function patternRegex() {
  return /\${|( (?=[{,}])|(?=[{,}]) )|{}|{,}|\\,(?=.*[{}])|\/\.(?=.*[{}])|\\\.(?={)|\\{|\\}/;
}
emojify a string (replace :emoji: with an emoji)
@param  {string} str
@param  {function} on_missing (gets emoji name without :: and returns a proper emoji if no emoji was found)
@param  {function} format (wrap the returned emoji in a custom element)
@return {string}