Reapply "Sharing of sources for corelib date implementation between VM

corelib/unified/core/date.dart

-// Copyright (c) 2011, 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.
-
-// Dart core library.
-
-/**
- * Date is the public interface to a point in time.
- *
- * It can represent time values that are at a distance of at most
- * 8,640,000,000,000,000ms (100,000,000 days) from epoch (1970-01-01 UTC). In
- * other words: [:millisecondsSinceEpoch.abs() <= 8640000000000000:].
- *
- * Also see [Stopwatch] for means to measure time-spans.
- */
-interface Date extends Comparable, Hashable default DateImplementation {
-  // Weekday constants that are returned by [weekday] method:
-  static final int MON = 1;
-  static final int TUE = 2;
-  static final int WED = 3;
-  static final int THU = 4;
-  static final int FRI = 5;
-  static final int SAT = 6;
-  static final int SUN = 7;
-  static final int DAYS_IN_WEEK = 7;
-
-  // Month constants that are returned by the [month] getter.
-  static final int JAN = 1;
-  static final int FEB = 2;
-  static final int MAR = 3;
-  static final int APR = 4;
-  static final int MAY = 5;
-  static final int JUN = 6;
-  static final int JUL = 7;
-  static final int AUG = 8;
-  static final int SEP = 9;
-  static final int OCT = 10;
-  static final int NOV = 11;
-  static final int DEC = 12;
-
-  /**
-   * Constructs a [Date] instance based on the individual parts. The date is
-   * in the local time zone if [isUtc] is false.
-   *
-   * [month] and [day] are one-based. For example
-   * [:new Date(1938, 1, 10)] represents the 10th of January 1938.
-   */
-  // TODO(floitsch): the spec allows default values in interfaces, but our
-  // tools don't yet. Eventually we want to have default values here.
-  Date(int year,
-       [int month,
-        int day,
-        int hour,
-        int minute,
-        int second,
-        int millisecond,
-        bool isUtc]);
-
-  /**
-   * Constructs a new [Date] instance with current date time value in the
-   * local time zone.
-   */
-  Date.now();
-
-  /**
-   * Constructs a new [Date] instance based on [formattedString].
-   */
-  Date.fromString(String formattedString);
-
-  /**
-   * Constructs a new [Date] instance with the given [millisecondsSinceEpoch].
-   * If [isUtc] is false then the date is in the local time zone.
-   *
-   * The constructed [Date] represents
-   * 1970-01-01T00:00:00Z + [millisecondsSinceEpoch]ms in the given
-   * time zone (local or UTC).
-   */
-  // TODO(floitsch): the spec allows default values in interfaces, but our
-  // tools don't yet. Eventually we want to have default values here.
-  Date.fromMillisecondsSinceEpoch(int millisecondsSinceEpoch, [bool isUtc]);
-
-  /**
-   * Returns true if [this] occurs at the same time as [other]. The
-   * comparison is independent of whether the time is utc or in the local
-   * time zone.
-   */
-  bool operator ==(Date other);
-  /**
-   * Returns true if [this] occurs before [other]. The comparison is independent
-   * of whether the time is utc or in the local time zone.
-   */
-  bool operator <(Date other);
-  /**
-   * Returns true if [this] occurs at the same time or before [other]. The
-   * comparison is independent of whether the time is utc or in the local
-   * time zone.
-   */
-  bool operator <=(Date other);
-  /**
-   * Returns true if [this] occurs after [other]. The comparison is independent
-   * of whether the time is utc or in the local time zone.
-   */
-  bool operator >(Date other);
-  /**
-   * Returns true if [this] occurs at the same time or after [other]. The
-   * comparison is independent of whether the time is utc or in the local
-   * time zone.
-   */
-  bool operator >=(Date other);
-
-
-  /**
-   * Returns [this] in the local time zone. Returns itself if it is already in
-   * the local time zone. Otherwise, this method is equivalent to
-   * [:new Date.fromMillisecondsSinceEpoch(millisecondsSinceEpoch, false):].
-   */
-  Date toLocal();
-
-  /**
-   * Returns [this] in UTC. Returns itself if it is already in UTC. Otherwise,
-   * this method is equivalent to
-   * [:new Date.fromMillisecondsSinceEpoch(millisecondsSinceEpoch, true):].
-   */
-  Date toUtc();
-
-  /**
-   * Returns the abbreviated time-zone name.
-   *
-   * Examples: [:"CET":] or [:"CEST":].
-   */
-  String get timeZoneName();
-
-  /**
-   * The time-zone offset is the difference between local time and UTC. That is,
-   * the offset is positive for time zones west of UTC.
-   *
-   * Note, that JavaScript, Python and C return the difference between UTC and
-   * local time. Java, C# and Ruby return the difference between local time and
-   * UTC.
-   */
-  Duration get timeZoneOffset();
-
-  /**
-   * Returns the year.
-   */
-  int get year();
-
-  /**
-   * Returns the month into the year [1..12].
-   */
-  int get month();
-
-  /**
-   * Returns the day into the month [1..31].
-   */
-  int get day();
-
-  /**
-   * Returns the hour into the day [0..23].
-   */
-  int get hour();
-
-  /**
-   * Returns the minute into the hour [0...59].
-   */
-  int get minute();
-
-  /**
-   * Returns the second into the minute [0...59].
-   */
-  int get second();
-
-  /**
-   * Returns the millisecond into the second [0...999].
-   */
-  int get millisecond();
-
-  /**
-   * Returns the week day [MON..SUN]. In accordance with ISO 8601
-   * a week starts with Monday which has the value 1.
-   */
-  int get weekday();
-
-  /**
-   * The milliseconds since 1970-01-01T00:00:00Z (UTC). This value is
-   * independent of the time zone.
-   *
-   * See [Stopwatch] for means to measure time-spans.
-   */
-  int get millisecondsSinceEpoch();
-
-  /**
-   * True if this [Date] is set to UTC time.
-   */
-  bool get isUtc();
-
-  /**
-   * Returns a human readable string for this instance.
-   * The returned string is constructed for the time zone of this instance.
-   */
-  String toString();
-
-  /**
-   * Returns a new [Date] with the [duration] added to this instance.
-   */
-  Date add(Duration duration);
-
-  /**
-   * Returns a new [Date] with the [duration] subtracted from this instance.
-   */
-  Date subtract(Duration duration);
-
-  /**
-   * Returns a [Duration] with the difference of [:this:] and [other].
-   */
-  Duration difference(Date other);
-}