| // Copyright (c) 2013, 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. |
| |
| library utils; |
| |
| import 'dart:async'; |
| |
| /// A pair of values. |
| class Pair<E, F> { |
| E first; |
| F last; |
| |
| Pair(this.first, this.last); |
| |
| String toString() => '($first, $last)'; |
| |
| bool operator==(other) { |
| if (other is! Pair) return false; |
| return other.first == first && other.last == last; |
| } |
| |
| int get hashCode => first.hashCode ^ last.hashCode; |
| } |
| |
| /// Configures [future] so that its result (success or exception) is passed on |
| /// to [completer]. |
| void chainToCompleter(Future future, Completer completer) { |
| future.then((value) => completer.complete(value), |
| onError: (e) => completer.completeError(e)); |
| } |
| |
| /// Prepends each line in [text] with [prefix]. If [firstPrefix] is passed, the |
| /// first line is prefixed with that instead. |
| String prefixLines(String text, {String prefix: '| ', String firstPrefix}) { |
| var lines = text.split('\n'); |
| if (firstPrefix == null) { |
| return lines.map((line) => '$prefix$line').join('\n'); |
| } |
| |
| var firstLine = "$firstPrefix${lines.first}"; |
| lines = lines.skip(1).map((line) => '$prefix$line').toList(); |
| lines.insert(0, firstLine); |
| return lines.join('\n'); |
| } |
| |
| /// Returns a [Future] that completes after pumping the event queue [times] |
| /// times. By default, this should pump the event queue enough times to allow |
| /// any code to run, as long as it's not waiting on some external event. |
| Future pumpEventQueue([int times=20]) { |
| if (times == 0) return new Future.immediate(null); |
| return new Future.immediate(null).then((_) => pumpEventQueue(times - 1)); |
| } |
| |
| /// Returns whether [iterable1] has the same elements in the same order as |
| /// [iterable2]. The elements are compared using `==`. |
| bool orderedIterableEquals(Iterable iterable1, Iterable iterable2) { |
| var iter1 = iterable1.iterator; |
| var iter2 = iterable2.iterator; |
| |
| while (true) { |
| var hasNext1 = iter1.moveNext(); |
| var hasNext2 = iter2.moveNext(); |
| if (hasNext1 != hasNext2) return false; |
| if (!hasNext1) return true; |
| if (iter1.current != iter2.current) return false; |
| } |
| } |
| |
| // TODO(nweiz): remove this when issue 8731 is fixed. |
| /// Returns a [Stream] that will immediately emit [error] and then close. |
| Stream errorStream(error) => new Future.immediateError(error).asStream(); |
| |
| /// Returns a buffered stream that will emit the same values as the stream |
| /// returned by [future] once [future] completes. If [future] completes to an |
| /// error, the return value will emit that error and then close. |
| Stream futureStream(Future<Stream> future) { |
| var controller = new StreamController(); |
| future.then((stream) { |
| stream.listen( |
| controller.add, |
| onError: (error) => controller.addError(error), |
| onDone: controller.close); |
| }).catchError((e) { |
| controller.addError(e); |
| controller.close(); |
| }); |
| return controller.stream; |
| } |
| |
| // TODO(nweiz): remove this when issue 7964 is fixed. |
| /// Returns a [Future] that will complete to the first element of [stream]. |
| /// Unlike [Stream.first], this is safe to use with single-subscription streams. |
| Future streamFirst(Stream stream) { |
| var stackTrace; |
| try { |
| throw ''; |
| } catch (_, thrownStackTrace) { |
| stackTrace = thrownStackTrace; |
| } |
| |
| var completer = new Completer(); |
| var subscription; |
| subscription = stream.listen((value) { |
| subscription.cancel(); |
| completer.complete(value); |
| }, onError: (e) { |
| completer.completeError(e.error, e.stackTrace); |
| }, onDone: () { |
| completer.completeError(new StateError("No elements"), stackTrace); |
| }, unsubscribeOnError: true); |
| return completer.future; |
| } |
| |
| /// A function that can be called to cancel a [Stream] and send a done message. |
| typedef void StreamCanceller(); |
| |
| // TODO(nweiz): use a StreamSubscription when issue 9026 is fixed. |
| /// Returns a wrapped version of [stream] along with a function that will cancel |
| /// the wrapped stream. Unlike [StreamSubscription], this canceller will send a |
| /// "done" message to the wrapped stream. |
| Pair<Stream, StreamCanceller> streamWithCanceller(Stream stream) { |
| var controller = stream.isBroadcast ? |
| new StreamController.broadcast() : |
| new StreamController(); |
| var subscription = stream.listen((value) { |
| if (!controller.isClosed) controller.add(value); |
| }, onError: (error) { |
| if (!controller.isClosed) controller.signalError(error); |
| }, onDone: controller.close); |
| return new Pair<Stream, StreamCanceller>(controller.stream, controller.close); |
| } |
| |
| // TODO(nweiz): remove this when issue 7787 is fixed. |
| /// Creates two single-subscription [Stream]s that each emit all values and |
| /// errors from [stream]. This is useful if [stream] is single-subscription but |
| /// multiple subscribers are necessary. |
| Pair<Stream, Stream> tee(Stream stream) { |
| var controller1 = new StreamController(); |
| var controller2 = new StreamController(); |
| stream.listen((value) { |
| controller1.add(value); |
| controller2.add(value); |
| }, onError: (error) { |
| controller1.signalError(error); |
| controller2.signalError(error); |
| }, onDone: () { |
| controller1.close(); |
| controller2.close(); |
| }); |
| return new Pair<Stream, Stream>(controller1.stream, controller2.stream); |
| } |
| |
| /// Takes a simple data structure (composed of [Map]s, [Iterable]s, scalar |
| /// objects, and [Future]s) and recursively resolves all the [Future]s contained |
| /// within. Completes with the fully resolved structure. |
| Future awaitObject(object) { |
| // Unroll nested futures. |
| if (object is Future) return object.then(awaitObject); |
| if (object is Iterable) { |
| return Future.wait(object.map(awaitObject).toList()); |
| } |
| if (object is! Map) return new Future.immediate(object); |
| |
| var pairs = <Future<Pair>>[]; |
| object.forEach((key, value) { |
| pairs.add(awaitObject(value) |
| .then((resolved) => new Pair(key, resolved))); |
| }); |
| return Future.wait(pairs).then((resolvedPairs) { |
| var map = {}; |
| for (var pair in resolvedPairs) { |
| map[pair.first] = pair.last; |
| } |
| return map; |
| }); |
| } |
| |
| /// Returns whether [pattern] matches all of [string]. |
| bool fullMatch(String string, Pattern pattern) { |
| var matches = pattern.allMatches(string); |
| if (matches.isEmpty) return false; |
| return matches.first.start == 0 && matches.first.end == string.length; |
| } |