xpcom/components/ModuleUtils.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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_GenericModule_h
   8 #define mozilla_GenericModule_h
   9
  10 #include <type_traits>
  11
  12 #include "mozilla/AlreadyAddRefed.h"
  13 #include "mozilla/Attributes.h"
  14 #include "mozilla/Module.h"
  15
  16 #define NS_GENERIC_FACTORY_CONSTRUCTOR(_InstanceClass)                         \
  17   static nsresult _InstanceClass##Constructor(REFNSIID aIID, void** aResult) { \
  18     RefPtr<_InstanceClass> inst;                                               \
  19                                                                                \
  20     *aResult = nullptr;                                                        \
  21                                                                                \
  22     inst = new _InstanceClass();                                               \
  23     return inst->QueryInterface(aIID, aResult);                                \
  24   }
  25
  26 #define NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod)       \
  27   static nsresult _InstanceClass##Constructor(REFNSIID aIID, void** aResult) { \
  28     nsresult rv;                                                               \
  29                                                                                \
  30     RefPtr<_InstanceClass> inst;                                               \
  31                                                                                \
  32     *aResult = nullptr;                                                        \
  33                                                                                \
  34     inst = new _InstanceClass();                                               \
  35     rv = inst->_InitMethod();                                                  \
  36     if (NS_SUCCEEDED(rv)) {                                                    \
  37       rv = inst->QueryInterface(aIID, aResult);                                \
  38     }                                                                          \
  39                                                                                \
  40     return rv;                                                                 \
  41   }
  42
  43 namespace mozilla {
  44 namespace detail {
  45
  46 template <typename T>
  47 struct RemoveAlreadyAddRefed {
  48   using Type = T;
  49 };
  50
  51 template <typename T>
  52 struct RemoveAlreadyAddRefed<already_AddRefed<T>> {
  53   using Type = T;
  54 };
  55
  56 }  // namespace detail
  57 }  // namespace mozilla
  58
  59 // 'Constructor' that uses an existing getter function that gets a singleton.
  60 #define NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(_InstanceClass, _GetterProc)  \
  61   static nsresult _InstanceClass##Constructor(REFNSIID aIID, void** aResult) { \
  62     RefPtr<_InstanceClass> inst;                                               \
  63                                                                                \
  64     *aResult = nullptr;                                                        \
  65                                                                                \
  66     using T =                                                                  \
  67         mozilla::detail::RemoveAlreadyAddRefed<decltype(_GetterProc())>::Type; \
  68     static_assert(                                                             \
  69         std::is_same_v<already_AddRefed<T>, decltype(_GetterProc())>,          \
  70         "Singleton constructor must return already_AddRefed");                 \
  71     static_assert(                                                             \
  72         std::is_base_of<_InstanceClass, T>::value,                             \
  73         "Singleton constructor must return correct already_AddRefed");         \
  74     inst = _GetterProc();                                                      \
  75     if (nullptr == inst) {                                                     \
  76       return NS_ERROR_OUT_OF_MEMORY;                                           \
  77     }                                                                          \
  78     return inst->QueryInterface(aIID, aResult);                                \
  79   }
  80
  81 #endif  // mozilla_GenericModule_h