ipc/glue/IPDLParamTraits.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_ipc_IPDLParamTraits_h
   8 #define mozilla_ipc_IPDLParamTraits_h
   9
  10 #include "chrome/common/ipc_message_utils.h"
  11 #include "ipc/IPCMessageUtilsSpecializations.h"
  12 #include "mozilla/UniquePtr.h"
  13 #include "mozilla/Variant.h"
  14
  15 #include "nsTArray.h"
  16
  17 #include <type_traits>
  18
  19 namespace mozilla {
  20 namespace ipc {
  21
  22 class IProtocol;
  23
  24 //
  25 // IPDLParamTraits was an extended version of ParamTraits. Unlike ParamTraits,
  26 // IPDLParamTraits passes an additional IProtocol* argument to the
  27 // write and read methods.
  28 //
  29 // Previously this was required for serializing and deserializing types which
  30 // require knowledge of which protocol they're being sent over, however the
  31 // actor is now available through `IPC::Message{Writer,Reader}::GetActor()` so
  32 // the extra argument is no longer necessary. Please use `IPC::ParamTraits` in
  33 // the future.
  34 //
  35 // Types which implement IPDLParamTraits are also supported by ParamTraits.
  36 //
  37 template <typename P>
  38 struct IPDLParamTraits {};
  39
  40 //
  41 // WriteIPDLParam and ReadIPDLParam are like IPC::WriteParam and IPC::ReadParam,
  42 // however, they also accept a redundant extra actor argument.
  43 //
  44 // NOTE: WriteIPDLParam takes a universal reference, so that it can support
  45 // whatever reference type is supported by the underlying ParamTraits::Write
  46 // implementation.
  47 //
  48 template <typename P>
  49 static MOZ_NEVER_INLINE void WriteIPDLParam(IPC::MessageWriter* aWriter,
  50                                             IProtocol* aActor, P&& aParam) {
  51   MOZ_ASSERT(aActor == aWriter->GetActor());
  52   IPC::WriteParam(aWriter, std::forward<P>(aParam));
  53 }
  54
  55 template <typename P>
  56 static MOZ_NEVER_INLINE bool ReadIPDLParam(IPC::MessageReader* aReader,
  57                                            IProtocol* aActor, P* aResult) {
  58   MOZ_ASSERT(aActor == aReader->GetActor());
  59   return IPC::ReadParam(aReader, aResult);
  60 }
  61
  62 }  // namespace ipc
  63 }  // namespace mozilla
  64
  65 #endif  // defined(mozilla_ipc_IPDLParamTraits_h)