Re-landing http://codereview.chromium.org/7014019.

Adding DateTimeFormat class to i18n API with following methods:

- format
- getWeekdays
- getMonths
- get Eras
- getAmPm

Difference from the reverted revision:

Removed all references to v8/src, like ASSERT_EQ.

All #includes have full path to include/v8.h or extension headers.

TEST=Visit i18n.kaziprst.org/datetimeformat.html
Review URL: http://codereview.chromium.org/7105002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8151 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/extensions/experimental/datetime-format.cc

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "src/extensions/experimental/datetime-format.h"
+
+#include <string.h>
+
+#include "src/extensions/experimental/i18n-utils.h"
+#include "unicode/dtfmtsym.h"
+#include "unicode/dtptngen.h"
+#include "unicode/locid.h"
+#include "unicode/smpdtfmt.h"
+
+namespace v8 {
+namespace internal {
+
+v8::Persistent<v8::FunctionTemplate> DateTimeFormat::datetime_format_template_;
+
+static icu::DateFormat* CreateDateTimeFormat(v8::Handle<v8::String>,
+                                             v8::Handle<v8::Object>);
+static v8::Handle<v8::Value> GetSymbols(
+    const v8::Arguments&,
+    const icu::UnicodeString*, int32_t,
+    const icu::UnicodeString*, int32_t,
+    const icu::UnicodeString*, int32_t);
+static v8::Handle<v8::Value> ThrowUnexpectedObjectError();
+static icu::DateFormat::EStyle GetDateTimeStyle(const icu::UnicodeString&);
+
+icu::SimpleDateFormat* DateTimeFormat::UnpackDateTimeFormat(
+    v8::Handle<v8::Object> obj) {
+  if (datetime_format_template_->HasInstance(obj)) {
+    return static_cast<icu::SimpleDateFormat*>(
+        obj->GetPointerFromInternalField(0));
+  }
+
+  return NULL;
+}
+
+void DateTimeFormat::DeleteDateTimeFormat(v8::Persistent<v8::Value> object,
+                                          void* param) {
+  v8::Persistent<v8::Object> persistent_object =
+      v8::Persistent<v8::Object>::Cast(object);
+
+  // First delete the hidden C++ object.
+  // Unpacking should never return NULL here. That would only happen if
+  // this method is used as the weak callback for persistent handles not
+  // pointing to a date time formatter.
+  delete UnpackDateTimeFormat(persistent_object);
+
+  // Then dispose of the persistent handle to JS object.
+  persistent_object.Dispose();
+}
+
+v8::Handle<v8::Value> DateTimeFormat::Format(const v8::Arguments& args) {
+  v8::HandleScope handle_scope;
+
+  double millis = 0.0;
+  if (args.Length() != 1 || !args[0]->IsDate()) {
+    // Create a new date.
+    v8::TryCatch try_catch;
+    v8::Local<v8::Script> date_script =
+        v8::Script::Compile(v8::String::New("eval('new Date()')"));
+    millis = date_script->Run()->NumberValue();
+    if (try_catch.HasCaught()) {
+      return try_catch.ReThrow();
+    }
+  } else {
+    millis = v8::Date::Cast(*args[0])->NumberValue();
+  }
+
+  icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
+  if (!date_format) {
+    return ThrowUnexpectedObjectError();
+  }
+
+  icu::UnicodeString result;
+  date_format->format(millis, result);
+
+  return v8::String::New(
+      reinterpret_cast<const uint16_t*>(result.getBuffer()), result.length());
+}
+
+v8::Handle<v8::Value> DateTimeFormat::GetMonths(const v8::Arguments& args) {
+  icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
+  if (!date_format) {
