libs/archive/src/unknown_impl.h


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/*
Mod Organizer archive handling

Copyright (C) 2012 Sebastian Herbord, 2020 MO2 Team. All rights reserved.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#ifndef UNKNOWN_IMPL_H
#define UNKNOWN_IMPL_H

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#else
#include <Common/MyWindows.h>
#include <atomic>
#endif

/* This implements a common way of creating classes which implement one or more
 * COM interfaces.
 *
 * Your implementaton should be something like this
 *
 * class MyImplementation :
 *  public interface1,
 *  public interface2 //etc to taste
 * {
 *     UNKNOWN_1_INTERFACE(interface1);
 * or  UNKNOWN_2_INTERFACE(interface1, interface2); etc
 *
 * It would probably be possible to do something very magic with macros
 * that allowed you to do
 * class My_Implmentation : UNKNOWN_IMPL_n(interface1, ...)
 *
 * that did all the above for you, but I can't see how to maintain the braces
 * in order to make the class declaration look nice.
 *
 * You might ask why I have e-implemented this from the 7-zip stuff (sort of).
 *
 * Well,
 *
 * Firstly, the 7zip macros are slightly buggy (they don't null the outpointer
 * if the interface isn't found), and they aren't thread safe.
 *
 * Secondly, although 7-zip has a requirement to run on platforms other than
 * windows, we don't. So I changed this to use the Com functionality supplied
 * by windows, which (potentially) has better debugging facilities
 *
 * Thirdly, this removes a number of dependencies on 7-zip source which aren't
 * really part of the API
 */

#ifdef _WIN32

/* Do not use these macros, use the ones at the bottom */
#define UNKNOWN__INTERFACE_BEGIN                                                       \
public:                                                                                \
  STDMETHOD_(ULONG, AddRef)()                                                          \
  {                                                                                    \
    return ::InterlockedIncrement(&m_RefCount__);                                      \
  }                                                                                    \
                                                                                       \
  STDMETHOD_(ULONG, Release)()                                                         \
  {                                                                                    \
    ULONG res = ::InterlockedDecrement(&m_RefCount__);                                 \
    if (res == 0) {                                                                    \
      delete this;                                                                     \
    }                                                                                  \
    return res;                                                                        \
  }                                                                                    \
                                                                                       \
  STDMETHOD(QueryInterface)(REFGUID iid, void** outObject)                             \
  {                                                                                    \
    if (iid == IID_IUnknown) {

#define UNKNOWN__INTERFACE_UNKNOWN(interface)                                          \
  *outObject = static_cast<IUnknown*>(static_cast<interface*>(this));                  \
  }

#define UNKNOWN__INTERFACE_NAME(interface)                                             \
  else if (iid == IID_##interface)                                                     \
  {                                                                                    \
    *outObject = static_cast<interface*>(this);                                        \
  }

#define UNKNOWN__INTERFACE_END                                                         \
  else                                                                                 \
  {                                                                                    \
    *outObject = nullptr;                                                              \
    return E_NOINTERFACE;                                                              \
  }                                                                                    \
  AddRef();                                                                            \
  return S_OK;                                                                         \
  }                                                                                    \
                                                                                       \
private:                                                                               \
  ULONG m_RefCount__ = 0

#else // Linux

/* Do not use these macros, use the ones at the bottom */
#define UNKNOWN__INTERFACE_BEGIN                                                       \
public:                                                                                \
  STDMETHOD_(ULONG, AddRef)()                                                          \
  {                                                                                    \
    return ++m_RefCount__;                                                             \
  }                                                                                    \
                                                                                       \
  STDMETHOD_(ULONG, Release)()                                                         \
  {                                                                                    \
    ULONG res = --m_RefCount__;                                                        \
    if (res == 0) {                                                                    \
      delete this;                                                                     \
    }                                                                                  \
    return res;                                                                        \
  }                                                                                    \
                                                                                       \
  STDMETHOD(QueryInterface)(REFGUID iid, void** outObject)                             \
  {                                                                                    \
    if (iid == IID_IUnknown) {

#define UNKNOWN__INTERFACE_UNKNOWN(interface)                                          \
  *outObject = static_cast<IUnknown*>(static_cast<interface*>(this));                  \
  }

#define UNKNOWN__INTERFACE_NAME(interface)                                             \
  else if (iid == IID_##interface)                                                     \
  {                                                                                    \
    *outObject = static_cast<interface*>(this);                                        \
  }

#define UNKNOWN__INTERFACE_END                                                         \
  else                                                                                 \
  {                                                                                    \
    *outObject = nullptr;                                                              \
    return E_NOINTERFACE;                                                              \
  }                                                                                    \
  AddRef();                                                                            \
  return S_OK;                                                                         \
  }                                                                                    \
                                                                                       \
private:                                                                               \
  std::atomic<ULONG> m_RefCount__{0}

#endif // _WIN32

/* These are the macros you should be using */
#define UNKNOWN_1_INTERFACE(interface)                                                 \
  UNKNOWN__INTERFACE_BEGIN                                                             \
  UNKNOWN__INTERFACE_UNKNOWN(interface)                                                \
  UNKNOWN__INTERFACE_NAME(interface)                                                   \
  UNKNOWN__INTERFACE_END

#define UNKNOWN_2_INTERFACE(interface1, interface2)                                    \
  UNKNOWN__INTERFACE_BEGIN                                                             \
  UNKNOWN__INTERFACE_UNKNOWN(interface1)                                               \
  UNKNOWN__INTERFACE_NAME(interface1)                                                  \
  UNKNOWN__INTERFACE_NAME(interface2)                                                  \
  UNKNOWN__INTERFACE_END

#define UNKNOWN_3_INTERFACE(interface1, interface2, interface3)                        \
  UNKNOWN__INTERFACE_BEGIN                                                             \
  UNKNOWN__INTERFACE_UNKNOWN(interface1)                                               \
  UNKNOWN__INTERFACE_NAME(interface1)                                                  \
  UNKNOWN__INTERFACE_NAME(interface2)                                                  \
  UNKNOWN__INTERFACE_NAME(interface3)                                                  \
  UNKNOWN__INTERFACE_END

#define UNKNOWN_4_INTERFACE(interface1, interface2, interface3, interface4)            \
  UNKNOWN__INTERFACE_BEGIN                                                             \
  UNKNOWN__INTERFACE_UNKNOWN(interface1)                                               \
  UNKNOWN__INTERFACE_NAME(interface1)                                                  \
  UNKNOWN__INTERFACE_NAME(interface2)                                                  \
  UNKNOWN__INTERFACE_NAME(interface3)                                                  \
  UNKNOWN__INTERFACE_NAME(interface4)                                                  \
  UNKNOWN__INTERFACE_END

#endif  // UNKNOWN_IMPL_H