Change v8Locale to match proposal - constructor is different and I've added

src/extensions/experimental/language-matcher.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.
+
+// TODO(cira): Remove LanguageMatcher from v8 when ICU implements
+// language matching API.
+
+#include "language-matcher.h"
+
+#include "platform.h"
+#include "unicode/datefmt.h"  // For getAvailableLocales
+#include "unicode/locid.h"
+#include "unicode/uloc.h"
+#include "utils.h"
+
+namespace v8 {
+namespace internal {
+
+const unsigned int LanguageMatcher::kLanguageWeight = 75;
+const unsigned int LanguageMatcher::kScriptWeight = 20;
+const unsigned int LanguageMatcher::kRegionWeight = 5;
+const unsigned int LanguageMatcher::kThreshold = 50;
+const unsigned int LanguageMatcher::kPositionBonus = 1;
+const char* const LanguageMatcher::kDefaultLocale = "root";
+
+static const char* GetLanguageException(const char*);
+static void BCP47ToICUFormat(v8::Handle<v8::String>, char*);
+static int CompareLocaleSubtags(const char*, const char*);
+static bool BuildLocaleName(const char*, const char*, LocaleIDMatch*);
+
+LocaleIDMatch::LocaleIDMatch()
+    : score(-1) {
+  OS::SNPrintF(Vector<char>(bcp47_id, ULOC_FULLNAME_CAPACITY),
+               "%s", LanguageMatcher::kDefaultLocale);
+  OS::SNPrintF(Vector<char>(icu_id, ULOC_FULLNAME_CAPACITY),
+               "%s", LanguageMatcher::kDefaultLocale);
+}
+
+LocaleIDMatch& LocaleIDMatch::operator=(const LocaleIDMatch& rhs) {
+  OS::SNPrintF(Vector<char>(this->bcp47_id, ULOC_FULLNAME_CAPACITY),
+               "%s", rhs.bcp47_id);
+  OS::SNPrintF(Vector<char>(this->icu_id, ULOC_FULLNAME_CAPACITY),
+               "%s", rhs.icu_id);
+  this->score = rhs.score;
+
+  return *this;
+}
+
+// static
+void LanguageMatcher::GetBestMatchForPriorityList(
+    v8::Handle<v8::Array> locales, LocaleIDMatch* result) {
+  v8::HandleScope handle_scope;
+
+  unsigned int position_bonus = locales->Length() * kPositionBonus;
+
+  int max_score = 0;
+  LocaleIDMatch match;
+  for (unsigned int i = 0; i < locales->Length(); ++i) {
+    position_bonus -= kPositionBonus;
+
+    v8::TryCatch try_catch;
+    v8::Local<v8::Value> locale_id = locales->Get(v8::Integer::New(i));
+
+    // Return default if exception is raised when reading parameter.
+    if (try_catch.HasCaught()) break;
+
+    // JavaScript arrays can be heterogenous so check each item
+    // if it's a string.
+    if (!locale_id->IsString()) continue;
+
+    CompareToSupportedLocaleIDList(locale_id->ToString(), &match);

[jungshik at Google, 2011/05/03 20:04:05]

Perhaps, you can check the return value and skip if it's a failure. 

[Nebojša Ćirić, 2011/05/03 20:39:00]

Done.

+
+    // Skip items under threshold.
+    if (match.score < kThreshold) continue;
+
+    match.score += position_bonus;
+    if (match.score > max_score) {
+      *result = match;
+
+      max_score = match.score;
+    }
+  }
+}
+
+// static
+void LanguageMatcher::GetBestMatchForString(
+    v8::Handle<v8::String> locale, LocaleIDMatch* result) {
+  LocaleIDMatch match;
+  CompareToSupportedLocaleIDList(locale, &match);
+
+  if (match.score >= kThreshold) {
+    *result = match;
+  }

[jungshik at Google, 2011/05/03 20:04:05]

How about this? 

if (CompareToSupportedLocaleIDList(...) && match.score >= kThresold)  ... 

[Nebojša Ćirić, 2011/05/03 20:39:00]

Done.

+}
+
+// static
+void LanguageMatcher::CompareToSupportedLocaleIDList(
+    v8::Handle<v8::String> locale_id, LocaleIDMatch* result) {
+  static int32_t available_count = 0;
+  // Locale::getAvailableLocales would return 100+ locales, with more than 70
+  // with little data. DateFormat variant returns well populated Locales only.

[jungshik at Google, 2011/05/03 20:04:05]

The above comment is specific to Chrome's ICU build.  Perhaps, this is better:

Depending on how ICU data is built, locales returned by
Locale::getAvailableLocale() are not guaranteed to support  DateFormat,
Collation and other services.  We can call getAvailableLocale() of all the
services we want to support and take the intersection of them all, but using
DateFormat::getAvailableLocales() can do in practice. 

