itkInternationalizationIOHelpers.h

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkInternationalizationIOHelpers.h,v $
  Language:  C++
  Date:      $Date: 2010-01-13 20:16:01 $
  Version:   $Revision: 1.3 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkInternationalizationIOHelpers_h
#define __itkInternationalizationIOHelpers_h

// This header provides some helper functions to deal with unicode filenames
// It is mainly directed towards being able to use utf-8 encoded filenames
// on windows.
// This should help better dealing with internationalization (a.k.a i18n)

#include "itkConfigure.h"
#include "itkMacro.h"

#ifdef ITK_HAVE_UNISTD_H
# include <unistd.h> // for unlink
#else
# include <io.h>
#endif

#include <stdio.h> // Borland needs this (cstdio does not work easy)
#include <fcntl.h>
#include <iostream>
#include <string>
#include <sys/stat.h>

// Find out how to handle unicode filenames on windows:
// * VS>=8.0 has _wopen and _wfopen and can open a (i/o)fstream using a wide string
// * cygwin has NO _wopen an NO _wfopen. If you really need unicode
//   filenames on cygwin, just use cygwin >= 1.7 for now, it works with utf8
//   natively. Alternatively, we could try and use pure win32 functions such as
//   CreateFileW and convert the win32 file handle using _open_osfhandle and _fdopen
// * VS6.0 has _wopen and _wfopen but cannot open a (i/o)fstream using a wide string
//   nor can it compile fdstream => disable unicode filename support
// * Borland c++, VS7.x and MinGW have _wopen and _wfopen but cannot open a
//   (i/o)fstream using a wide string. They can however compile fdstream

#if defined(ITK_SUPPORTS_WCHAR_T_FILENAME_CSTYLEIO) \
   && ( defined(ITK_SUPPORTS_WCHAR_T_FILENAME_IOSTREAMS_CONSTRUCTORS) || defined(ITK_SUPPORTS_FDSTREAM_HPP) )
# define LOCAL_USE_WIN32_WOPEN 1
# include <windows.h> // required by winnls.h
# include <winnls.h> // for MultiByteToWideChar
#else
# define LOCAL_USE_WIN32_WOPEN 0
#endif

#if (LOCAL_USE_WIN32_WOPEN && defined(ITK_SUPPORTS_WCHAR_T_FILENAME_IOSTREAMS_CONSTRUCTORS)) \
   || (!LOCAL_USE_WIN32_WOPEN)
# define LOCAL_USE_FDSTREAM 0
# include <fstream>
#else
# define LOCAL_USE_FDSTREAM 1
# include "fdstream.hpp"
#endif


namespace itk
{
namespace i18n
{

// Check if the string is correctly encoded
#if LOCAL_USE_WIN32_WOPEN
inline bool IsStringEncodingValid(const std::string & str)
{
  // Check if the string is really encoded in utf-8 using windows API
  // MultiByteToWideChar returns 0 if there was a problem during conversion
  // when given the MB_ERR_INVALID_CHARS flag
  const int utf16_size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, str.c_str(),
                                             static_cast<int>(str.length()), 0, 0);
  return (utf16_size != 0);
}
#else
inline bool IsStringEncodingValid(const std::string & itkNotUsed( str ) )
{
  return true;
}
#endif

#if LOCAL_USE_WIN32_WOPEN
// Convert a utf8 encoded std::string to a utf16 encoded wstring on windows
inline std::wstring Utf8StringToWString( const std::string & str )
{
  // We do not set the MB_ERR_INVALID_CHARS to do an approximate conversion when non
  // utf8 characters are found. An alternative would be to throw an exception

  // First get the size
  const int utf16_size = MultiByteToWideChar(CP_UTF8, 0, str.c_str(),
                                             static_cast<int>(str.length()), 0, 0);

  // Now do the conversion
  std::wstring wstr;
  wstr.resize(utf16_size);
  MultiByteToWideChar(CP_UTF8, 0, str.c_str(),
                      static_cast<int>(str.length()), &wstr[0], utf16_size);
  
  return wstr;
}

#endif

// Get a file descriptor from a filename (using utf8 to wstring
// on windows if requested) without specifying any specific permissions
inline int I18nOpen( const std::string & str, const int & flags )
{
#if LOCAL_USE_WIN32_WOPEN
  // cygwin has NO _wopen but mingw has
  // If you really need unicode filenames on cygwin, just use cygwin >= 1.7
  // Convert to utf16
  const std::wstring str_utf16 = Utf8StringToWString( str );
  return _wopen(str_utf16.c_str(), flags);
#else
  return open(str.c_str(), flags);
#endif
}

