string_coding.h

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// Copyright (c) 2006-2013, Andrey N. Sabelnikov, www.sabelnikov.net
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the Andrey N. Sabelnikov nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// 


#ifndef _STRING_CODING_H_
#define _STRING_CODING_H_

#include <string>

namespace epee
{
namespace string_encoding
{
    inline std::string convert_to_ansii(const std::wstring& str_from)
    {
        
        std::string res(str_from.begin(), str_from.end());
        return res;
        /*
        std::string result;
        std::locale loc;
        for(unsigned int i= 0; i < str_from.size(); ++i)
        {
            result += std::use_facet<std::ctype<wchar_t> >(loc).narrow(str_from[i]);
        }
        return result;
        */
        
        //return boost::lexical_cast<std::string>(str_from);
        /*
        std::string str_trgt;
        if(!str_from.size())
            return str_trgt;
        int cb = ::WideCharToMultiByte( code_page, 0, str_from.data(), (__int32)str_from.size(), 0, 0, 0, 0  );
        if(!cb)
            return str_trgt;
        str_trgt.resize(cb);
        ::WideCharToMultiByte(  code_page, 0, str_from.data(), (int)str_from.size(), 
                                    (char*)str_trgt.data(), (int)str_trgt.size(), 0, 0);
        return str_trgt;*/
    }

    inline std::string convert_to_ansii(const std::string& str_from)
    {
        return str_from;
    }

    inline std::wstring convert_to_unicode(const std::string& str_from)
    {
        std::wstring result;
        std::locale loc;
        for(unsigned int i= 0; i < str_from.size(); ++i)
        {
            result += std::use_facet<std::ctype<wchar_t> >(loc).widen(str_from[i]);
        }
        return result;
        
        //return boost::lexical_cast<std::wstring>(str_from);
        /*
        std::wstring str_trgt;
        if(!str_from.size())
            return str_trgt;

        int cb = ::MultiByteToWideChar( code_page, 0, str_from.data(), (int)str_from.size(), 0, 0 );
        if(!cb)
            return str_trgt;

        str_trgt.resize(cb);
        ::MultiByteToWideChar( code_page, 0, str_from.data(),(int)str_from.size(), 
                                (wchar_t*)str_trgt.data(),(int)str_trgt.size());
        return str_trgt;*/
    }
    inline std::wstring convert_to_unicode(const std::wstring& str_from)
    {
        return str_from;
    }

    template<class target_string>
    inline target_string convert_to_t(const std::wstring& str_from);
    
    template<>
    inline std::string convert_to_t<std::string>(const std::wstring& str_from)
    {
        return convert_to_ansii(str_from);
    }

    template<>
    inline std::wstring convert_to_t<std::wstring>(const std::wstring& str_from)
    {
        return str_from;
    }

    template<class target_string>
    inline target_string convert_to_t(const std::string& str_from);

    template<>
    inline std::string convert_to_t<std::string>(const std::string& str_from)
    {
        return str_from;
    }

    template<>
    inline std::wstring convert_to_t<std::wstring>(const std::string& str_from)
    {
        return convert_to_unicode(str_from);
    }

    inline 
    std::string& base64_chars()
    {

        static std::string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";

        return chars;

    }

    inline
    std::string base64_encode(unsigned char const* bytes_to_encode, size_t in_len) {
        std::string ret;
        int i = 0;
        int j = 0;
        unsigned char char_array_3[3];
        unsigned char char_array_4[4];

        while (in_len--) {
            char_array_3[i++] = *(bytes_to_encode++);
            if (i == 3) {
                char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
                char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
                char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
                char_array_4[3] = char_array_3[2] & 0x3f;

                for(i = 0; (i <4) ; i++)
                    ret += base64_chars()[char_array_4[i]];
                i = 0;
            }
        }

        if (i)
        {
            for(j = i; j < 3; j++)
                char_array_3[j] = '\0';

            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;

            for (j = 0; (j < i + 1); j++)
                ret += base64_chars()[char_array_4[j]];

            while((i++ < 3))
                ret += '=';

        }

        return ret;

    }

    inline
        std::string base64_encode(const std::string& str) 
    {
        return base64_encode((unsigned char const* )str.data(), str.size());
    }

    inline bool is_base64(unsigned char c) {
        return (isalnum(c) || (c == '+') || (c == '/'));
    }


    inline
    std::string base64_decode(std::string const& encoded_string) {
        size_t in_len = encoded_string.size();
        size_t i = 0;
        size_t j = 0;
        size_t in_ = 0;
        unsigned char char_array_4[4], char_array_3[3];
        std::string ret;

        while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
            char_array_4[i++] = encoded_string[in_]; in_++;
            if (i ==4) {
                for (i = 0; i <4; i++)
                    char_array_4[i] = (unsigned char)base64_chars().find(char_array_4[i]);

                char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
                char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
                char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

                for (i = 0; (i < 3); i++)
                    ret += char_array_3[i];
                i = 0;
            }
        }

        if (i) {
            for (j = i; j <4; j++)
                char_array_4[j] = 0;

            for (j = 0; j <4; j++)
                char_array_4[j] = (unsigned char)base64_chars().find(char_array_4[j]);

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
        }

        return ret;
    }

}
}

#endif //_STRING_CODING_H_