+    return ThrowUnexpectedObjectError();
+  }
+
+  const icu::DateFormatSymbols* symbols = date_format->getDateFormatSymbols();
+
+  int32_t narrow_count;
+  const icu::UnicodeString* narrow = symbols->getMonths(
+      narrow_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::NARROW);
+  int32_t abbrev_count;
+  const icu::UnicodeString* abbrev = symbols->getMonths(
+      abbrev_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::ABBREVIATED);
+  int32_t wide_count;
+  const icu::UnicodeString* wide = symbols->getMonths(
+      wide_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::WIDE);
+
+  return GetSymbols(
+      args, narrow, narrow_count, abbrev, abbrev_count, wide, wide_count);
+}
+
+v8::Handle<v8::Value> DateTimeFormat::GetWeekdays(const v8::Arguments& args) {
+  icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
+  if (!date_format) {
+    ThrowUnexpectedObjectError();
+  }
+
+  const icu::DateFormatSymbols* symbols = date_format->getDateFormatSymbols();
+
+  int32_t narrow_count;
+  const icu::UnicodeString* narrow = symbols->getWeekdays(
+      narrow_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::NARROW);
+  int32_t abbrev_count;
+  const icu::UnicodeString* abbrev = symbols->getWeekdays(
+      abbrev_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::ABBREVIATED);
+  int32_t wide_count;
+  const icu::UnicodeString* wide = symbols->getWeekdays(
+      wide_count,
+      icu::DateFormatSymbols::STANDALONE,
+      icu::DateFormatSymbols::WIDE);
+
+  // getXXXWeekdays always returns 8 elements - ICU stable API.
+  // We can't use ASSERT_EQ(8, narrow_count) because ASSERT is internal to v8.
+  if (narrow_count != 8 || abbrev_count != 8 || wide_count != 8) {
+    return v8::ThrowException(v8::Exception::Error(
+        v8::String::New("Failed to get weekday information.")));
+  }
+
+  // ICU documentation says we should ignore element 0 of the returned array.
+  return GetSymbols(args, narrow + 1, narrow_count - 1, abbrev + 1,
+                    abbrev_count -1 , wide + 1, wide_count - 1);
+}
+
+v8::Handle<v8::Value> DateTimeFormat::GetEras(const v8::Arguments& args) {
+  icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
+  if (!date_format) {
+    return ThrowUnexpectedObjectError();
+  }
+
+  const icu::DateFormatSymbols* symbols = date_format->getDateFormatSymbols();
+
+  int32_t narrow_count;
+  const icu::UnicodeString* narrow = symbols->getNarrowEras(narrow_count);
+  int32_t abbrev_count;
+  const icu::UnicodeString* abbrev = symbols->getEras(abbrev_count);
+  int32_t wide_count;
+  const icu::UnicodeString* wide = symbols->getEraNames(wide_count);
+
+  return GetSymbols(
+      args, narrow, narrow_count, abbrev, abbrev_count, wide, wide_count);
+}
+
+v8::Handle<v8::Value> DateTimeFormat::GetAmPm(const v8::Arguments& args) {
+  icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
+  if (!date_format) {
+    return ThrowUnexpectedObjectError();
+  }
+
+  const icu::DateFormatSymbols* symbols = date_format->getDateFormatSymbols();
+
+  // In this case narrow == abbreviated == wide
+  int32_t count;
+  const icu::UnicodeString* wide = symbols->getAmPmStrings(count);
+
+  return GetSymbols(args, wide, count, wide, count, wide, count);
+}
+
+v8::Handle<v8::Value> DateTimeFormat::JSDateTimeFormat(
+    const v8::Arguments& args) {
+  v8::HandleScope handle_scope;
+
