Modernize the package's style.

lib/result.dart

Index: lib/result.dart
diff --git a/lib/result.dart b/lib/result.dart
index 13e3dd94b288d8e579f3cc8a77eb88430f179356..627f2008b159246177dbc945c9457eecc6d8a8ec 100644
--- a/lib/result.dart
+++ b/lib/result.dart
@@ -2,255 +2,12 @@
 // 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.
 
-/// Capture asynchronous results into synchronous values.
-///
-/// Capturing a result (either a returned value or a thrown error)
-/// means converting it into a [Result] -
-/// either a [ValueResult] or an [ErrorResult].
-///
-/// This value can release itself by writing itself either to a
-/// [EventSink] or a [Completer], or by becoming a [Future].
+/// Import `async.dart` instead.
+@Deprecated("Will be removed in async 2.0.0.")
 library dart.pkg.async.results;
 
-import "dart:async";
-
-/// The result of a computation.
-abstract class Result<T> {
-  /// Create a `Result` with the result of calling [computation].
-  ///
-  /// This generates either a [ValueResult] with the value returned by
-  /// calling `computation`, or an [ErrorResult] with an error thrown by
-  /// the call.
-  factory Result(T computation()) {
-    try {
-      return new ValueResult(computation());
-    } catch (e, s) {
-      return new ErrorResult(e, s);
-    }
-  }
-
-  /// Create a `Result` holding a value.
-  ///
-  /// Alias for [ValueResult.ValueResult].
-  factory Result.value(T value) = ValueResult<T>;
-
-  /// Create a `Result` holding an error.
-  ///
-  /// Alias for [ErrorResult.ErrorResult].
-  factory Result.error(Object error, [StackTrace stackTrace]) =>
-      new ErrorResult(error, stackTrace);
-
-  // Helper functions.
-  static _captureValue(value) => new ValueResult(value);
-  static _captureError(error, stack) => new ErrorResult(error, stack);
-  static _release(Result v) {
-    if (v.isValue) return v.asValue.value;  // Avoid wrapping in future.
-    return v.asFuture;
-  }
-
-  /// Capture the result of a future into a `Result` future.
-  ///
-  /// The resulting future will never have an error.
-  /// Errors have been converted to an [ErrorResult] value.
-  static Future<Result> capture(Future future) {
-    return future.then(_captureValue, onError: _captureError);
-  }
-
-  /// Release the result of a captured future.
-  ///
-  /// Converts the [Result] value of the given [future] to a value or error
-  /// completion of the returned future.
-  ///
-  /// If [future] completes with an error, the returned future completes with
-  /// the same error.
-  static Future release(Future<Result> future) {
-    return future.then(_release);
-  }
-
-  /// Capture the results of a stream into a stream of [Result] values.
-  ///
-  /// The returned stream will not have any error events.
-  /// Errors from the source stream have been converted to [ErrorResult]s.
-  ///
-  /// Shorthand for transforming the stream using [CaptureStreamTransformer].
-  static Stream<Result> captureStream(Stream source) {
-    return source.transform(const CaptureStreamTransformer());
-  }
-
-  /// Release a stream of [result] values into a stream of the results.
-  ///
-  /// `Result` values of the source stream become value or error events in
-  /// the returned stream as appropriate.
-  /// Errors from the source stream become errors in the returned stream.
-  ///
-  /// Shorthand for transforming the stream using [ReleaseStreamTransformer].
-  static Stream releaseStream(Stream<Result> source) {
-    return source.transform(const ReleaseStreamTransformer());
-  }
-
-  /// Converts a result of a result to a single result.
-  ///
-  /// If the result is an error, or it is a `Result` value
-  /// which is then an error, then a result with that error is returned.
-  /// Otherwise both levels of results are value results, and a single
-  /// result with the value is returned.
-  static Result flatten(Result<Result> result) {
-    if (result.isError) return result;
-    return result.asValue.value;
-  }
-
-  /// Whether this result is a value result.
-  ///
-  /// Always the opposite of [isError].
-  bool get isValue;
-
-  /// Whether this result is an error result.
-  ///
-  /// Always the opposite of [isValue].
-  bool get isError;
-
-  /// If this is a value result, return itself.
-  ///
-  /// Otherwise return `null`.
-  ValueResult<T> get asValue;
-
-  /// If this is an error result, return itself.
