#include <string>
#include <windows.h>

template<typename T>
class MapFile
{
public:
  // ctor to create the initial file mapping
  explicit MapFile(const std::string &mapName,
                   DWORD maxSizeLow = 1000,
                   DWORD maxSizeHigh = 0) :
    pMapFile(0),
    pObj(0),
    handle(0)
  {
    // create new file mapping
    handle =
      ::CreateFileMapping(reinterpret_cast<HANDLE>(0xffffffff),
                                 NULL,
                                 PAGE_READWRITE,
                                 maxSizeHigh,
                                 maxSizeLow,
                                 mapName.c_str());
    if (handle == NULL)
    {
      throw int(::GetLastError()); // your error code here
    }

    pMapFile = static_cast<T *>(::MapViewOfFile(handle,
                                                FILE_MAP_ALL_ACCESS,
                                                0, // high offset
                                                0, // low offset
                                                0)); // num bytes to
                                                     // map
    if (pMapFile == NULL)
    {
      throw int(::GetLastError());
    }

    // call placement new to create an object of type T, place it
    // in the location pointed to by pMapFile and call the ctor
    pObj = new (pMapFile) T;
  }

  // ctor to open an existing file mapping
  MapFile(const std::string &mapName, bool inherit) :
    pMapFile(0),
    pObj(0),
    handle(0)
  {
    // open existing file mapping
    handle = ::OpenFileMapping(FILE_MAP_ALL_ACCESS,
                               inherit,
                               mapName.c_str());
    if (handle == NULL)
    {
      throw int(::GetLastError());
    }

    pMapFile = static_cast<T *>(::MapViewOfFile(handle,
                                                FILE_MAP_ALL_ACCESS,
                                                0, // high offset
                                                0, // low offset
                                                0)); // num bytes to
                                                     // map
    if (pMapFile == NULL)
    {
      throw int(::GetLastError());
    }

    //since this is an existing object, just point to it...no need to
    //call ctor again
    pObj = pMapFile;
  }

  ~MapFile()
  {
    ::UnmapViewOfFile(pMapFile);
    pMapFile = 0;
    pObj->~T();
    pObj = 0;
    ::CloseHandle(handle);
  }

  T *get() { return pObj; }

//  friend class T;

private:
  // do not allow
  MapFile();
  MapFile(const MapFile &rhs);
  MapFile &operator=(const MapFile &rhs);

  T *pMapFile; // the data, I own
  T *pObj; // the object to call methods on...I own and call
  HANDLE handle;
};