@radicle/gray-matter/lib/engine.js

Parse front-matter from a string or file. Fast, reliable and easy to use. Parses YAML front matter by default, but also has support for YAML, JSON, TOML or Coffee Front-Matter, with options to set custom delimiters. Used by metalsmith, assemble, verb and

'use strict';

module.exports = function(name, options) {
  let engine = options.engines[name] || options.engines[aliase(name)];
  if (typeof engine === 'undefined') {
    throw new Error('gray-matter engine "' + name + '" is not registered');
  }
  if (typeof engine === 'function') {
    engine = { parse: engine };
  }
  return engine;
};

function aliase(name) {
  switch (name.toLowerCase()) {
    case 'js':
    case 'javascript':
      return 'javascript';
    case 'coffee':
    case 'coffeescript':
    case 'cson':
      return 'coffee';
    case 'yaml':
    case 'yml':
      return 'yaml';
    default: {
      return name;
    }
  }
}