nsLanguageAtomService.h

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/* -*- 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/. */

/*

 * The nsILanguageAtomService provides a mapping from languages or charsets

 * to language groups, and access to the system locale language.

*/

#ifndef nsLanguageAtomService_h_

#define nsLanguageAtomService_h_

#include "mozilla/NotNull.h"

#include "nsCOMPtr.h"

#include "nsAtomHashKeys.h"

#include "nsTHashMap.h"

namespace mozilla {

class Encoding;

class nsLanguageAtomService final {

  using Encoding = mozilla::Encoding;

  template <typename T>

  using NotNull = mozilla::NotNull<T>;

 public:

  static nsLanguageAtomService* GetService();

  static void Shutdown();

  nsStaticAtom* LookupLanguage(const nsACString& aLanguage);

  already_AddRefed<nsAtom> LookupCharSet(NotNull<const Encoding*> aCharSet);

  nsAtom* GetLocaleLanguage();

  // Returns the language group that the specified language is a part of.

//

  // aNeedsToCache is used for two things.  If null, it indicates that

  // the nsLanguageAtomService is safe to cache the result of the

  // language group lookup, either because we're on the main thread,

  // or because we're on a style worker thread but the font lock has

  // been acquired.  If non-null, it indicates that it's not safe to

  // cache the result of the language group lookup (because we're on

  // a style worker thread without the lock acquired).  In this case,

  // GetLanguageGroup will store true in *aNeedsToCache true if we

  // would have cached the result of a new lookup, and false if we

  // were able to use an existing cached result.  Thus, callers that

  // get a true *aNeedsToCache outparam value should make an effort

  // to re-call GetLanguageGroup when it is safe to cache, to avoid

  // recomputing the language group again later.

  nsStaticAtom* GetLanguageGroup(nsAtom* aLanguage,

                                 bool* aNeedsToCache = nullptr);

  nsStaticAtom* GetUncachedLanguageGroup(nsAtom* aLanguage) const;

 private:

  nsTHashMap<RefPtr<nsAtom>, nsStaticAtom*> mLangToGroup;

  RefPtr<nsAtom> mLocaleLanguage;

};

#endif