| Index: mojo/public/dart/third_party/barback/lib/src/utils.dart
|
| diff --git a/mojo/public/dart/third_party/barback/lib/src/utils.dart b/mojo/public/dart/third_party/barback/lib/src/utils.dart
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| new file mode 100644
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| index 0000000000000000000000000000000000000000..7ce6724e17c31d67239f2754e61c1757c2532b1e
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| --- /dev/null
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| +++ b/mojo/public/dart/third_party/barback/lib/src/utils.dart
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| @@ -0,0 +1,347 @@
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| +// 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 barback.utils;
|
| +
|
| +import 'dart:async';
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| +import 'dart:typed_data';
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| +
|
| +import 'package:stack_trace/stack_trace.dart';
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| +
|
| +/// A class that represents a value or an error.
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| +class Fallible<E> {
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| + /// Whether [this] has a [value], as opposed to an [error].
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| + final bool hasValue;
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| +
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| + /// Whether [this] has an [error], as opposed to a [value].
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| + bool get hasError => !hasValue;
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| +
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| + /// The value.
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| + ///
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| + /// This will be `null` if [this] has an [error].
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| + final E _value;
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| +
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| + /// The value.
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| + ///
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| + /// This will throw a [StateError] if [this] has an [error].
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| + E get value {
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| + if (hasValue) return _value;
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| + throw new StateError("Fallible has no value.\n"
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| + "$_error$_stackTraceSuffix");
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| + }
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| +
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| + /// The error.
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| + ///
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| + /// This will be `null` if [this] has a [value].
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| + final _error;
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| +
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| + /// The error.
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| + ///
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| + /// This will throw a [StateError] if [this] has a [value].
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| + get error {
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| + if (hasError) return _error;
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| + throw new StateError("Fallible has no error.");
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| + }
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| +
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| + /// The stack trace for [_error].
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| + ///
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| + /// This will be `null` if [this] has a [value], or if no stack trace was
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| + /// provided.
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| + final StackTrace _stackTrace;
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| +
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| + /// The stack trace for [error].
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| + ///
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| + /// This will throw a [StateError] if [this] has a [value].
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| + StackTrace get stackTrace {
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| + if (hasError) return _stackTrace;
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| + throw new StateError("Fallible has no error.");
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| + }
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| +
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| + Fallible.withValue(this._value)
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| + : _error = null,
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| + _stackTrace = null,
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| + hasValue = true;
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| +
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| + Fallible.withError(this._error, [this._stackTrace])
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| + : _value = null,
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| + hasValue = false;
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| +
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| + /// Returns a completed Future with the same value or error as [this].
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| + Future toFuture() {
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| + if (hasValue) return new Future.value(value);
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| + return new Future.error(error, stackTrace);
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| + }
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| +
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| + String toString() {
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| + if (hasValue) return "Fallible value: $value";
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| + return "Fallible error: $error$_stackTraceSuffix";
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| + }
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| +
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| + String get _stackTraceSuffix {
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| + if (stackTrace == null) return "";
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| + return "\nStack trace:\n${new Chain.forTrace(_stackTrace).terse}";
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| + }
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| +}
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| +
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| +/// Converts a number in the range [0-255] to a two digit hex string.
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| +///
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| +/// For example, given `255`, returns `ff`.
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| +String byteToHex(int byte) {
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| + assert(byte >= 0 && byte <= 255);
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| +
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| + const DIGITS = "0123456789abcdef";
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| + return DIGITS[(byte ~/ 16) % 16] + DIGITS[byte % 16];
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| +}
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| +
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| +/// Returns a sentence fragment listing the elements of [iter].
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| +///
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| +/// This converts each element of [iter] to a string and separates them with
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| +/// commas and/or "and" where appropriate.
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| +String toSentence(Iterable iter) {
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| + if (iter.length == 1) return iter.first.toString();
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| + return iter.take(iter.length - 1).join(", ") + " and ${iter.last}";
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| +}
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| +
|
| +/// Returns [name] if [number] is 1, or the plural of [name] otherwise.
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| +///
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| +/// By default, this just adds "s" to the end of [name] to get the plural. If
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| +/// [plural] is passed, that's used instead.
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| +String pluralize(String name, int number, {String plural}) {
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| + if (number == 1) return name;
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| + if (plural != null) return plural;
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| + return '${name}s';
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| +}
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| +
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| +/// Converts [input] into a [Uint8List].
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| +///
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| +/// If [input] is a [TypedData], this just returns a view on [input].
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| +Uint8List toUint8List(List<int> input) {
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| + if (input is Uint8List) return input;
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| + if (input is TypedData) {
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| + // TODO(nweiz): remove "as" when issue 11080 is fixed.
