function getDiacriticsMap() {
    if (diacriticsMap !== null) {
      return diacriticsMap;
    }

    diacriticsMap = {};
    Object.keys(diacritics).forEach(function(key) {
      var characters = diacritics[key];

      for (var index = 0; index < characters.length; index++) {
        var character = characters[index];
        diacriticsMap[character] = key;
      }
    });
    return diacriticsMap;
  }
Creates a map of the diacritics.

@ignore
@returns {Object} Returns the diacritics map.