+  if (args.Length() != 2 || !args[0]->IsString() || !args[1]->IsObject()) {
+    return v8::ThrowException(v8::Exception::SyntaxError(
+        v8::String::New("Locale and date/time options are required.")));
+  }
+
+  icu::SimpleDateFormat* date_format = static_cast<icu::SimpleDateFormat*>(
+      CreateDateTimeFormat(args[0]->ToString(), args[1]->ToObject()));
+
+  if (datetime_format_template_.IsEmpty()) {
+    v8::Local<v8::FunctionTemplate> raw_template(v8::FunctionTemplate::New());
+
+    raw_template->SetClassName(v8::String::New("v8Locale.DateTimeFormat"));
+
+    // Define internal field count on instance template.
+    v8::Local<v8::ObjectTemplate> object_template =
+        raw_template->InstanceTemplate();
+
+    // Set aside internal field for icu date time formatter.
+    object_template->SetInternalFieldCount(1);
+
+    // Define all of the prototype methods on prototype template.
+    v8::Local<v8::ObjectTemplate> proto = raw_template->PrototypeTemplate();
+    proto->Set(v8::String::New("format"),
+               v8::FunctionTemplate::New(Format));
+    proto->Set(v8::String::New("getMonths"),
+               v8::FunctionTemplate::New(GetMonths));
+    proto->Set(v8::String::New("getWeekdays"),
+               v8::FunctionTemplate::New(GetWeekdays));
+    proto->Set(v8::String::New("getEras"),
+               v8::FunctionTemplate::New(GetEras));
+    proto->Set(v8::String::New("getAmPm"),
+               v8::FunctionTemplate::New(GetAmPm));
+
+    datetime_format_template_ =
+        v8::Persistent<v8::FunctionTemplate>::New(raw_template);
+  }
+
+  // Create an empty object wrapper.
+  v8::Local<v8::Object> local_object =
+      datetime_format_template_->GetFunction()->NewInstance();
+  v8::Persistent<v8::Object> wrapper =
+      v8::Persistent<v8::Object>::New(local_object);
+
+  // Set date time formatter as internal field of the resulting JS object.
+  wrapper->SetPointerInInternalField(0, date_format);
+
+  // Set resolved pattern in options.pattern.
+  icu::UnicodeString pattern;
+  date_format->toPattern(pattern);
+  v8::Local<v8::Object> options = v8::Object::New();
+  options->Set(v8::String::New("pattern"),
+               v8::String::New(reinterpret_cast<const uint16_t*>(
+                   pattern.getBuffer()), pattern.length()));
+  wrapper->Set(v8::String::New("options"), options);
+
+  // Make object handle weak so we can delete iterator once GC kicks in.
+  wrapper.MakeWeak(NULL, DeleteDateTimeFormat);
+
+  return wrapper;
+}
+
+// Returns SimpleDateFormat.
+static icu::DateFormat* CreateDateTimeFormat(
+    v8::Handle<v8::String> locale, v8::Handle<v8::Object> settings) {
+  v8::HandleScope handle_scope;
+
+  v8::String::AsciiValue ascii_locale(locale);
+  icu::Locale icu_locale(*ascii_locale);
+
+  // Make formatter from skeleton.
+  icu::SimpleDateFormat* date_format = NULL;
+  UErrorCode status = U_ZERO_ERROR;
+  icu::UnicodeString skeleton;
+  if (I18NUtils::ExtractStringSetting(settings, "skeleton", &skeleton)) {
+    v8::Local<icu::DateTimePatternGenerator> generator(
+        icu::DateTimePatternGenerator::createInstance(icu_locale, status));
+    icu::UnicodeString pattern =
+        generator->getBestPattern(skeleton, status);
+
+    date_format = new icu::SimpleDateFormat(pattern, icu_locale, status);
+    if (U_SUCCESS(status)) {
+      return date_format;
+    } else {
+      delete date_format;
+    }
+  }
