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  1. #include <iostream>
  2. #include <string>
  3. #include <vector>
  4.  
  5. #include <boost/locale.hpp>
  6.  
  7. namespace yekneb
  8. {
  9.  
  10. namespace detail
  11. {
  12. namespace string_cast
  13. {
  14.  
  15. inline bool IsUTF8(const std::locale &loc)
  16. {
  17.     std::string locName = loc.name();
  18.     if (! locName.empty() && std::string::npos != locName.find("UTF-8"))
  19.     {
  20.         return true;
  21.     }
  22.     return false;
  23. }
  24.  
  25. inline std::string w2s(const std::wstring& ws, const std::locale& loc)
  26. {
  27.     typedef std::codecvt<wchar_t, char, std::mbstate_t> converter_type;
  28.     typedef std::ctype<wchar_t> wchar_facet;
  29.     std::string return_value;
  30.     if (ws.empty())
  31.     {
  32.         return "";
  33.     }
  34.     if (IsUTF8(loc))
  35.     {
  36.         return_value = boost::locale::conv::utf_to_utf<char>(ws);
  37.         if (! return_value.empty())
  38.         {
  39.             return return_value;
  40.         }
  41.     }
  42.     const wchar_t* from = ws.c_str();
  43.     size_t len = ws.length();
  44.     size_t converterMaxLength = 6;
  45.     size_t vectorSize = ((len + 6) * converterMaxLength);
  46.     if (std::has_facet<converter_type>(loc))
  47.     {
  48.         const converter_type& converter = std::use_facet<converter_type>(loc);
  49.         if (converter.always_noconv())
  50.         {
  51.             converterMaxLength = converter.max_length();
  52.             if (converterMaxLength != 6)
  53.             {
  54.                 vectorSize = ((len + 6) * converterMaxLength);
  55.             }
  56.             std::mbstate_t state;
  57.             const wchar_t* from_next = nullptr;
  58.             std::vector<char> to(vectorSize, 0);
  59.             std::vector<char>::pointer toPtr = to.data();
  60.             std::vector<char>::pointer to_next = nullptr;
  61.             const converter_type::result result = converter.out(
  62.                 state, from, from + len, from_next,
  63.                 toPtr, toPtr + vectorSize, to_next);
  64.             if (
  65.               (converter_type::ok == result || converter_type::noconv == result)
  66.               && 0 != toPtr[0]
  67.               )
  68.             {
  69.               return_value.assign(toPtr, to_next);
  70.             }
  71.         }
  72.     }
  73.     if (return_value.empty() && std::has_facet<wchar_facet>(loc))
  74.     {
  75.         std::vector<char> to(vectorSize, 0);
  76.         std::vector<char>::pointer toPtr = to.data();
  77.         const wchar_facet& facet = std::use_facet<wchar_facet>(loc);
  78.         if (facet.narrow(from, from + len, '?', toPtr) != 0)
  79.         {
  80.             return_value = toPtr;
  81.         }
  82.     }
  83.     return return_value;
  84. }
  85.  
  86. inline std::wstring s2w(const std::string& s, const std::locale& loc)
  87. {
  88.     typedef std::ctype<wchar_t> wchar_facet;
  89.     std::wstring return_value;
  90.     if (s.empty())
  91.     {
  92.         return L"";
  93.     }
  94.     if (std::has_facet<wchar_facet>(loc))
  95.     {
  96.         std::vector<wchar_t> to(s.size() + 2, 0);
  97.         std::vector<wchar_t>::pointer toPtr = to.data();
  98.         const wchar_facet& facet = std::use_facet<wchar_facet>(loc);
  99.         if (facet.widen(s.c_str(), s.c_str() + s.size(), toPtr) != 0)
  100.         {
  101.             return_value = to.data();
  102.         }
  103.     }
  104.     return return_value;
  105. }
  106.  
  107. }
  108. }
  109.  
  110. template<typename Target, typename Source>
  111. inline Target string_cast(const Source& source)
  112. {
  113.     return source;
  114. }
  115.  
  116. template<>
  117. inline std::wstring string_cast(const std::string& source)
  118. {
  119.     std::locale loc;
  120.     return ::yekneb::detail::string_cast::s2w(source, loc);
  121. }
  122.  
  123. template<>
  124. inline std::string string_cast(const std::wstring& source)
  125. {
  126.     std::locale loc;
  127.     return ::yekneb::detail::string_cast::w2s(source, loc);
  128. }
  129.  
  130. }
  131.  
  132. int main()
  133. {
  134.     std::string s1("Buenos días.");
  135.     std::wstring ws1 = yekneb::string_cast<std::wstring>(s1);
  136.     std::wcout << ws1 << L"\n";
  137.  
  138.     std::wstring ws2(L"Buenos días.");
  139.     std::string s2 = yekneb::string_cast<std::string>(ws2);
  140.     std::cout << s1 << "\n";
  141.  
  142.     return 0;
  143. }
  144.  
Success #stdin #stdout 0s 15240KB
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Standard input is empty
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Buenos d?
https://ideone.com/Cpffei
Cross Platform Conversion Between string and wstring
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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