Add toIso8601String to DateTime.

sdk/lib/core/date_time.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.
 
 part of dart.core;
 
 /**
  * An instant in time, such as July 20, 1969, 8:18pm GMT.
  *
  * Create a DateTime object by using one of the constructors
@@ skipping 379 matching lines @@
    *
    *     new DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch,
    *                                             isUtc: true)
    */
   DateTime toUtc() {
     if (isUtc) return this;
     return new DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch,
                                                    isUtc: true);
   }
 
+  static String _fourDigits(int n) {
+    int absN = n.abs();
+    String sign = n < 0 ? "-" : "";
+    if (absN >= 1000) return "$n";
+    if (absN >= 100) return "${sign}0$absN";
+    if (absN >= 10) return "${sign}00$absN";
+    return "${sign}000$absN";
+  }
+
+  static String _threeDigits(int n) {
+    if (n >= 100) return "${n}";
+    if (n >= 10) return "0${n}";
+    return "00${n}";
+  }
+
+  static String _twoDigits(int n) {
+    if (n >= 10) return "${n}";
+    return "0${n}";
+  }
+
   /**
    * Returns a human-readable string for this instance.
    *
    * The returned string is constructed for the time zone of this instance.
    * The `toString()` method provides a simply formatted string.
    * It does not support internationalized strings.
    * Use the [intl](http://pub.dartlang.org/packages/intl) package
    * at the pub shared packages repo.
    */
   String toString() {
-    String fourDigits(int n) {
-      int absN = n.abs();
-      String sign = n < 0 ? "-" : "";
-      if (absN >= 1000) return "$n";
-      if (absN >= 100) return "${sign}0$absN";
-      if (absN >= 10) return "${sign}00$absN";
-      return "${sign}000$absN";
-    }
-
-    String threeDigits(int n) {
-      if (n >= 100) return "${n}";
-      if (n >= 10) return "0${n}";
-      return "00${n}";
-    }
-
-    String twoDigits(int n) {
-      if (n >= 10) return "${n}";
-      return "0${n}";
-    }
-
-    String y = fourDigits(year);
-    String m = twoDigits(month);
-    String d = twoDigits(day);
-    String h = twoDigits(hour);
-    String min = twoDigits(minute);
-    String sec = twoDigits(second);
-    String ms = threeDigits(millisecond);
+    String y = _fourDigits(year);
+    String m = _twoDigits(month);
+    String d = _twoDigits(day);
+    String h = _twoDigits(hour);
+    String min = _twoDigits(minute);
+    String sec = _twoDigits(second);
+    String ms = _threeDigits(millisecond);
     if (isUtc) {
       return "$y-$m-$d $h:$min:$sec.${ms}Z";
     } else {
       return "$y-$m-$d $h:$min:$sec.$ms";
     }
   }
 
   /**
+   * Returns an ISO-8601 full-precision extended format representation.
+   *
+   * The format is "YYYY-MM-DDTHH:mm:ss.sssZ" for UTC time, and
+   * "YYYY-MM-DDTHH:mm:ss.sss" (no trailing "Z") for local/non-UTC time.
+   */
+  String toIso8601String() {
+    String y = _fourDigits(year);
+    String m = _twoDigits(month);
+    String d = _twoDigits(day);
+    String h = _twoDigits(hour);
+    String min = _twoDigits(minute);
+    String sec = _twoDigits(second);
+    String ms = _threeDigits(millisecond);
+    if (isUtc) {
+      return "$y-$m-${d}T$h:$min:$sec.${ms}Z";
+    } else {
+      return "$y-$m-${d}T$h:$min:$sec.$ms";
+    }
+  }
+
+  /**
    * Returns a new [DateTime] instance with [duration] added to [this].
    *
    *     DateTime today = new DateTime.now();
    *     DateTime sixtyDaysFromNow = today.add(new Duration(days: 60));
    */
-
   DateTime add(Duration duration) {
     int ms = millisecondsSinceEpoch;
     return new DateTime.fromMillisecondsSinceEpoch(
         ms + duration.inMilliseconds, isUtc: isUtc);
   }
 
   /**
    * Returns a new [DateTime] instance with [duration] subtracted from [this].
    *
    *     DateTime today = new DateTime.now();
@@ skipping 115 matching lines @@
    * In accordance with ISO 8601
    * a week starts with Monday, which has the value 1.
    *
    *     DateTime moonLanding = DateTime.parse("1969-07-20 20:18:00");
    *     assert(moonLanding.weekday == 7);
    *     assert(moonLanding.weekday == DateTime.SUNDAY);
    *
    */
   external int get weekday;
 }