Wrapper class for memory mapped file on Windows

MemoryMappedFile.hpp

#pragma once

#include <experimental/filesystem>
#include <windows.h>

class MemoryMappedFile {

public:
  using path = std::experimental::filesystem::path;

  MemoryMappedFile(const path &filename) {
    _fileHandle = CreateFileW(filename.wstring().c_str(), GENERIC_READ,
                              FILE_SHARE_READ, NULL, OPEN_EXISTING, NULL, NULL);
    if (_fileHandle == INVALID_HANDLE_VALUE) {
      throw std::runtime_error("Failed to open file");
    }

    GetFileSizeEx(_fileHandle, &_size);

    _mappingHandle =
        CreateFileMapping(_fileHandle, NULL, PAGE_READONLY, 0, 0, NULL);

    if (_mappingHandle == NULL) {
      CloseHandle(_fileHandle);
      throw std::runtime_error("Failed to create memory mapping");
    }

    _view = MapViewOfFile(_mappingHandle, FILE_MAP_READ, 0, 0, 0);

    if (_view == NULL) {
      CloseHandle(_mappingHandle);
      CloseHandle(_fileHandle);
      throw std::runtime_error("Failed to map file");
    }
  }

  ~MemoryMappedFile() {
    UnmapViewOfFile(_view);
    CloseHandle(_mappingHandle);
    CloseHandle(_fileHandle);
  }

  const void *data() const { return _view; }

  size_t size() const { return _size.QuadPart; }

private:
  HANDLE _fileHandle;
  HANDLE _mappingHandle;
  const void *_view;
  LARGE_INTEGER _size;
};