Issue #1210 - Introduce an internal API to get configured application locales.

en-US will always be added as a fallback, to make things simpler down the line
and avoid error checking all over the place.

3 files changed, 167 insertions, 0 deletions

diff --git a/intl/locale/LocaleService.cpp b/intl/locale/LocaleService.cpp
new file mode 100644
index 0000000000..55542dc1a9
--- /dev/null
+++ b/intl/locale/LocaleService.cpp
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LocaleService.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/Services.h"
+#include "nsIObserverService.h"
+#include "nsIToolkitChromeRegistry.h"
+
+using namespace mozilla::intl;
+
+/**
+ * This function performs the actual language negotiation for the API.
+ *
+ * Currently it collects the locale ID used by nsChromeRegistry and
+ * adds hardcoded "en-US" locale as a fallback.
+ */
+static void
+ReadAppLocales(nsTArray<nsCString>& aRetVal)
+{
+  nsAutoCString uaLangTag;
+  nsCOMPtr<nsIToolkitChromeRegistry> cr =
+    mozilla::services::GetToolkitChromeRegistryService();
+  if (cr) {
+    cr->GetSelectedLocale(NS_LITERAL_CSTRING("global"), true, uaLangTag);
+  }
+  if (!uaLangTag.IsEmpty()) {
+    aRetVal.AppendElement(uaLangTag);
+  }
+
+  if (!uaLangTag.EqualsLiteral("en-US")) {
+    aRetVal.AppendElement(NS_LITERAL_CSTRING("en-US"));
+  }
+}
+
+mozilla::StaticAutoPtr<LocaleService> LocaleService::sInstance;
+
+LocaleService* LocaleService::GetInstance()
+{
+  if (!sInstance) {
+    sInstance = new LocaleService();
+    ClearOnShutdown(&sInstance);
+  }
+  return sInstance;
+}
+
+void
+LocaleService::GetAppLocales(nsTArray<nsCString>& aRetVal)
+{
+  if (mAppLocales.IsEmpty()) {
+    ReadAppLocales(mAppLocales);
+  }
+  aRetVal = mAppLocales;
+}
+
+void
+LocaleService::GetAppLocale(nsACString& aRetVal)
+{
+  if (mAppLocales.IsEmpty()) {
+    ReadAppLocales(mAppLocales);
+  }
+  aRetVal = mAppLocales[0];
+}
+
+void
+LocaleService::Refresh()
+{
+  nsTArray<nsCString> newLocales;
+  ReadAppLocales(newLocales);
+
+  if (mAppLocales != newLocales) {
+    mAppLocales = Move(newLocales);
+    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+    if (obs) {
+      obs->NotifyObservers(nullptr, "intl:app-locales-changed", nullptr);
+    }
+  }
+}
\ No newline at end of file
diff --git a/intl/locale/LocaleService.h b/intl/locale/LocaleService.h
new file mode 100644
index 0000000000..e5228418c4
--- /dev/null
+++ b/intl/locale/LocaleService.h
@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode:nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_intl_LocaleService_h__
+#define mozilla_intl_LocaleService_h__
+
+#include "mozilla/StaticPtr.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace intl {
+
+
+/**
+ * LocaleService is a manager of language negotiation in Gecko.
+ *
+ * It's intended to be the core place for collecting available and
+ * requested languages and negotiating them to produce a fallback
+ * chain of locales for the application.
+ */
+class LocaleService
+{
+public:
+  static LocaleService* GetInstance();
+
+  /**
+   * Returns a list of locales that the application should be localized to.
+   *
+   * The result is a sorted list of valid locale IDs and it should be
+   * used for all APIs that accept list of locales, like ECMA402 and L10n APIs.
+   *
+   * This API always returns at least one locale.
+   *
+   * Example: ["en-US", "de", "pl", "sr-Cyrl", "zh-Hans-HK"]
+   *
+   * Usage:
+   * nsTArray<nsCString> appLocales;
+   * LocaleService::GetInstance()->GetAppLocales(appLocales);
+   */
+  void GetAppLocales(nsTArray<nsCString>& aRetVal);
+
+  /**
+   * Returns the best locale that the application should be localized to.
+   *
+   * The result is a valid locale IDs and it should be
+   * used for all APIs that do not handle language negotiation.
+   *
+   * Where possible, GetAppLocales should be preferred over this API and
+   * all callsites should handle some form of "best effort" language
+   * negotiation to respect user preferences in case the use case does
+   * not have data for the first locale in the list.
+   *
+   * Example: "zh-Hans-HK"
+   *
+   * Usage:
+   * nsAutoCString appLocale;
+   * LocaleService::GetInstance()->GetAppLocale(appLocale);
+   */
+  void GetAppLocale(nsACString& aRetVal);
+
+  /**
+   * Triggers a refresh of the language negotiation process.
+   *
+   * If the result differs from the previous list, it will additionally
+   * trigger a global event "intl:app-locales-changed".
+   */
+  void Refresh();
+
+protected:
+  nsTArray<nsCString> mAppLocales;
+
+private:
+  static StaticAutoPtr<LocaleService> sInstance;
+};
+
+} // intl
+} // namespace mozilla
+
+#endif /* mozilla_intl_LocaleService_h__ */
diff --git a/intl/locale/moz.build b/intl/locale/moz.build
index 94a30873ba..2ba1c6679a 100644
--- a/intl/locale/moz.build
+++ b/intl/locale/moz.build
@@ -35,7 +35,12 @@ EXPORTS += [
     'nsWin32Locale.h',
 ]
 
+EXPORTS.mozilla.intl += [
+    'LocaleService.h'
+]
+
 UNIFIED_SOURCES += [
+    'LocaleService.cpp',
     'nsCollation.cpp',
     'nsIDateTimeFormat.cpp',
     'nsLanguageAtomService.cpp',