operator [] method

@override dynamic operator [](Object? key)

The value for the given key, or null if key is not in the map.

Some maps allow null as a value. For those maps, a lookup using this operator cannot distinguish between a key not being in the map, and the key being there with a null value. Methods like containsKey or putIfAbsent can be used if the distinction is important.

Implementation

@override
dynamic operator [](Object? key) {
  final v = _values[key as String];
  if (v?.isNotEmpty != true) return null;
  if (v!.length == 1) {
    return v.first;
  } else {
    return v;
  }
}