dom/quota/StringifyUtils.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_quota_stringifyutils_h__
   8 #define mozilla_dom_quota_stringifyutils_h__
   9
  10 #include "mozilla/ThreadLocal.h"
  11 #include "nsTHashSet.h"
  12 #include "nsLiteralString.h"
  13
  14 namespace mozilla {
  15
  16 // Use these constants for common delimiters. Note that `Stringify` already
  17 // encloses each call to `DoStringify` with `kStringify[Start/End]Instance`.
  18 constexpr auto kStringifyDelimiter = "|"_ns;
  19 constexpr auto kStringifyStartSet = "["_ns;
  20 constexpr auto kStringifyEndSet = "]"_ns;
  21 constexpr auto kStringifyStartInstance = "{"_ns;
  22 constexpr auto kStringifyEndInstance = "}"_ns;
  23
  24 // A Stringifyable class provides a method `Stringify` that returns a string
  25 // representation of the class content.
  26 //
  27 // It's content is just appended by the override of `DoStringify` but
  28 // `Stringifyable` ensures that we won't call `DoStringify` twice for the same
  29 // call and instance. A single `DoStringify` function thus needs not to be
  30 // aware of "should I `Stringify` the content of this member or not", it can
  31 // just do it always.
  32 //
  33 // Stringifyable does not bloat the object by additional members but uses
  34 // thread local memory only when needed.
  35 class Stringifyable {
  36  public:
  37   void Stringify(nsACString& aData);
  38
  39   static void InitTLS();
  40
  41  private:
  42   virtual void DoStringify(nsACString& aData) = 0;
  43
  44   bool IsActive();
  45   void SetActive(bool aIsActive);
  46
  47   static MOZ_THREAD_LOCAL(nsTHashSet<Stringifyable*>*)
  48       sActiveStringifyableInstances;
  49 };
  50
  51 }  // namespace mozilla
  52
  53 #endif  // mozilla_dom_quota_stringifyutils_h__