Function re_update_line

extern/editline/src/refresh.c:500–964

#define	MIN_END_KEEP	4

private void
re_update_line(EditLine *el, Char *old, Char *new, int i)
{
	Char *o, *n, *p, c;
	Char *ofd, *ols, *oe, *nfd, *nls, *ne;
	Char *osb, *ose, *nsb, *nse;
	int fx, sx;
	size_t len;

	/*
         * find first diff
         */
	for (o = old, n = new; *o && (*o == *n); o++, n++)
		continue;
	ofd = o;
	nfd = n;

	/*
         * Find the end of both old and new
         */
	while (*o)
		o++;
	/*
         * Remove any trailing blanks off of the end, being careful not to
         * back up past the beginning.
         */
	while (ofd < o) {
		if (o[-1] != ' ')
			break;
		o--;
	}
	oe = o;
	*oe = '\0';

	while (*n)
		n++;

	/* remove blanks from end of new */
	while (nfd < n) {
		if (n[-1] != ' ')
			break;
		n--;
	}
	ne = n;
	*ne = '\0';

	/*
         * if no diff, continue to next line of redraw
         */
	if (*ofd == '\0' && *nfd == '\0') {
		ELRE_DEBUG(1, (__F, "no difference.\r\n"));
		return;
	}
	/*
         * find last same pointer
         */
	while ((o > ofd) && (n > nfd) && (*--o == *--n))
		continue;