StreamTransformer class - dart:async library (original) (raw)

Transforms a Stream.

When a stream's Stream.transform method is invoked with aStreamTransformer, the stream calls the bind method on the provided transformer. The resulting stream is then returned from theStream.transform method.

Conceptually, a transformer is simply a function from Stream to Streamthat is encapsulated into a class.

It is good practice to write transformers that can be used multiple times.

All other transforming methods on Stream, such as Stream.map,Stream.where or Stream.expand can be implemented usingStream.transform. A StreamTransformer is thus very powerful but often also a bit more complicated to use.

The StreamTransformer.fromHandlers constructor allows passing separate callbacks to react to events, errors, and the end of the stream. The StreamTransformer.fromBind constructor creates a StreamTransformerwhose bind method is implemented by calling the function passed to the constructor.

Implementers

• StreamTransformerBase
• WebSocketTransformer

Constructors

StreamTransformer(StreamSubscription<T> onListen(Stream<S> stream, bool cancelOnError))

Creates a StreamTransformer based on the given onListen callback.

const

factory

StreamTransformer.fromBind(Stream<T> bind(Stream<S>))

Creates a StreamTransformer based on a bind callback.

factory

StreamTransformer.fromHandlers({void handleData(S data, EventSink<T> sink)?, void handleError(Object error, StackTrace stackTrace, EventSink<T> sink)?, void handleDone(EventSink<T> sink)?})

Creates a StreamTransformer that delegates events to the given functions.

factory

Properties

hashCode → int

The hash code for this object.

no setterinherited

runtimeType → Type

A representation of the runtime type of the object.

no setterinherited

Methods

bind(Stream<S> stream)→ Stream<T>

Transforms the provided stream.

cast<RS, RT>()→ StreamTransformer<RS, RT>

Provides a StreamTransformer<RS, RT> view of this stream transformer.

noSuchMethod(Invocation invocation)→ dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString()→ String

A string representation of this object.

inherited

Operators

operator ==(Object other)→ bool

The equality operator.

inherited

Static Methods

castFrom<SS, ST, TS, TT>(StreamTransformer<SS, ST> source)→ StreamTransformer<TS, TT>

Adapts source to be a StreamTransformer<TS, TT>.