+
+  // Extract date type and time type from settings.
+  icu::UnicodeString date_type;
+  icu::DateFormat::EStyle date_style = icu::DateFormat::kNone;
+  if (I18NUtils::ExtractStringSetting(settings, "dateType", &date_type)) {
+    date_style = GetDateTimeStyle(date_type);
+  }
+
+  icu::UnicodeString time_type;
+  icu::DateFormat::EStyle time_style = icu::DateFormat::kNone;
+  if (I18NUtils::ExtractStringSetting(settings, "timeType", &time_type)) {
+    time_style = GetDateTimeStyle(time_type);
+  }
+
+  // Try all combinations of date/time types.
+  if (date_style == icu::DateFormat::kNone &&
+      time_style == icu::DateFormat::kNone) {
+    // Return default short date, short
+    return icu::DateFormat::createDateTimeInstance(
+        icu::DateFormat::kShort, icu::DateFormat::kShort, icu_locale);
+  } else if (date_style != icu::DateFormat::kNone &&
+             time_style != icu::DateFormat::kNone) {
+    return icu::DateFormat::createDateTimeInstance(
+        date_style, time_style, icu_locale);
+  } else if (date_style != icu::DateFormat::kNone) {
+    return icu::DateFormat::createDateInstance(date_style, icu_locale);
+  } else {
+    // time_style != icu::DateFormat::kNone
+    return icu::DateFormat::createTimeInstance(time_style, icu_locale);
+  }
+}
+
+// Creates a v8::Array of narrow, abbrev or wide symbols.
+static v8::Handle<v8::Value> GetSymbols(const v8::Arguments& args,
+                                        const icu::UnicodeString* narrow,
+                                        int32_t narrow_count,
+                                        const icu::UnicodeString* abbrev,
+                                        int32_t abbrev_count,
+                                        const icu::UnicodeString* wide,
+                                        int32_t wide_count) {
+  v8::HandleScope handle_scope;
+
+  // Make wide width default.
+  const icu::UnicodeString* result = wide;
+  int32_t count = wide_count;
+
+  if (args.Length() == 1 && args[0]->IsString()) {
+    v8::String::AsciiValue ascii_value(args[0]);
+    if (strcmp(*ascii_value, "abbreviated") == 0) {
+      result = abbrev;
+      count = abbrev_count;
+    } else if (strcmp(*ascii_value, "narrow") == 0) {
+      result = narrow;
+      count = narrow_count;
+    }
+  }
+
+  v8::Handle<v8::Array> symbols = v8::Array::New();
+  for (int32_t i = 0; i < count; ++i) {
+    symbols->Set(i, v8::String::New(
+        reinterpret_cast<const uint16_t*>(result[i].getBuffer()),
+        result[i].length()));
+  }
+
+  return handle_scope.Close(symbols);
+}
+
+// Throws a JavaScript exception.
+static v8::Handle<v8::Value> ThrowUnexpectedObjectError() {
+  // Returns undefined, and schedules an exception to be thrown.
+  return v8::ThrowException(v8::Exception::Error(
+      v8::String::New("DateTimeFormat method called on an object "
+                      "that is not a DateTimeFormat.")));
+}
+
+// Returns icu date/time style.
+static icu::DateFormat::EStyle GetDateTimeStyle(
+    const icu::UnicodeString& type) {
+  if (type == UNICODE_STRING_SIMPLE("medium")) {
+    return icu::DateFormat::kMedium;
+  } else if (type == UNICODE_STRING_SIMPLE("long")) {
+    return icu::DateFormat::kLong;
+  } else if (type == UNICODE_STRING_SIMPLE("full")) {
+    return icu::DateFormat::kFull;
+  }
+
+  return icu::DateFormat::kShort;
+}
+
+} }  // namespace v8::internal

