utf8_codecvt.h

//
//  Copyright (c) 2015 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 BOOSTER_LOCALE_UTF8_CODECVT_HPP
#define BOOSTER_LOCALE_UTF8_CODECVT_HPP

#include <booster/locale/utf.h>
#include <booster/locale/generic_codecvt.h>
#include <booster/cstdint.h>
#include <locale>

namespace booster {
namespace locale {

template<typename CharType>
class utf8_codecvt : public generic_codecvt<CharType,utf8_codecvt<CharType> > 
{
public:
   
    struct state_type {};

    utf8_codecvt(size_t refs = 0) : generic_codecvt<CharType,utf8_codecvt<CharType> >(refs)
    {
    }

    static int max_encoding_length()
    {
        return 4;
    }

    static state_type initial_state(generic_codecvt_base::initial_convertion_state /* unused */)
    {
        return state_type();
    }
    static utf::code_point to_unicode(state_type &,char const *&begin,char const *end) 
    {
        char const *p=begin;

        utf::code_point c = utf::utf_traits<char>::decode(p,end);
        if(c!=utf::illegal && c!=utf::incomplete)
            begin = p;
        return c;
    }

    static utf::code_point from_unicode(state_type &,utf::code_point u,char *begin,char const *end) 
    {
        if(!utf::is_valid_codepoint(u))
            return utf::illegal;
        int width;
        if((width=utf::utf_traits<char>::width(u)) > end - begin)
            return utf::incomplete;
        utf::utf_traits<char>::encode(u,begin);
        return width;
    }
};

} // locale
} // namespace boost

#endif
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