[Nebojša Ćirić, 2011/05/03 20:39:00]

Done.

+  // TODO(cira): Maybe make this thread-safe?
+  static const icu::Locale* available_locales =
+      icu::DateFormat::getAvailableLocales(available_count);
+
+  // Skip this locale_id if it's not in ASCII.
+  static LocaleIDMatch default_match;
+  v8::String::AsciiValue is_ascii(locale_id);
+  if (*is_ascii == NULL) {
+    *result = default_match;
+    return;
+  }
+
+  char locale[ULOC_FULLNAME_CAPACITY];
+  BCP47ToICUFormat(locale_id, locale);
+  icu::Locale input_locale(locale);
+
+  // Position of the best match locale in list of available locales.
+  int position = -1;
+  result->score = 0;
+  const char* language = GetLanguageException(input_locale.getLanguage());
+  const char* script = input_locale.getScript();
+  const char* region = input_locale.getCountry();
+  for (int32_t i = 0; i < available_count; ++i) {
+    int current_score = 0;
+    int sign =
+        CompareLocaleSubtags(language, available_locales[i].getLanguage());
+    current_score += sign * kLanguageWeight;
+
+    sign = CompareLocaleSubtags(script, available_locales[i].getScript());
+    current_score += sign * kScriptWeight;
+
+    sign = CompareLocaleSubtags(region, available_locales[i].getCountry());
+    current_score += sign * kRegionWeight;
+
+    if (current_score > result->score) {
+      result->score = current_score;
+      position = i;
+    }
+  }
+
+  if (result->score < kThreshold || position == -1) {
+    *result = default_match;
+    return;
+  }
+
+  BuildLocaleName(available_locales[position].getBaseName(),
+                  input_locale.getName(), result);

[jungshik at Google, 2011/05/03 20:04:05]

If we just want to throw away the return value, there's no point of returning a
boolean, no?  
Perhaps, you can change the above to 

return BuildLocaleName(.....); 

Then, a caller can decide what to do. see above.

[Nebojša Ćirić, 2011/05/03 20:39:00]

Done.

+}
+
+// For some unsupported language subtags it is better to fallback to related
+// language that is supported than to default.
+static const char* GetLanguageException(const char* language) {
+  // Serbo-croatian to Serbian.
+  if (!strcmp(language, "sh")) return "sr";
+
+  // Norweigan to Norweiaan to Norwegian Bokmal.
+  if (!strcmp(language, "no")) return "nb";
+
+  // Moldavian to Romanian.
+  if (!strcmp(language, "mo")) return "ro";
+
+  // Tagalog to Filipino.
+  if (!strcmp(language, "tl")) return "fil";
+
+  return language;
+}
+
+// Converts user input from BCP47 locale id format to ICU compatible format.
+static void BCP47ToICUFormat(v8::Handle<v8::String> locale_id, char* locale) {
+  UErrorCode status = U_ZERO_ERROR;
+  int32_t locale_size = 0;
+  uloc_forLanguageTag(*v8::String::Utf8Value(locale_id), locale,
+                      ULOC_FULLNAME_CAPACITY, &locale_size, &status);
+}
+
+// Compares locale id subtags.
+// Returns 1 for match or -1 for mismatch.
+static int CompareLocaleSubtags(const char* lsubtag, const char* rsubtag) {
+  return strcmp(lsubtag, rsubtag) == 0 ? 1 : -1;
+}
+
+// Builds a BCP47 compliant locale id from base name of matched locale and
+// full user specified locale.
+// Returns false if uloc_toLanguageTag failed to convert locale id.
+// Example:
+//   base_name of matched locale (ICU ID): de_DE
+//   input_locale_name (ICU ID): de_AT@collation=phonebk
+//   result (ICU ID): de_DE@collation=phonebk
+//   result (BCP47 ID): de-DE-u-co-phonebk
+static bool BuildLocaleName(const char* base_name,
+                            const char* input_locale_name,
+                            LocaleIDMatch* result) {
+  // Get extensions (if any) from the original locale.
+  const char* extension = strchr(input_locale_name, ULOC_KEYWORD_SEPARATOR);
+  if (extension != NULL) {
+    OS::SNPrintF(Vector<char>(result->icu_id, ULOC_FULLNAME_CAPACITY),
+                 "%s%s", base_name, extension);
+  } else {
+    OS::SNPrintF(Vector<char>(result->icu_id, ULOC_FULLNAME_CAPACITY),
+                 "%s", base_name);
+  }
+
+  // Convert ICU locale name into BCP47 format.
+  UErrorCode status = U_ZERO_ERROR;
+  uloc_toLanguageTag(result->icu_id, result->bcp47_id,
+                     ULOC_FULLNAME_CAPACITY, false, &status);
+  return !U_FAILURE(status);
+}
+
+} }  // namespace v8::internal