src/extensions/experimental/datetime-format.h

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_EXTENSIONS_EXPERIMENTAL_DATETIME_FORMAT_H_
+#define V8_EXTENSIONS_EXPERIMENTAL_DATETIME_FORMAT_H_
+
+#include "include/v8.h"
+
+#include "unicode/uversion.h"
+
+namespace U_ICU_NAMESPACE {
+class SimpleDateFormat;
+}
+
+namespace v8 {
+namespace internal {
+
+class DateTimeFormat {
+ public:
+  static v8::Handle<v8::Value> JSDateTimeFormat(const v8::Arguments& args);
+
+  // Helper methods for various bindings.
+
+  // Unpacks date format object from corresponding JavaScript object.
+  static icu::SimpleDateFormat* UnpackDateTimeFormat(
+      v8::Handle<v8::Object> obj);
+
+  // Release memory we allocated for the DateFormat once the JS object that
+  // holds the pointer gets garbage collected.
+  static void DeleteDateTimeFormat(v8::Persistent<v8::Value> object,
+                                   void* param);
+
+  // Formats date and returns corresponding string.
+  static v8::Handle<v8::Value> Format(const v8::Arguments& args);
+
+  // All date time symbol methods below return stand-alone names in
+  // either narrow, abbreviated or wide width.
+
+  // Get list of months.
+  static v8::Handle<v8::Value> GetMonths(const v8::Arguments& args);
+
+  // Get list of weekdays.
+  static v8::Handle<v8::Value> GetWeekdays(const v8::Arguments& args);
+
+  // Get list of eras.
+  static v8::Handle<v8::Value> GetEras(const v8::Arguments& args);
+
+  // Get list of day periods.
+  static v8::Handle<v8::Value> GetAmPm(const v8::Arguments& args);
+
+ private:
+  DateTimeFormat();
+
+  static v8::Persistent<v8::FunctionTemplate> datetime_format_template_;
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_EXTENSIONS_EXPERIMENTAL_DATETIME_FORMAT_H_

src/extensions/experimental/experimental.gyp

@@ -41,6 +41,8 @@
         'break-iterator.h',
         'collator.cc',
         'collator.h',
+        'datetime-format.cc',
+        'datetime-format.h',
         'i18n-extension.cc',
         'i18n-extension.h',
         'i18n-locale.cc',

src/extensions/experimental/i18n-extension.cc

@@ -29,6 +29,7 @@
 
 #include "src/extensions/experimental/break-iterator.h"
 #include "src/extensions/experimental/collator.h"
+#include "src/extensions/experimental/datetime-format.h"
 #include "src/extensions/experimental/i18n-locale.h"
 #include "src/extensions/experimental/i18n-natives.h"
 
@@ -49,6 +50,8 @@ v8::Handle<v8::FunctionTemplate> I18NExtension::GetNativeFunction(
     return v8::FunctionTemplate::New(BreakIterator::JSBreakIterator);
   } else if (name->Equals(v8::String::New("NativeJSCollator"))) {
     return v8::FunctionTemplate::New(Collator::JSCollator);
+  } else if (name->Equals(v8::String::New("NativeJSDateTimeFormat"))) {
+    return v8::FunctionTemplate::New(DateTimeFormat::JSDateTimeFormat);
   }
 
   return v8::Handle<v8::FunctionTemplate>();

src/extensions/experimental/i18n-utils.cc

@@ -29,6 +29,8 @@
 
 #include <string.h>
 
+#include "unicode/unistr.h"
+
 namespace v8 {
 namespace internal {
 
@@ -40,4 +42,27 @@ void I18NUtils::StrNCopy(char* dest, int length, const char* src) {
   dest[length - 1] = '\0';
 }
 
+// static
+bool I18NUtils::ExtractStringSetting(const v8::Handle<v8::Object>& settings,
+                                     const char* setting,
+                                     icu::UnicodeString* result) {
+  if (!setting || !result) return false;
+
+  v8::HandleScope handle_scope;
+  v8::TryCatch try_catch;
+  v8::Handle<v8::Value> value = settings->Get(v8::String::New(setting));
+  if (try_catch.HasCaught()) {
+    return false;
+  }
+  // No need to check if |value| is empty because it's taken care of
+  // by TryCatch above.
+  if (!value->IsUndefined() && !value->IsNull() && value->IsString()) {
+    v8::String::Utf8Value utf8_value(value);
+    if (*utf8_value == NULL) return false;
+    result->setTo(icu::UnicodeString::fromUTF8(*utf8_value));
+    return true;
+  }
+  return false;
+}
+
 } }  // namespace v8::internal