-  ///
-  /// Otherwise return `null`.
-  ErrorResult get asError;
-
-  /// Complete a completer with this result.
-  void complete(Completer<T> completer);
-
-  /// Add this result to an [EventSink].
-  ///
-  /// Calls the sink's `add` or `addError` method as appropriate.
-  void addTo(EventSink<T> sink);
-
-  /// Creates a future completed with this result as a value or an error.
-  Future<T> get asFuture;
-}
-
-/// A result representing a returned value.
-class ValueResult<T> implements Result<T> {
-  final T value;
-  ValueResult(this.value);
-  bool get isValue => true;
-  bool get isError => false;
-  ValueResult<T> get asValue => this;
-  ErrorResult get asError => null;
-  void complete(Completer<T> completer) {
-    completer.complete(value);
-  }
-  void addTo(EventSink<T> sink) {
-    sink.add(value);
-  }
-  Future<T> get asFuture => new Future.value(value);
-}
-
-/// A result representing a thrown error.
-class ErrorResult implements Result {
-  final error;
-  final StackTrace stackTrace;
-  ErrorResult(this.error, this.stackTrace);
-  bool get isValue => false;
-  bool get isError => true;
-  ValueResult get asValue => null;
-  ErrorResult get asError => this;
-  void complete(Completer completer) {
-    completer.completeError(error, stackTrace);
-  }
-  void addTo(EventSink sink) {
-    sink.addError(error, stackTrace);
-  }
-  Future get asFuture => new Future.error(error, stackTrace);
-
-  /// Calls an error handler with the error and stacktrace.
-  ///
-  /// An async error handler function is either a function expecting two
-  /// arguments, which will be called with the error and the stack trace,
-  /// or it has to be a function expecting only one argument,
-  /// which will be called with only the error.
-  void handle(Function errorHandler) {
-    if (errorHandler is ZoneBinaryCallback) {
-      errorHandler(error, stackTrace);
-    } else {
-      errorHandler(error);
-    }
-  }
-}
-
-/// 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.
-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);
-  }
-
-  static EventSink _createSink(EventSink<Result> sink) {
-    return new CaptureSink(sink);
-  }
-}
-
-/// A stream transformer that releases a stream of result events.
-///
-/// The result of the transformation is a stream of values and
-/// error events.
-class ReleaseStreamTransformer<T> implements StreamTransformer<Result<T>, T> {
-  const ReleaseStreamTransformer();
-
-  Stream<T> bind(Stream<Result<T>> source) {
-    return new Stream<T>.eventTransformed(source, _createSink);
-  }
-
-  static EventSink<Result> _createSink(EventSink sink) {
-    return new ReleaseSink(sink);
-  }
-}
-
-/// An event sink wrapper that captures the incoming events.
-///
-/// Wraps an [EventSink] that expects [Result] values.
-/// Accepts any value and error result,
-/// and passes them to the wrapped sink as [Result] values.
-///
-/// The wrapped sink will never receive an error event.
-class CaptureSink<T> implements EventSink<T> {
-  final EventSink _sink;
-
-  CaptureSink(EventSink<Result<T>> sink) : _sink = sink;
-  void add(T value) { _sink.add(new ValueResult(value)); }
-  void addError(Object error, [StackTrace stackTrace]) {
-    _sink.add(new ErrorResult(error, stackTrace));
-  }
-  void close() { _sink.close(); }
-}
-
-/// An event sink wrapper that releases the incoming result events.
-///
-/// Wraps an output [EventSink] that expects any result.
-/// Accepts [Result] values, and puts the result value or error into the
-/// corresponding output sink add method.
-class ReleaseSink<T> implements EventSink<Result<T>> {
-  final EventSink _sink;
-  ReleaseSink(EventSink<T> sink) : _sink = sink;
-  void add(Result<T> result) {
-    if (result.isValue) {
-      _sink.add(result.asValue.value);
-    } else {
-      ErrorResult error = result.asError;
-      _sink.addError(error.error, error.stackTrace);
-    }
-  }
-  void addError(Object error, [StackTrace stackTrace]) {
-    // Errors may be added by intermediate processing, even if it is never
-    // added by CaptureSink.
-    _sink.addError(error, stackTrace);
-  }
-
-  void close() { _sink.close(); }
-}
+export "src/result.dart";
+export "src/result/capture_transformer.dart";
+export "src/result/error.dart";
+export "src/result/release_transformer.dart";
+export "src/result/value.dart";