patterns[inflection]).map(function(filepath) {
      var name = pattern + '-' + file.base(filepath);
      var template = file.readFileSync(filepath);
      Handlebars.registerPartial(name, template);
    });

    Handlebars.registerHelper(pattern, function(name, context) {
      context = _.extend(config, context || {});

      var template = Handlebars.partials[pattern + '-' + name];

      var frontMatter = matter(template);

      // the source of the partial without front-matter
      var body = frontMatter.content;

      // the data from lowest-to-highest priority being overridden in front-matter
      var data = _.extend(context, frontMatter.data, this, options.hash);

      var fn = Handlebars.compile(body);
      return new Handlebars.SafeString(fn(data));
    });
  });
};