src/extensions/experimental/i18n-utils.h

@@ -28,6 +28,14 @@
 #ifndef V8_EXTENSIONS_EXPERIMENTAL_I18N_UTILS_H_
 #define V8_EXTENSIONS_EXPERIMENTAL_I18N_UTILS_H_
 
+#include "include/v8.h"
+
+#include "unicode/uversion.h"
+
+namespace U_ICU_NAMESPACE {
+class UnicodeString;
+}
+
 namespace v8 {
 namespace internal {
 
@@ -37,9 +45,14 @@ class I18NUtils {
   // (length - 1) bytes.
   // We can't use snprintf since it's not supported on all relevant platforms.
   // We can't use OS::SNPrintF, it's only for internal code.
-  // TODO(cira): Find a way to use OS::SNPrintF instead.
   static void StrNCopy(char* dest, int length, const char* src);
 
+  // Extract a string setting named in |settings| and set it to |result|.
+  // Return true if it's specified. Otherwise, return false.
+  static bool ExtractStringSetting(const v8::Handle<v8::Object>& settings,
+                                   const char* setting,
+                                   icu::UnicodeString* result);
+
  private:
   I18NUtils() {}
 };

src/extensions/experimental/i18n.js

@@ -45,11 +45,11 @@ v8Locale = function(settings) {
   }
 
   var properties = NativeJSLocale(
-      v8Locale.createSettingsOrDefault_(settings, {'localeID': 'root'}));
+      v8Locale.__createSettingsOrDefault(settings, {'localeID': 'root'}));
 
   // Keep the resolved ICU locale ID around to avoid resolving localeID to
   // ICU locale ID every time BreakIterator, Collator and so forth are called.
-  this.__icuLocaleID__ = properties.icuLocaleID;
+  this.__icuLocaleID = properties.icuLocaleID;
   this.options = {'localeID': properties.localeID,
                   'regionID': properties.regionID};
 };
@@ -61,7 +61,7 @@ v8Locale = function(settings) {
  */
 v8Locale.prototype.derive = function(settings) {
   return new v8Locale(
-      v8Locale.createSettingsOrDefault_(settings, this.options));
+      v8Locale.__createSettingsOrDefault(settings, this.options));
 };
 
 /**
@@ -74,14 +74,15 @@ v8Locale.prototype.derive = function(settings) {
  *   - word
  *   - sentence
  *   - line
+ * @private
  * @constructor
  */
 v8Locale.v8BreakIterator = function(locale, type) {
   native function NativeJSBreakIterator();
 
-  locale = v8Locale.createLocaleOrDefault_(locale);
+  locale = v8Locale.__createLocaleOrDefault(locale);
   // BCP47 ID would work in this case, but we use ICU locale for consistency.
-  var iterator = NativeJSBreakIterator(locale.__icuLocaleID__, type);
+  var iterator = NativeJSBreakIterator(locale.__icuLocaleID, type);
   iterator.type = type;
   return iterator;
 };
@@ -117,26 +118,110 @@ v8Locale.prototype.v8CreateBreakIterator = function(type) {
  *   - ignoreCase
  *   - ignoreAccents
  *   - numeric
+ * @private
  * @constructor
  */
 v8Locale.Collator = function(locale, settings) {
   native function NativeJSCollator();
 
-  locale = v8Locale.createLocaleOrDefault_(locale);
+  locale = v8Locale.__createLocaleOrDefault(locale);
   var collator = NativeJSCollator(
-      locale.__icuLocaleID__, v8Locale.createSettingsOrDefault_(settings, {}));
+      locale.__icuLocaleID, v8Locale.__createSettingsOrDefault(settings, {}));
   return collator;
 };
 
