ipc/glue/IPCMessageUtilsSpecializations.cpp

   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 #include "IPCMessageUtilsSpecializations.h"
   8 #include "nsGkAtoms.h"
   9
  10 namespace IPC {
  11
  12 static const uint16_t kDynamicAtomToken = 0xffff;
  13 static const uint16_t kAtomsCount =
  14     static_cast<uint16_t>(mozilla::detail::GkAtoms::Atoms::AtomsCount);
  15
  16 static_assert(static_cast<size_t>(
  17                   mozilla::detail::GkAtoms::Atoms::AtomsCount) == kAtomsCount,
  18               "Number of static atoms must fit in a uint16_t");
  19
  20 static_assert(kDynamicAtomToken >= kAtomsCount,
  21               "Exceeded supported number of static atoms");
  22
  23 /* static */
  24 void ParamTraits<nsAtom*>::Write(MessageWriter* aWriter, const nsAtom* aParam) {
  25   MOZ_ASSERT(aParam);
  26
  27   if (aParam->IsStatic()) {
  28     const nsStaticAtom* atom = aParam->AsStatic();
  29     uint16_t index = static_cast<uint16_t>(nsGkAtoms::IndexOf(atom));
  30     MOZ_ASSERT(index < kAtomsCount);
  31     WriteParam(aWriter, index);
  32     return;
  33   }
  34   WriteParam(aWriter, kDynamicAtomToken);
  35   nsDependentAtomString atomStr(aParam);
  36   // nsDependentAtomString is serialized as its base, nsString, but we
  37   // can be explicit about it.
  38   nsString& str = atomStr;
  39   WriteParam(aWriter, str);
  40 }
  41
  42 /* static */
  43 bool ParamTraits<nsAtom*>::Read(MessageReader* aReader,
  44                                 RefPtr<nsAtom>* aResult) {
  45   uint16_t token;
  46   if (!ReadParam(aReader, &token)) {
  47     return false;
  48   }
  49   if (token != kDynamicAtomToken) {
  50     if (token >= kAtomsCount) {
  51       return false;
  52     }
  53     *aResult = nsGkAtoms::GetAtomByIndex(token);
  54     return true;
  55   }
  56
  57   nsAutoString str;
  58   if (!ReadParam(aReader, static_cast<nsString*>(&str))) {
  59     return false;
  60   }
  61
  62   *aResult = NS_Atomize(str);
  63   MOZ_ASSERT(*aResult);
  64   return true;
  65 }
  66
  67 }  // namespace IPC