common/alfstream.h

   1 #ifndef AL_FSTREAM_H
   2 #define AL_FSTREAM_H
   3
   4 #ifdef _WIN32
   5
   6 #define WIN32_LEAN_AND_MEAN
   7 #include <windows.h>
   8
   9 #include <array>
  10 #include <string>
  11 #include <fstream>
  12
  13
  14 namespace al {
  15
  16 // Windows' std::ifstream fails with non-ANSI paths since the standard only
  17 // specifies names using const char* (or std::string). MSVC has a non-standard
  18 // extension using const wchar_t* (or std::wstring?) to handle Unicode paths,
  19 // but not all Windows compilers support it. So we have to make our own istream
  20 // that accepts UTF-8 paths and forwards to Unicode-aware I/O functions.
  21 class filebuf final : public std::streambuf {
  22     std::array<char_type,4096> mBuffer;
  23     HANDLE mFile{INVALID_HANDLE_VALUE};
  24
  25     int_type underflow() override;
  26     pos_type seekoff(off_type offset, std::ios_base::seekdir whence, std::ios_base::openmode mode) override;
  27     pos_type seekpos(pos_type pos, std::ios_base::openmode mode) override;
  28
  29 public:
  30     filebuf() = default;
  31     ~filebuf() override;
  32
  33     bool open(const wchar_t *filename, std::ios_base::openmode mode);
  34     bool open(const char *filename, std::ios_base::openmode mode);
  35
  36     bool is_open() const noexcept { return mFile != INVALID_HANDLE_VALUE; }
  37 };
  38
  39 // Inherit from std::istream to use our custom streambuf
  40 class ifstream final : public std::istream {
  41     filebuf mStreamBuf;
  42
  43 public:
  44     ifstream(const wchar_t *filename, std::ios_base::openmode mode = std::ios_base::in);
  45     ifstream(const std::wstring &filename, std::ios_base::openmode mode = std::ios_base::in)
  46       : ifstream(filename.c_str(), mode) { }
  47     ifstream(const char *filename, std::ios_base::openmode mode = std::ios_base::in);
  48     ifstream(const std::string &filename, std::ios_base::openmode mode = std::ios_base::in)
  49       : ifstream(filename.c_str(), mode) { }
  50     ~ifstream() override;
  51
  52     bool is_open() const noexcept { return mStreamBuf.is_open(); }
  53 };
  54
  55 } // namespace al
  56
  57 #else /* _WIN32 */
  58
  59 #include <fstream>
  60
  61 namespace al {
  62
  63 using filebuf = std::filebuf;
  64 using ifstream = std::ifstream;
  65
  66 } // namespace al
  67
  68 #endif /* _WIN32 */
  69
  70 #endif /* AL_FSTREAM_H */