// Get a file descriptor from a filename (using utf8 to wstring
// on windows if requested)
inline int I18nOpen( const std::string & str, const int & flags, const int & mode )
{
#if LOCAL_USE_WIN32_WOPEN
  // cygwin has NO _wopen but mingw has
  // If you really need unicode filenames on cygwin, just use cygwin >= 1.7
  // Convert to utf16
  const std::wstring str_utf16 = Utf8StringToWString( str );
  return _wopen(str_utf16.c_str(), flags, mode);
#else
  return open(str.c_str(), flags, mode);
#endif
}

// Reading wrapper around I18nOpen to avoid explicitely specifying the flags
inline int I18nOpenForReading( const std::string & str )
{
#if LOCAL_USE_WIN32_WOPEN
  return I18nOpen(str, _O_RDONLY | _O_BINARY );
#else
  return I18nOpen(str, O_RDONLY );
#endif
}

// Writting wrapper around I18nOpen to avoid explicitely specifying the flags
inline int I18nOpenForWritting( const std::string & str, const bool append = false )
{
#if LOCAL_USE_WIN32_WOPEN
  if (!append) return I18nOpen(str, _O_WRONLY | _O_CREAT | _O_BINARY, _S_IREAD | _S_IWRITE );
  else return I18nOpen(str, _O_WRONLY | _O_CREAT | _O_APPEND | _O_BINARY, _S_IREAD | _S_IWRITE );
#else
  if (!append) return I18nOpen(str, O_WRONLY | O_CREAT, S_IREAD | S_IWRITE );
  else return I18nOpen(str, O_WRONLY | O_CREAT | O_APPEND, S_IREAD | S_IWRITE );
#endif
}

// Get a FILE * pointer from a filename (using utf8 to wstring
// on windows if requested)
inline FILE * I18nFopen( const std::string & str, const std::string & mode )
{
#if LOCAL_USE_WIN32_WOPEN
  // cygwin has NO _wfopen but mingw has
  // If you really need unicode filenames on cygwin, just use cygwin >= 1.7
  // Convert to utf16
  const std::wstring str_utf16 = Utf8StringToWString( str );
  const std::wstring mode_utf16 = Utf8StringToWString( mode );
  return _wfopen(str_utf16.c_str(), mode_utf16.c_str());
#else
  return fopen(str.c_str(), mode.c_str());
#endif
}

#if LOCAL_USE_FDSTREAM
class I18nOfstream : public std::ostream 
{
public:
  I18nOfstream( const char * str, 
    std::ios_base::openmode mode = std::ios_base::out )
    : std::ostream(0)
    , m_fd( I18nOpenForWritting( str, (mode & std::ios::app)?true:false ) )
    , m_buf( m_fd )
    {
    this->rdbuf(&m_buf);
    }

  ~I18nOfstream() { this->close(); }

  bool is_open() { return (m_fd!=-1); }

  void close()
    {
    if ( m_fd!=-1 ) ::close( m_fd );
    m_fd = -1;
    }

private:
  int m_fd;
  itk::fdoutbuf m_buf;
};

class I18nIfstream : public std::istream 
{
public:
  I18nIfstream( const char * str, 
    std::ios_base::openmode mode = std::ios_base::in )
    : std::istream(0)
    , m_fd( I18nOpenforreading( str ) )
    , m_buf( m_fd )
    {
    this->rdbuf(&m_buf);
    }

  ~I18nIfstream() { this->close(); }

  bool is_open() { return (m_fd!=-1); }

  void close()
    {
    if ( m_fd!=-1 ) ::close( m_fd );
    m_fd = -1;
    }

private:
  int m_fd;
  itk::fdinbuf m_buf;
};
#elif LOCAL_USE_WIN32_WOPEN
class I18nOfstream : public std::ofstream
{
public:
  I18nOfstream( const char * str, std::ios_base::openmode mode = std::ios_base::out )
    : std::ofstream( Utf8StringToWString(str).c_str(), mode )
    {
    }
};

class I18nIfstream : public std::ifstream
{
public:
  I18nIfstream( const char * str, std::ios_base::openmode mode = std::ios_base::in )
    : std::ifstream( Utf8StringToWString(str).c_str(), mode )
    {
    }
};
#else
typedef std::ofstream I18nOfstream;
typedef std::ifstream I18nIfstream;
#endif

} // end namespace
} // end namespace


#undef LOCAL_USE_WIN32_WOPEN
#undef LOCAL_USE_FDSTREAM

#endif  /* __itkInternationalizationIOHelpers_h */