IO#erase_line

static VALUE
console_erase_line(VALUE io, VALUE val)
{
    int mode = mode_in_range(val, 2, "line erase");
#ifdef _WIN32
    HANDLE h;
    rb_console_size_t ws;
    COORD *pos = &ws.dwCursorPosition;
    DWORD w;

    h = (HANDLE)rb_w32_get_osfhandle(GetWriteFD(io));
    if (!GetConsoleScreenBufferInfo(h, &ws)) {
        rb_syserr_fail(LAST_ERROR, 0);
    }
    w = winsize_col(&ws);
    switch (mode) {
      case 0:                   /* after cursor */
        w -= pos->X;
        break;
      case 1:                   /* before *and* cursor */
        w = pos->X + 1;
        pos->X = 0;
        break;
      case 2:                   /* entire line */
        pos->X = 0;
        break;
    }
    constat_clear(h, ws.wAttributes, w, *pos);
    return io;
#else
    rb_io_write(io, rb_sprintf(CSI "%dK", mode));
#endif
    return io;
}