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| + return new Uint8List.view((input as TypedData).buffer);
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| + }
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| + return new Uint8List.fromList(input);
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| +}
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| +
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| +/// Group the elements in [iter] by the value returned by [fn].
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| +///
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| +/// This returns a map whose keys are the return values of [fn] and whose values
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| +/// are lists of each element in [iter] for which [fn] returned that key.
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| +Map<Object, List> groupBy(Iterable iter, fn(element)) {
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| + var map = {};
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| + for (var element in iter) {
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| + var list = map.putIfAbsent(fn(element), () => []);
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| + list.add(element);
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| + }
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| + return map;
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| +}
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| +
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| +/// Flattens nested lists inside an iterable into a single list containing only
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| +/// non-list elements.
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| +List flatten(Iterable nested) {
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| + var result = [];
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| + helper(list) {
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| + for (var element in list) {
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| + if (element is List) {
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| + helper(element);
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| + } else {
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| + result.add(element);
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| + }
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| + }
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| + }
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| + helper(nested);
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| + return result;
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| +}
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| +
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| +/// Returns the union of all elements in each set in [sets].
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| +Set unionAll(Iterable<Set> sets) =>
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| + sets.fold(new Set(), (union, set) => union.union(set));
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| +
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| +/// Creates a new map from [map] with new keys and values.
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| +///
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| +/// The return values of [keyFn] are used as the keys and the return values of
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| +/// [valueFn] are used as the values for the new map.
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| +Map mapMap(Map map, keyFn(key, value), valueFn(key, value)) =>
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| + new Map.fromIterable(map.keys,
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| + key: (key) => keyFn(key, map[key]),
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| + value: (key) => valueFn(key, map[key]));
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| +
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| +/// Creates a new map from [map] with the same keys.
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| +///
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| +/// The return values of [fn] are used as the values for the new map.
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| +Map mapMapValues(Map map, fn(key, value)) => mapMap(map, (key, _) => key, fn);
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| +
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| +/// Creates a new map from [map] with the same keys.
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| +///
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| +/// The return values of [fn] are used as the keys for the new map.
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| +Map mapMapKeys(Map map, fn(key, value)) => mapMap(map, fn, (_, value) => value);
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| +
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| +/// Returns whether [set1] has exactly the same elements as [set2].
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| +bool setEquals(Set set1, Set set2) =>
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| + set1.length == set2.length && set1.containsAll(set2);
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| +
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| +/// Merges [streams] into a single stream that emits events from all sources.
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| +///
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| +/// If [broadcast] is true, this will return a broadcast stream; otherwise, it
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| +/// will return a buffered stream.
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| +Stream mergeStreams(Iterable<Stream> streams, {bool broadcast: false}) {
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| + streams = streams.toList();
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| + var doneCount = 0;
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| + // Use a sync stream to preserve the synchrony behavior of the input streams.
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| + // If the inputs are sync, then this will be sync as well; if the inputs are
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| + // async, then the events we receive will also be async, and forwarding them
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| + // sync won't change that.
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| + var controller = broadcast ? new StreamController.broadcast(sync: true)
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| + : new StreamController(sync: true);
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| +
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| + for (var stream in streams) {
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| + stream.listen(
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| + controller.add,
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| + onError: controller.addError,
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| + onDone: () {
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| + doneCount++;
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| + if (doneCount == streams.length) controller.close();
|
| + });
|
| + }
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| +
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| + return controller.stream;
|
| +}
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| +
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| +/// Prepends each line in [text] with [prefix]. If [firstPrefix] is passed, the
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| +/// first line is prefixed with that instead.
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| +String prefixLines(String text, {String prefix: '| ', String firstPrefix}) {
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| + var lines = text.split('\n');
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| + if (firstPrefix == null) {
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| + return lines.map((line) => '$prefix$line').join('\n');
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| + }
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| +
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| + var firstLine = "$firstPrefix${lines.first}";
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| + lines = lines.skip(1).map((line) => '$prefix$line').toList();
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| + lines.insert(0, firstLine);
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| + return lines.join('\n');
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| +}
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| +
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| +/// Returns a [Future] that completes after pumping the event queue [times]
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| +/// times. By default, this should pump the event queue enough times to allow
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| +/// any code to run, as long as it's not waiting on some external event.
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| +Future pumpEventQueue([int times=20]) {
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| + if (times == 0) return new Future.value();
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| + // We use a delayed future to allow microtask events to finish. The
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| + // Future.value or Future() constructors use scheduleMicrotask themselves and
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| + // would therefore not wait for microtask callbacks that are scheduled after
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| + // invoking this method.