 /**
  * 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.
+ * Constructor is not part of public API.
+ * @param {Object} locale - locale object to pass to formatter.
+ * @param {Object} settings - formatting flags:
+ *   - skeleton
+ *   - dateType
+ *   - timeType
+ *   - calendar
+ * @private
+ * @constructor
+ */
+v8Locale.__DateTimeFormat = function(locale, settings) {
+  native function NativeJSDateTimeFormat();
+
+  settings = v8Locale.__createSettingsOrDefault(settings, {});
+
+  var cleanSettings = {};
+  if (settings.hasOwnProperty('skeleton')) {
+    cleanSettings['skeleton'] = settings['skeleton'];
+  } else {
+    cleanSettings = {};
+    if (settings.hasOwnProperty('dateType')) {
+      var dt = settings['dateType'];
+      if (!/^short|medium|long|full$/.test(dt)) dt = 'short';
+      cleanSettings['dateType'] = dt;
+    }
+
+    if (settings.hasOwnProperty('timeType')) {
+      var tt = settings['timeType'];
+      if (!/^short|medium|long|full$/.test(tt)) tt = 'short';
+      cleanSettings['timeType'] = tt;
+    }
+  }
+
+  // Default is to show short date and time.
+  if (!cleanSettings.hasOwnProperty('skeleton') &&
+      !cleanSettings.hasOwnProperty('dateType') &&
+      !cleanSettings.hasOwnProperty('timeType')) {
+    cleanSettings = {'dateType': 'short',
+                     'timeType': 'short'};
+  }
+
+  locale = v8Locale.__createLocaleOrDefault(locale);
+  var formatter = NativeJSDateTimeFormat(locale.__icuLocaleID, cleanSettings);
+
+  // NativeJSDateTimeFormat creates formatter.options for us, we just need
+  // to append actual settings to it.
+  for (key in cleanSettings) {
+    formatter.options[key] = cleanSettings[key];
+  }
+
+  /**
+   * 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.
+   * @public
+   */
+  formatter.derive = function(overrideSettings) {
+    // To remove a setting user can specify undefined as its value. We'll remove
+    // it from the map in that case.
+    for (var prop in overrideSettings) {
+      if (settings.hasOwnProperty(prop) && !overrideSettings[prop]) {
+        delete settings[prop];
+      }
+    }
+    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.
@@ -145,8 +230,9 @@ v8Locale.prototype.createCollator = function(settings) {
  * @param {!Object} settings - user provided settings.
  * @param {!Object} defaults - default values for this type of settings.
  * @returns {Object} - valid settings object.
+ * @private
  */
-v8Locale.createSettingsOrDefault_ = function(settings, defaults) {
+v8Locale.__createSettingsOrDefault = function(settings, defaults) {
   if (!settings || typeof(settings) !== 'object' ) {
     return defaults;
   }
@@ -155,11 +241,17 @@ v8Locale.createSettingsOrDefault_ = function(settings, defaults) {
       settings[key] = defaults[key];
     }
   }
-  // Clean up values, like trimming whitespace.
+  // Clean up settings.
   for (var key in settings) {
+    // Trim whitespace.
     if (typeof(settings[key]) === "string") {
       settings[key] = settings[key].trim();
     }
+    // Remove all properties that are set to undefined/null. This allows
+    // derive method to remove a setting we don't need anymore.
+    if (!settings[key]) {
+      delete settings[key];
+    }
   }
 
   return settings;
@@ -170,8 +262,9 @@ v8Locale.createSettingsOrDefault_ = function(settings, defaults) {
  * we create default locale and return it.
  * @param {!Object} locale - user provided locale.
  * @returns {Object} - v8Locale object.
+ * @private
  */
-v8Locale.createLocaleOrDefault_ = function(locale) {
+v8Locale.__createLocaleOrDefault = function(locale) {
   if (!locale || !(locale instanceof v8Locale)) {
     return new v8Locale();
   } else {