convert.hpp

//
//  Copyright (c) 2012 Artyom Beilis (Tonkikh)
//
//  Distributed under the Boost Software License, Version 1.0. (See
//  accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef BOOST_NOWIDE_CONVERT_H_INCLUDED
#define BOOST_NOWIDE_CONVERT_H_INCLUDED

#include <string>
#include <boost/locale/encoding_utf.hpp>

namespace boost {
namespace nowide {
    template<typename CharOut,typename CharIn>
    CharOut *basic_convert(CharOut *buffer,size_t buffer_size,CharIn const *source_begin,CharIn const *source_end)
    {
        CharOut *rv = buffer;
        if(buffer_size == 0)
            return 0;
        buffer_size --;
        while(source_begin!=source_end) {
            using namespace boost::locale::utf;
            code_point c = utf_traits<CharIn>::template decode<CharIn const *>(source_begin,source_end);
            if(c==illegal || c==incomplete) {
                rv = 0;
                break;
            }
            size_t width = utf_traits<CharOut>::width(c);
            if(buffer_size < width) {
                rv=0;
                break;
            }
            buffer = utf_traits<CharOut>::template encode<CharOut *>(c,buffer);
            buffer_size -= width;
        }
        *buffer++ = 0;
        return rv;
    }

    namespace details {
        //
        // wcslen defined only in C99... So we will not use it
        //
        template<typename Char>
        Char const *basic_strend(Char const *s)
        {
            while(*s)
                s++;
            return s;
        }
    }

    inline char *narrow(char *output,size_t output_size,wchar_t const *source)
    {
        return basic_convert(output,output_size,source,details::basic_strend(source));
    }
    inline char *narrow(char *output,size_t output_size,wchar_t const *begin,wchar_t const *end)
    {
        return basic_convert(output,output_size,begin,end);
    }
    inline wchar_t *widen(wchar_t *output,size_t output_size,char const *source)
    {
        return basic_convert(output,output_size,source,details::basic_strend(source));
    }
    inline wchar_t *widen(wchar_t *output,size_t output_size,char const *begin,char const *end)
    {
        return basic_convert(output,output_size,begin,end);
    }


    inline std::string narrow(wchar_t const *s)
    {
        return boost::locale::conv::utf_to_utf<char>(s);
    }
    inline std::wstring widen(char const *s)
    {
        return boost::locale::conv::utf_to_utf<wchar_t>(s);
    }
    inline std::string narrow(std::wstring const &s) 
    {
        return boost::locale::conv::utf_to_utf<char>(s);
    }
    inline std::wstring widen(std::string const &s) 
    {
        return boost::locale::conv::utf_to_utf<wchar_t>(s);
    }

} // nowide
} // namespace boost

#endif
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