function parseClassType(componentType) {
  var ret = {
    main: '',
    sub: ''
  };

  if (componentType) {
    var typeArr = componentType.split(TYPE_DELIMITER);
    ret.main = typeArr[0] || '';
    ret.sub = typeArr[1] || '';
  }

  return ret;
}
Notice, parseClassType('') should returns {main: '', sub: ''}
@public