| [](https://travis-ci.org/dart-lang/stream_transform) |
| [](https://pub.dev/packages/stream_transform) |
| |
| Extension methods on `Stream` adding common transform operators. |
| |
| # Operators |
| |
| ## asyncMapBuffer, asyncMapSample, concurrentAsyncMap |
| |
| Alternatives to `asyncMap`. `asyncMapBuffer` prevents the callback from |
| overlapping execution and collects events while it is executing. |
| `asyncMapSample` prevents overlapping execution and discards events while it is |
| executing. `concurrentAsyncMap` allows overlap and removes ordering guarantees |
| for higher throughput. |
| |
| Like `asyncMap` but events are buffered in a List until previous events have |
| been processed rather than being called for each element individually. |
| |
| ## asyncWhere |
| |
| Like `where` but allows an asynchronous predicate. |
| |
| ## audit |
| |
| Waits for a period of time after receiving a value and then only emits the most |
| recent value. |
| |
| ## buffer |
| |
| Collects values from a source stream until a `trigger` stream fires and the |
| collected values are emitted. |
| |
| ## combineLatest, combineLatestAll |
| |
| Combine the most recent event from multiple streams through a callback or into a |
| list. |
| |
| ## debounce, debounceBuffer |
| |
| Prevents a source stream from emitting too frequently by dropping or collecting |
| values that occur within a given duration. |
| |
| ## followedBy |
| |
| Appends the values of a stream after another stream finishes. |
| |
| ## merge, mergeAll, concurrentAsyncExpand |
| |
| Interleaves events from multiple streams into a single stream. |
| |
| ## scan |
| |
| Scan is like fold, but instead of producing a single value it yields each |
| intermediate accumulation. |
| |
| ## startWith, startWithMany, startWithStream |
| |
| Prepend a value, an iterable, or a stream to the beginning of another stream. |
| |
| ## switchMap, switchLatest |
| |
| Flatten a Stream of Streams into a Stream which forwards values from the most |
| recent Stream |
| |
| ## takeUntil |
| |
| Let values through until a Future fires. |
| |
| ## tap |
| |
| Taps into a single-subscriber stream to react to values as they pass, without |
| being a real subscriber. |
| |
| ## throttle |
| |
| Blocks events for a duration after an event is successfully emitted. |
| |
| ## whereType |
| |
| Like `Iterable.whereType` for a stream. |
| |
| # Getting a `StreamTransformer` instance |
| |
| It may be useful to pass an instance of `StreamTransformer` so that it can be |
| used with `stream.transform` calls rather than reference the specific operator |
| in place. Any operator on `Stream` that returns a `Stream` can be modeled as a |
| `StreamTransformer` using the [`fromBind` constructor][fromBind]. |
| |
| ```dart |
| final debounce = StreamTransformer.fromBind( |
| (s) => s.debounce(const Duration(milliseconds: 100))); |
| ``` |
| |
| [fromBind]: https://api.dart.dev/stable/dart-async/StreamTransformer/StreamTransformer.fromBind.html |
