sys/libutf/runewidth-14.0.0.c


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#include <u.h>
#include <libutf.h>

static
rune*
rangesearch(rune c, rune *t, int n, int ne)
{
   rune *p;
   int m;
   while(n > 1) {
   m = n >> 1;
   p = t + m*ne;
   if(c >= p[0]){
       t = p;
       n = n-m;
   }else
       n = m;
   }
   if(n && c >= t[0])
       return t;
   return 0;
}

static rune width0_range[] = {
	0x2028, 0x2029,
};

static int
iswidth0(rune c)
{
    rune *p;

   p = rangesearch(c, width0_range, arrlen(width0_range)/2, 2);
   if(p && c >= p[0] && c <= p[1])
       return 1;
   return 0;
}

static rune width1_single[] = {
	0x00ad,
};

static int
iswidth1(rune c)
{
    rune *p;

   p = rangesearch(c, width1_single, arrlen(width1_single), 1);
   if(p && c == p[0])
       return 1;
   return 0;
}

static int
iswidth2(rune c)
{
    rune *p;

   return 0;
}


int
utf8·runewidth(rune c)
{
   if(iswidth1(c))
       return 1;
   if(iswidth2(c))
       return 2;
   return 0;
}