Language/Statements/Continue/stream_utils.dart

// Copyright (c) 2015, 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.

/// @author a.semenov@unipro.ru

import 'dart:async';

Stream makeStream(Iterable iterable, {Function? beforeCancel()?: null}) {
  Stream s = new Stream.fromIterable(iterable);
  return new _StreamWrapper(s, beforeCancel);
}

class _StreamWrapper extends Stream {
  late Stream _stream;
  Function? _beforeCancel;
  _StreamWrapper(this._stream, this._beforeCancel);

  @override
  StreamSubscription listen(void onData(event)?,
  {Function? onError, void onDone()?, bool? cancelOnError}) {
  StreamSubscription s =_stream.listen(onData, onError:onError,
  onDone:onDone, cancelOnError: cancelOnError);
    return new _StreamSubscriptionWrapper(s, _beforeCancel);
  }
}

class _StreamSubscriptionWrapper implements StreamSubscription {
  StreamSubscription _streamSubscription;
  Function? _beforeCancel;
  _StreamSubscriptionWrapper(this._streamSubscription, this._beforeCancel);

  @override
  Future<E> asFuture<E>([E? futureValue]) {
    return _streamSubscription.asFuture(futureValue);
  }

  @override
  Future cancel() {
    if (_beforeCancel != null) {
      (_beforeCancel as Function)();
    }
    return _streamSubscription.cancel();
  }

  @override
  bool get isPaused => _streamSubscription.isPaused;

  @override
  void onData(void handleData(data)?) {
    _streamSubscription.onData(handleData);
  }

  @override
  void onDone(void handleDone()?) {
    _streamSubscription.onDone( handleDone);
  }

  @override
  void onError(Function? handleError) {
    _streamSubscription.onError(handleError);
  }

  @override
  void pause([Future? resumeSignal]) {
    _streamSubscription.pause(resumeSignal);
  }

  @override
  void resume() {
    _streamSubscription.resume();
  }
}