lib/src/result/capture_transformer.dart

// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';

import 'result.dart';
import 'capture_sink.dart';

/// A stream transformer that captures a stream of events into [Result]s.
///
/// The result of the transformation is a stream of [Result] values and no
/// error events. Exposed by [Result.captureStream].
class CaptureStreamTransformer<T> implements StreamTransformer<T, Result<T>> {
  const CaptureStreamTransformer();

  Stream<Result<T>> bind(Stream<T> source) {
    return new Stream<Result<T>>.eventTransformed(source, _createSink);
  }

  // Since Stream.eventTransformed is not generic, this method can be static.
  static EventSink _createSink(EventSink<Result> sink) => new CaptureSink(sink);
}