utf8_strings.cpp

#ifdef _WIN32
#pragma warning(disable: 4244)  // conversion from 'unsigned int' to '_Elem', possible loss of data
#endif
 
#include "html.h"
#include "utf8_strings.h"
 
 
litehtml::utf8_to_wchar::utf8_to_wchar(const char* val)
{
        m_utf8 = (const byte*) val;
        while (true)
        {
                ucode_t wch = get_char();
                if (!wch) break;
                m_str += wch;
        }
}
 
litehtml::ucode_t litehtml::utf8_to_wchar::get_char()
{
        ucode_t b1 = getb();
 
        if (!b1)
        {
                return 0;
        }
 
        // Determine whether we are dealing
        // with a one-, two-, three-, or four-
        // byte sequence.
        if ((b1 & 0x80) == 0)
        {
                // 1-byte sequence: 000000000xxxxxxx = 0xxxxxxx
                return b1;
        }
        else if ((b1 & 0xe0) == 0xc0)
        {
                // 2-byte sequence: 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx
                ucode_t r = (b1 & 0x1f) << 6;
                r |= get_next_utf8(getb());
                return r;
        }
        else if ((b1 & 0xf0) == 0xe0)
        {
                // 3-byte sequence: zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx
                ucode_t r = (b1 & 0x0f) << 12;
                r |= get_next_utf8(getb()) << 6;
                r |= get_next_utf8(getb());
                return r;
        }
        else if ((b1 & 0xf8) == 0xf0)
        {
                // 4-byte sequence: 11101110wwwwzzzzyy + 110111yyyyxxxxxx
                //     = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx
                // (uuuuu = wwww + 1)
                int b2 = get_next_utf8(getb());
                int b3 = get_next_utf8(getb());
                int b4 = get_next_utf8(getb());
                return ((b1 & 7) << 18) | ((b2 & 0x3f) << 12) |
                        ((b3 & 0x3f) << 6) | (b4 & 0x3f);
        }
 
        //bad start for UTF-8 multi-byte sequence
        return '?';
}
 
litehtml::wchar_to_utf8::wchar_to_utf8(const wchar_t* val)
{
        unsigned int code;
        for (int i = 0; val[i]; i++)
        {
                code = val[i];
                if (code <= 0x7F)
                {
                        m_str += (char)code;
                }
                else if (code <= 0x7FF)
                {
                        m_str += (code >> 6) + 192;
                        m_str += (code & 63) + 128;
                }
                else if (0xd800 <= code && code <= 0xdfff)
                {
                        //invalid block of utf8
                }
                else if (code <= 0xFFFF)
                {
                        m_str += (code >> 12) + 224;
                        m_str += ((code >> 6) & 63) + 128;
                        m_str += (code & 63) + 128;
                }
                else if (code <= 0x10FFFF)
                {
                        m_str += (code >> 18) + 240;
                        m_str += ((code >> 12) & 63) + 128;
                        m_str += ((code >> 6) & 63) + 128;
                        m_str += (code & 63) + 128;
                }
        }
}