distinct method Null safety

Stream<T> distinct(
  1. [bool equals(
    1. T previous,
    2. T next
    )?]
)

Skips data events if they are equal to the previous data event.

The returned stream provides the same events as this stream, except that it never provides two consecutive data events that are equal. That is, errors are passed through to the returned stream, and data events are passed through if they are distinct from the most recently emitted data event.

Equality is determined by the provided equals method. If that is omitted, the '==' operator on the last provided data element is used.

If equals throws, the data event is replaced by an error event containing the thrown error. The behavior is equivalent to the original stream emitting the error event, and it doesn't change the what the most recently emitted data event is.

The returned stream is a broadcast stream if this stream is. If a broadcast stream is listened to more than once, each subscription will individually perform the equals test.

Example:

final stream = Stream.fromIterable([2, 6, 6, 8, 12, 8, 8, 2]).distinct();
stream.forEach(print); // Outputs events: 2,6,8,12,8,2.

Implementation

Stream<T> distinct([bool equals(T previous, T next)?]) {
  return new _DistinctStream<T>(this, equals);
}