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#include "unicode.hh"
#include "misc.hh"

using namespace lout::misc;

namespace lout {

namespace unicode {

static unsigned char alpha[0x500] = {
   // 0000-007F: C0 Controls and Basic Latin
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07,
   // 0080-00FF: C1 Controls and Latin-1 Supplement
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0xff, 0xff, 0x7f, 0xff, 0xff, 0xff, 0x7f, 0xff,
   // 0100-017F: Latin Extended-A
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   // 0180-024F: Latin Extended-B
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff,
   // 0250–02AF: IPA Extensions
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff,
   // 02B0–02FF: Spacing Modifier Letters
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00,
   // 0300–036F: Combining Diacritical Marks
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   // 0370–03FF: Greek and Coptic
   0xcf, 0x00, 0x40, 0x7d, 0xff, 0xff, 0xfb, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff,
   // 0400–04FF: Cyrillic
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0x03, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};

/**
 * Returns whether a given unicode character is an alphabetic character.
 */
bool isAlpha (int ch)
{
   return ch < 0x500 && (alpha[ch / 8] & (1 << (ch & 7)));
}

int decodeUtf8 (const char *s)
{
   if((s[0] & 0x80) == 0)
      return s[0];
   else if((s[0] & 0xe0) == 0xc0 && (s[1] & 0xc0) == 0x80)
      return ((s[0] & 0x1f) << 6) | (s[1] & 0x3f);
   else if((s[0] & 0xf0) == 0xe0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80)
      return ((s[0] & 0x0f) << 12) | ((s[1] & 0x3f) << 6)  | (s[2] & 0x3f);
   else if((s[0] & 0xf8) == 0xf0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80 && (s[3] & 0xc0) == 0x80)
      return ((s[0] & 0x0f) << 18) | ((s[1] & 0x3f) << 12)
         | ((s[2] & 0x3f) << 6) | (s[3] & 0x3f);
   else
      // Treat as ISO-8859-1 / ISO-8859-15 / Windows-1252
      return s[0];
}


int decodeUtf8 (const char *s, int len)
{
   if(len >= 1 && (s[0] & 0x80) == 0)
      return s[0];
   else if(len >= 2 && (s[0] & 0xe0) == 0xc0 && (s[1] & 0xc0) == 0x80)
      return ((s[0] & 0x1f) << 6) | (s[1] & 0x3f);
   else if(len >= 3 && (s[0] & 0xf0) == 0xe0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80)
      return ((s[0] & 0x0f) << 12) | ((s[1] & 0x3f) << 6)  | (s[2] & 0x3f);
   else if(len >= 4 && (s[0] & 0xf8) == 0xf0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80 && (s[3] & 0xc0) == 0x80)
      return ((s[0] & 0x0f) << 18) | ((s[1] & 0x3f) << 12)
         | ((s[2] & 0x3f) << 6) | (s[3] & 0x3f);
   else
      // Treat as ISO-8859-1 / ISO-8859-15 / Windows-1252
      return s[0];
}

const char *nextUtf8Char (const char *s)
{
   const char *r;

   if (s == NULL || s[0] == 0)
      r = NULL;
   else if((s[0] & 0x80) == 0)
      r = s + 1;
   else if((s[0] & 0xe0) == 0xc0 && (s[1] & 0xc0) == 0x80)
      r = s + 2;
   else if((s[0] & 0xf0) == 0xe0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80)
      r = s + 3;
   else if((s[0] & 0xf8) == 0xf0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80 && (s[3] & 0xc0) == 0x80)
      r = s + 4;
   else
      // invalid UTF-8 sequence: treat as one byte.
      r = s + 1;

   if (r && r[0] == 0)
      return NULL;
   else
      return r;
}

const char *nextUtf8Char (const char *s, int len)
{
   const char *r;

   if (s == NULL || len <= 0)
      r = NULL;
   else if(len >= 1 && (s[0] & 0x80) == 0)
      r = s + 1;
   else if(len >= 2 && (s[0] & 0xe0) == 0xc0 && (s[1] & 0xc0) == 0x80)
      r = s + 2;
   else if(len >= 3 && (s[0] & 0xf0) == 0xe0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80)
      r = s + 3;
   else if(len >= 4 && (s[0] & 0xf8) == 0xf0 && (s[1] & 0xc0) == 0x80
           && (s[2] & 0xc0) == 0x80 && (s[3] & 0xc0) == 0x80)
      r = s + 4;
   else
      // invalid UTF-8 sequence: treat as one byte.
      r = s + 1;

   if (r && r - s >= len)
      return NULL;
   else
      return r;
}

int numUtf8Chars (const char *s)
{
   int numUtf8 = 0;
   for (const char *r = s; r; r = nextUtf8Char (r))
      numUtf8++;
   return numUtf8;
}

int numUtf8Chars (const char *s, int len)
{
   int numUtf8 = 0;
   for (const char *r = s; len > 0 && r; r = nextUtf8Char (r, len))
      numUtf8++;
   return numUtf8;
}

} // namespace lout

} // namespace unicode