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boost/filesystem/path_traits.hpp

//  filesystem path_traits.hpp  --------------------------------------------------------//

//  Copyright Beman Dawes 2009

//  Distributed under the Boost Software License, Version 1.0.
//  See http://www.boost.org/LICENSE_1_0.txt

//  Library home page: http://www.boost.org/libs/filesystem

#ifndef BOOST_FILESYSTEM_PATH_TRAITS_HPP
#define BOOST_FILESYSTEM_PATH_TRAITS_HPP

#include <boost/config.hpp>

# if defined( BOOST_NO_STD_WSTRING )
#   error Configuration not supported: Boost.Filesystem V3 and later requires std::wstring support
# endif

#include <boost/filesystem/config.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/type_traits/is_array.hpp>
#include <boost/type_traits/decay.hpp>
#include <boost/system/error_code.hpp>
#include <cwchar>  // for mbstate_t
#include <string>
#include <vector>
#include <list>
#include <iterator>
#include <locale>
#include <boost/assert.hpp>
// #include <iostream>   //**** comment me out ****

#include <boost/config/abi_prefix.hpp> // must be the last #include

namespace boost { namespace filesystem {

  BOOST_FILESYSTEM_DECL const system::error_category& codecvt_error_category();
  //  uses std::codecvt_base::result used for error codes:
  //
  //    ok:       Conversion successful.
  //    partial:  Not all source characters converted; one or more additional source
  //              characters are needed to produce the final target character, or the
  //              size of the target intermediate buffer was too small to hold the result.
  //    error:    A character in the source could not be converted to the target encoding.
  //    noconv:   The source and target characters have the same type and encoding, so no
  //              conversion was necessary.

  class directory_entry;
  
namespace path_traits {
 
  typedef std::codecvt<wchar_t, char, std::mbstate_t> codecvt_type;

  //  is_pathable type trait; allows disabling over-agressive class path member templates

  template <class T>
  struct is_pathable { static const bool value = false; };

  template<> struct is_pathable<char*>                  { static const bool value = true; };
  template<> struct is_pathable<const char*>            { static const bool value = true; };
  template<> struct is_pathable<wchar_t*>               { static const bool value = true; };
  template<> struct is_pathable<const wchar_t*>         { static const bool value = true; };
  template<> struct is_pathable<std::string>            { static const bool value = true; };
  template<> struct is_pathable<std::wstring>           { static const bool value = true; };
  template<> struct is_pathable<std::vector<char> >     { static const bool value = true; };
  template<> struct is_pathable<std::vector<wchar_t> >  { static const bool value = true; };
  template<> struct is_pathable<std::list<char> >       { static const bool value = true; };
  template<> struct is_pathable<std::list<wchar_t> >    { static const bool value = true; };
  template<> struct is_pathable<directory_entry>        { static const bool value = true; };

  //  Pathable empty

  template <class Container> inline
    // disable_if aids broken compilers (IBM, old GCC, etc.) and is harmless for
    // conforming compilers. Replace by plain "bool" at some future date (2012?) 
    typename boost::disable_if<boost::is_array<Container>, bool>::type
      empty(const Container & c)
        { return c.begin() == c.end(); }

  template <class T> inline
    bool empty(T * const & c_str)
  {
    BOOST_ASSERT(c_str);
    return !*c_str;
  }

  template <typename T, size_t N> inline
     bool empty(T (&x)[N])
       { return !x[0]; }

  // value types differ  ---------------------------------------------------------------//
  //
  //   A from_end argument of 0 is less efficient than a known end, so use only if needed
  
  BOOST_FILESYSTEM_DECL
  void convert(const char* from,
                const char* from_end,    // 0 for null terminated MBCS
                std::wstring & to,
                const codecvt_type& cvt);

  BOOST_FILESYSTEM_DECL
  void convert(const wchar_t* from,
                const wchar_t* from_end,  // 0 for null terminated MBCS
                std::string & to,
                const codecvt_type& cvt);

  inline 
  void convert(const char* from,
                std::wstring & to,
                const codecvt_type& cvt)
  {
    BOOST_ASSERT(from);
    convert(from, 0, to, cvt);
  }

  inline 
  void convert(const wchar_t* from,
                std::string & to,
                const codecvt_type& cvt)
  {
    BOOST_ASSERT(from);
    convert(from, 0, to, cvt);
  }

  // value types same  -----------------------------------------------------------------//

  // char

  inline 
  void convert(const char* from, const char* from_end, std::string & to,
    const codecvt_type&)
  {
    BOOST_ASSERT(from);
    BOOST_ASSERT(from_end);
    to.append(from, from_end);
  }

  inline 
  void convert(const char* from,
                std::string & to,
                const codecvt_type&)
  {
    BOOST_ASSERT(from);
    to += from;
  }

  // wchar_t

  inline 
  void convert(const wchar_t* from, const wchar_t* from_end, std::wstring & to,
    const codecvt_type&)
  {
    BOOST_ASSERT(from);
    BOOST_ASSERT(from_end);
    to.append(from, from_end);
  }

  inline 
  void convert(const wchar_t* from,
                std::wstring & to,
                const codecvt_type&)
  {
    BOOST_ASSERT(from);
    to += from;
  }

  //  Source dispatch  -----------------------------------------------------------------//

  //  contiguous containers
  template <class U> inline
    void dispatch(const std::string& c, U& to, const codecvt_type& cvt)
  {
    if (c.size())
      convert(&*c.begin(), &*c.begin() + c.size(), to, cvt);
  }
  template <class U> inline
    void dispatch(const std::wstring& c, U& to, const codecvt_type& cvt)
  {
    if (c.size())
      convert(&*c.begin(), &*c.begin() + c.size(), to, cvt);
  }
  template <class U> inline
    void dispatch(const std::vector<char>& c, U& to, const codecvt_type& cvt)
  {
    if (c.size())
      convert(&*c.begin(), &*c.begin() + c.size(), to, cvt);
  }
  template <class U> inline
    void dispatch(const std::vector<wchar_t>& c, U& to, const codecvt_type& cvt)
  {
    if (c.size())
      convert(&*c.begin(), &*c.begin() + c.size(), to, cvt);
  }

  //  non-contiguous containers
  template <class Container, class U> inline
    // disable_if aids broken compilers (IBM, old GCC, etc.) and is harmless for
    // conforming compilers. Replace by plain "void" at some future date (2012?) 
    typename boost::disable_if<boost::is_array<Container>, void>::type
      dispatch(const Container & c, U& to, const codecvt_type& cvt)
  {
    if (c.size())
    {
      std::basic_string<typename Container::value_type> s(c.begin(), c.end());
      convert(s.c_str(), s.c_str()+s.size(), to, cvt);
    }
  }

  //  c_str
  template <class T, class U> inline
  void dispatch(T * const & c_str, U& to, const codecvt_type& cvt)
  {
//    std::cout << "dispatch() const T *\n";
    BOOST_ASSERT(c_str);
    convert(c_str, to, cvt);
  }
  
  //  Note: there is no dispatch on C-style arrays because the array may
  //  contain a string smaller than the array size. 

  BOOST_FILESYSTEM_DECL
  void dispatch(const directory_entry & de,
#                ifdef BOOST_WINDOWS_API
                   std::wstring & to,
#                else   
                   std::string & to,
#                endif
                 const codecvt_type&);


}}} // namespace boost::filesystem::path_traits

#include <boost/config/abi_suffix.hpp> // pops abi_prefix.hpp pragmas

#endif  // BOOST_FILESYSTEM_PATH_TRAITS_HPP