Adding DateTimeFormat class to i18n API.

src/extensions/experimental/i18n.js

Index: src/extensions/experimental/i18n.js
===================================================================
--- src/extensions/experimental/i18n.js	(revision 7878)
+++ src/extensions/experimental/i18n.js	(working copy)
@@ -131,13 +131,88 @@
 /**
  * Creates new Collator based on current locale.
  * @param {Object} - collation flags. See constructor.
- * @returns {Object} - new v8BreakIterator object.
+ * @returns {Object} - new Collator object.
  */
 v8Locale.prototype.createCollator = function(settings) {
   return new v8Locale.Collator(this, settings);
 };
 
 /**
+ * DateTimeFormat class implements locale-aware date and time formatting.
+ * @param {Object} locale - locale object to pass to formatter.
+ * @param {Object} settings - formatting flags:
+ *   - skeleton
+ *   - dateType
+ *   - timeType
+ *   - calendar
+ * @constructor
+ */
+v8Locale.DateTimeFormat = function(locale, settings) {
+  native function NativeJSDateTimeFormat();
+
+  settings = v8Locale.createSettingsOrDefault_(settings, {});
+
+  var shortDate = 'yMMdd';

[jungshik at Google, 2011/05/13 23:37:53]

Hmm... this is problematic in some locales. In Korean, SHORT date format does
not use zero-padding, but there is a pattern for MMdd in case zero-padded month
number and day number are desired. If the skeleton has 'MMdd', the pattern
picked up will do zero-padding, which is not actual 'Short' format for Korean in
CLDR. 

Perhaps, 'yMd' works better for some locales, but it may break other locales in
the opposite direction. 

I guess the best is to use real SHORT date style directly. It's more involved,
but I don't see any work around that.

[Nebojša Ćirić, 2011/05/17 20:40:37]

Done.

+  var longDate = 'EEEEyMMMdd';
+  var shortTime = 'jm';
+  var mediumTime = 'jms';
+  var skeleton = shortDate + shortTime;
+  if (settings.hasOwnProperty('skeleton')) {
+    skeleton = settings['skeleton'];
+  } else if (settings.hasOwnProperty('dateType') &&
+             settings.hasOwnProperty('timeType')) {

[jungshik at Google, 2011/05/13 23:37:53]

After our discussion, this point became unapplicable because you're gonna change
datetype/timetype handling per our discussion/the comment above. Just for the
record, I'm leaving it alone (in case we change our mind again :-))

How about this?

var skeleton = "";

if (has skeleton) {
   skeleton = settings...
} else {
  if (has ('dateType')) {
    var dt = settings['dateType'];
    if (dt === 'short') 
      skeleton = shortDate;
    else if (dt === 'medium')
      skeleton = mediumDate;
  }
  if (has timeType) {
     var tt = ....
     if (tt is short)
        skeleton += shortTime;
     ....
  }

  if (skeleton == "") 
     skeleton = shortTime + shortDate
}

[Nebojša Ćirić, 2011/05/17 20:40:37]

Done.

+    var dt = settings['dateType'];
+    var tt = settings['timeType'];
+    if (dt === 'short' && tt === 'short') {
+      skeleton = shortDate + shortTime;
+    } else if (dt === 'short' && tt === 'medium') {
+      skeleton = shortDate + mediumTime;
+    } else if (dt === 'long' && tt === 'short') {
+      skeleton = longDate + shortTime;
+    } else if (dt === 'long' && tt === 'medium') {
+      skeleton = longDate + mediumTime;
+    }
+  } else if (settings.hasOwnProperty('dateType')) {
+    if (settings['dateType'] === 'short') {
+      skeleton = shortDate;
+    } else if (settings['dateType'] === 'long') {
+      skeleton = longDate;
+    }
+  } else if (settings.hasOwnProperty('timeType')) {
+    if (settings['timeType'] === 'short') {
+      skeleton = shortTime;
+    } else if (settings['timeType'] === 'medium') {
+      skeleton = mediumTime;
+    }
+  }
+
+  locale = v8Locale.createLocaleOrDefault_(locale);
+  var formatter = NativeJSDateTimeFormat(locale.__icuLocaleID__, skeleton);
+
+  /**
+   * Clones existing date time format with possible overrides for some
+   * of the options.
+   * @param {!Object} overrideSettings - overrides for current format settings.
+   * @returns {Object} - new DateTimeFormat object.
+   */
+  formatter.derive = function(overrideSettings) {
+    return new v8Locale.DateTimeFormat(
+        locale, v8Locale.createSettingsOrDefault_(overrideSettings, settings));
+  };
+
+  return formatter;
+};
+
+/**
+ * Creates new DateTimeFormat based on current locale.
+ * @param {Object} - formatting flags. See constructor.
+ * @returns {Object} - new DateTimeFormat object.
+ */
+v8Locale.prototype.createDateTimeFormat = function(settings) {
+  return new v8Locale.DateTimeFormat(this, settings);
+};
+
+/**
  * Merges user settings and defaults.
  * Settings that are not of object type are rejected.
  * Actual property values are not validated, but whitespace is trimmed if they