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| + return new Future.delayed(Duration.ZERO, () => pumpEventQueue(times - 1));
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| +}
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| +
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| +/// Like `new Future`, but avoids issue 11911 by using `new Future.value` under
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| +/// the covers.
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| +// TODO(jmesserly): doc comment changed to due 14601.
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| +Future newFuture(callback()) => new Future.value().then((_) => callback());
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| +
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| +/// Like [Future.sync], but wraps the Future in [Chain.track] as well.
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| +Future syncFuture(callback()) => Chain.track(new Future.sync(callback));
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| +
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| +/// Returns a buffered stream that will emit the same values as the stream
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| +/// returned by [future] once [future] completes.
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| +///
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| +/// If [future] completes to an error, the return value will emit that error and
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| +/// then close.
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| +///
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| +/// If [broadcast] is true, a broadcast stream is returned. This assumes that
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| +/// the stream returned by [future] will be a broadcast stream as well.
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| +/// [broadcast] defaults to false.
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| +Stream futureStream(Future<Stream> future, {bool broadcast: false}) {
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| + var subscription;
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| + var controller;
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| +
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| + future = future.catchError((e, stackTrace) {
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| + // Since [controller] is synchronous, it's likely that emitting an error
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| + // will cause it to be cancelled before we call close.
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| + if (controller != null) controller.addError(e, stackTrace);
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| + if (controller != null) controller.close();
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| + controller = null;
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| + });
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| +
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| + onListen() {
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| + future.then((stream) {
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| + if (controller == null) return;
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| + subscription = stream.listen(
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| + controller.add,
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| + onError: controller.addError,
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| + onDone: controller.close);
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| + });
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| + }
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| +
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| + onCancel() {
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| + if (subscription != null) subscription.cancel();
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| + subscription = null;
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| + controller = null;
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| + }
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| +
|
| + if (broadcast) {
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| + controller = new StreamController.broadcast(
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| + sync: true, onListen: onListen, onCancel: onCancel);
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| + } else {
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| + controller = new StreamController(
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| + sync: true, onListen: onListen, onCancel: onCancel);
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| + }
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| + return controller.stream;
|
| +}
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| +
|
| +/// Returns a [Stream] that will emit the same values as the stream returned by
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| +/// [callback].
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| +///
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| +/// [callback] will only be called when the returned [Stream] gets a subscriber.
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| +Stream callbackStream(Stream callback()) {
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| + var subscription;
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| + var controller;
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| + controller = new StreamController(onListen: () {
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| + subscription = callback().listen(controller.add,
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| + onError: controller.addError,
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| + onDone: controller.close);
|
| + },
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| + onCancel: () => subscription.cancel(),
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| + onPause: () => subscription.pause(),
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| + onResume: () => subscription.resume(),
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| + sync: true);
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| + return controller.stream;
|
| +}
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| +
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| +/// Creates a single-subscription stream from a broadcast stream.
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| +///
|
| +/// The returned stream will enqueue events from [broadcast] until a listener is
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| +/// attached, then pipe events to that listener.
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| +Stream broadcastToSingleSubscription(Stream broadcast) {
|
| + if (!broadcast.isBroadcast) return broadcast;
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| +
|
| + // TODO(nweiz): Implement this using a transformer when issues 18588 and 18586
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| + // are fixed.
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| + var subscription;
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| + var controller = new StreamController(onCancel: () => subscription.cancel());
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| + subscription = broadcast.listen(controller.add,
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| + onError: controller.addError,
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| + onDone: controller.close);
|
| + return controller.stream;
|
| +}
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| +
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| +/// A regular expression to match the exception prefix that some exceptions'
|
| +/// [Object.toString] values contain.
|
| +final _exceptionPrefix = new RegExp(r'^([A-Z][a-zA-Z]*)?(Exception|Error): ');
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| +
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| +/// Get a string description of an exception.
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| +///
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| +/// Many exceptions include the exception class name at the beginning of their
|
| +/// [toString], so we remove that if it exists.
|
| +String getErrorMessage(error) =>
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| + error.toString().replaceFirst(_exceptionPrefix, '');
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| +
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| +/// Returns a human-friendly representation of [duration].
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| +String niceDuration(Duration duration) {
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| + var result = duration.inMinutes > 0 ? "${duration.inMinutes}:" : "";
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| +
|
| + var s = duration.inSeconds % 59;
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| + var ms = (duration.inMilliseconds % 1000) ~/ 100;
|
| + return result + "$s.${ms}s";
|
| +}
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|
|