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45 lines
1.4 KiB
Dart
45 lines
1.4 KiB
Dart
// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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/// A class for making time based operations testable.
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class SystemClock {
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/// A const constructor to allow subclasses to be const.
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const SystemClock();
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/// Create a clock with a fixed current time.
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const factory SystemClock.fixed(DateTime time) = _FixedTimeClock;
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/// Retrieve the current time.
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DateTime now() => DateTime.now();
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/// Compute the time a given duration ago.
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DateTime ago(Duration duration) {
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return now().subtract(duration);
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}
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}
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class _FixedTimeClock extends SystemClock {
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const _FixedTimeClock(this._fixedTime);
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final DateTime _fixedTime;
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@override
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DateTime now() => _fixedTime;
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}
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/// Format time as 'yyyy-MM-dd HH:mm:ss Z' where Z is the difference between the
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/// timezone of t and UTC formatted according to RFC 822.
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String formatDateTime(DateTime t) {
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final String sign = t.timeZoneOffset.isNegative ? '-' : '+';
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final Duration tzOffset = t.timeZoneOffset.abs();
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final int hoursOffset = tzOffset.inHours;
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final int minutesOffset =
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tzOffset.inMinutes - (Duration.minutesPerHour * hoursOffset);
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assert(hoursOffset < 24);
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assert(minutesOffset < 60);
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String twoDigits(int n) => (n >= 10) ? '$n' : '0$n';
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return '$t $sign${twoDigits(hoursOffset)}${twoDigits(minutesOffset)}';
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}
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