fune/dom/plugins/ipc/IpdlTuple.h

#ifndef dom_plugins_ipc_ipdltuple_h
#define dom_plugins_ipc_ipdltuple_h

#include "mozilla/plugins/FunctionBrokerIPCUtils.h"
#include "mozilla/Variant.h"

namespace mozilla {
namespace plugins {

/**
 * IpdlTuple is used by automatic function brokering to pass parameter
 * lists for brokered functions.  It supports a limited set of types
 * (see IpdlTuple::IpdlTupleElement).
 */
class IpdlTuple
{
public:
  uint32_t NumElements() const { return mTupleElements.Length(); }

  template<typename EltType>
  EltType* Element(uint32_t index)
  {
    if ((index >= mTupleElements.Length()) ||
        !mTupleElements[index].GetVariant().is<EltType>()) {
      return nullptr;
    }
    return &mTupleElements[index].GetVariant().as<EltType>();
  }

  template<typename EltType>
  const EltType* Element(uint32_t index) const
  {
    return const_cast<IpdlTuple*>(this)->Element<EltType>(index);
  }

  template <typename EltType>
  void AddElement(const EltType& aElt)
  {
    IpdlTupleElement* newEntry = mTupleElements.AppendElement();
    newEntry->Set(aElt);
  }

private:
  struct InvalidType {};

  // Like Variant but with a default constructor.
  template <typename ... Types>
  struct MaybeVariant
  {
  public:
    MaybeVariant() : mValue(InvalidType()) {}
    MaybeVariant(MaybeVariant&& o) : mValue(Move(o.mValue)) {}

    template <typename Param> void Set(const Param& aParam)
    {
      mValue = mozilla::AsVariant(aParam);
    }

    typedef mozilla::Variant<InvalidType, Types...> MaybeVariantType;
    MaybeVariantType& GetVariant() { return mValue; }
    const MaybeVariantType& GetVariant() const { return mValue; }

  private:
    MaybeVariantType mValue;
  };

#if defined(XP_WIN)
  typedef MaybeVariant<int8_t,uint8_t,int16_t,uint16_t,int32_t,uint32_t,
                       int64_t,uint64_t,nsCString,bool,OpenFileNameIPC,
                       OpenFileNameRetIPC,NativeWindowHandle,
                       IPCSchannelCred,IPCInternetBuffers,StringArray,
                       IPCPrintDlg> IpdlTupleElement;
#else
  typedef MaybeVariant<int8_t,uint8_t,int16_t,uint16_t,int32_t,uint32_t,
                       int64_t,uint64_t,nsCString,bool> IpdlTupleElement;
#endif // defined(XP_WIN)

  friend struct IPC::ParamTraits<IpdlTuple>;
  friend struct IPC::ParamTraits<IpdlTuple::IpdlTupleElement>;
  friend struct IPC::ParamTraits<IpdlTuple::InvalidType>;

  nsTArray<IpdlTupleElement> mTupleElements;
};

template <> template<>
inline void IpdlTuple::IpdlTupleElement::Set<nsDependentCSubstring>(const nsDependentCSubstring& aParam)
{
  mValue = MaybeVariantType(mozilla::VariantType<nsCString>(), aParam);
}

} // namespace plugins
} // namespace mozilla

namespace IPC {

using namespace mozilla::plugins;

template <>
struct ParamTraits<IpdlTuple>
{
  typedef IpdlTuple paramType;

  static void Write(Message* aMsg, const paramType& aParam)
  {
    WriteParam(aMsg, aParam.mTupleElements);
  }

  static bool Read(const Message* aMsg, PickleIterator* aIter,
                   paramType* aParam)
  {
    return ReadParam(aMsg, aIter, &aParam->mTupleElements);
  }

  static void Log(const paramType& aParam, std::wstring* aLog)
  {
    LogParam(aParam.mTupleElements, aLog);
  }
};

template<>
struct ParamTraits<IpdlTuple::IpdlTupleElement>
{
  typedef IpdlTuple::IpdlTupleElement paramType;

  static void Write(Message* aMsg, const paramType& aParam)
  {
    MOZ_RELEASE_ASSERT(!aParam.GetVariant().is<IpdlTuple::InvalidType>());
    WriteParam(aMsg, aParam.GetVariant());
  }

  static bool Read(const Message* aMsg, PickleIterator* aIter,
                   paramType* aParam)
  {
    bool ret = ReadParam(aMsg, aIter, &aParam->GetVariant());
    MOZ_RELEASE_ASSERT(!aParam->GetVariant().is<IpdlTuple::InvalidType>());
    return ret;
  }

  struct LogMatcher
  {
    explicit LogMatcher(std::wstring* aLog) : mLog(aLog) {}

    template <typename EntryType>
    void match(const EntryType& aParam)
    {
      LogParam(aParam, mLog);
    }

  private:
    std::wstring* mLog;
  };

  static void Log(const paramType& aParam, std::wstring* aLog)
  {
    aParam.GetVariant().match(LogMatcher(aLog));
  }
};

template<>
struct ParamTraits<IpdlTuple::InvalidType>
{
  typedef IpdlTuple::InvalidType paramType;

  static void Write(Message* aMsg, const paramType& aParam)
  {
    MOZ_ASSERT_UNREACHABLE("Attempt to serialize an invalid tuple element");
  }

  static bool Read(const Message* aMsg, PickleIterator* aIter,
                   paramType* aParam)
  {
    MOZ_ASSERT_UNREACHABLE("Attempt to deserialize an invalid tuple element");
    return false;
  }

  static void Log(const paramType& aParam, std::wstring* aLog)
  {
    aLog->append(L"<Invalid Tuple Entry>");
  }
};

} // namespace IPC

#endif /* dom_plugins_ipc_ipdltuple_h */