Utility methods to create
StreamTransfomer instances to manipulate Streams.
asyncMap but events are buffered in a List until previous events have
been processed rather than being called for each element individually.
asyncMap but events are discarded, keeping only the latest, until
previous events have been processed rather than being called for every element.
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.
Collects values from a source stream until a
trigger stream fires and the
collected values are emitted.
Combine the most recent event from two streams through a callback and emit the result.
Combines the latest events emitted from multiple source streams and yields a list of the values.
debounce, debounceBuffer #
Prevents a source stream from emitting too frequently by dropping or collecting values that occur within a given duration.
asyncMap but the convert callback can be called with subsequent values
before it has finished for previous values.
Appends the values of a stream after another stream finishes.
merge, mergeAll #
Interleaves events from multiple streams into a single stream.
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
Let values through until a Future fires.
Taps into a single-subscriber stream to react to values as they pass, without being a real subscriber.
Blocks events for a duration after an event is successfully emitted.
Iterable.whereType for a stream.
- Internal cleanup. Passed "trigger" streams or futures now allow
<void>generic type rather than an implicit
- Add concrete types to the
- Remove usage of Set literal which is not available before Dart 2.2.0
- Allow a
combinecallback to return a
scan. There are no behavior changes for synchronous callbacks. Potential breaking change In the unlikely situation where
scanwas used to produce a
Stream<Future>inference may now fail and require explicit generic type arguments.
- Allow using non-dev Dart 2 SDK.
asyncWherewill now forward exceptions thrown by the callback through the result Stream.
mergeAllnow accepts an
Iterable<Stream>instead of only
mapfor use cases where
StreamTransformerinstances are stored as variables or passed to methods other than
followedByto match the naming of
concatis now deprecated.
Updates to support Dart 2.0 core library changes (wave 2.2). See issue 31847 for details.
- Bug Fix: Streams produced with
switchMapnow correctly report
- Bug Fix: Some transformers did not correctly add data to all listeners on
broadcast streams. Fixed for
- Bug Fix: Only call the
tapdata callback once per event rather than once per listener.
- Bug Fix: Allow canceling and re-listening to broadcast streams after a
- Bug Fix: Broadcast streams which are buffered using a single-subscription trigger can be canceled and re-listened.
- Bug Fix: Buffer outputs one more value if there is a pending trigger before the trigger closes.
- Bug Fix: Single-subscription streams concatted after broadcast streams are handled correctly.
- Use sync
StreamControllersfor forwarding where possible.
- Bug Fix: Allow compiling switchLatest with Dart2Js.
wherebut allows an asynchronous predicate.
scan: fold which returns intermediate values
throttle: block events for a duration after emitting a value
audit: emits the last event received after a duration
tap: React to values as they pass without being a subscriber on a stream
switchLatest: Flatten a Stream of Streams into a Stream which forwards values from the most recent Stream
concat: Appends streams in series
mergeAll: Interleaves streams
- Initial release with the following utilities:
buffer: Collects events in a
debounceBuffer: Collect or drop events which occur closer in time than a given duration.
Use this package as a library
1. Depend on it
Add this to your package's pubspec.yaml file:
dependencies: stream_transform: ^0.0.19
2. Install it
You can install packages from the command line:
$ pub get
$ flutter pub get
Alternatively, your editor might support
pub get or
flutter pub get.
Check the docs for your editor to learn more.
3. Import it
Now in your Dart code, you can use:
Describes how popular the package is relative to other packages. [more]
Code health derived from static analysis. [more]
Reflects how tidy and up-to-date the package is. [more]
Weighted score of the above. [more]
We analyzed this package on Sep 17, 2019, and provided a score, details, and suggestions below. Analysis was completed with status completed using:
- Dart: 2.5.0
- pana: 0.12.21
Detected platforms: Flutter, web, other
No platform restriction found in primary library
Maintain an example. (-10 points)
Create a short demo in the
example/ directory to show how to use this package.
Common filename patterns include
stream_transform.dart. Packages with multiple examples should provide
For more information see the pub package layout conventions.
Package is pre-v0.1 release. (-10 points)
While nothing is inherently wrong with versions of
0.0.*, it might mean that the author is still experimenting with the general direction of the API.