+
+/* return the `current display line' of the cursor -- the number of lines to
+ move up to get to the first screen line of the current readline line. */
+int
+_rl_current_display_line ()
+{
+ int ret, nleft;
+
+ /* Find out whether or not there might be invisible characters in the
+ editing buffer. */
+ if (rl_display_prompt == rl_prompt)
+ nleft = _rl_last_c_pos - _rl_screenwidth - rl_visible_prompt_length;
+ else
+ nleft = _rl_last_c_pos - _rl_screenwidth;
+
+ if (nleft > 0)
+ ret = 1 + nleft / _rl_screenwidth;
+ else
+ ret = 0;
+
+ return ret;
+}
+
+#if defined (HANDLE_MULTIBYTE)
+/* Calculate the number of screen columns occupied by STR from START to END.
+ In the case of multibyte characters with stateful encoding, we have to
+ scan from the beginning of the string to take the state into account. */
+static int
+_rl_col_width (str, start, end)
+ char *str;
+ int start, end;
+{
+ wchar_t wc;
+ mbstate_t ps = {0};
+ int tmp, point, width, max;
+
+ if (end <= start)
+ return 0;
+
+ point = 0;
+ max = end;
+
+ while (point < start)
+ {
+ tmp = mbrlen (str + point, max, &ps);
+ if ((size_t)tmp == (size_t)-1 || (size_t)tmp == (size_t)-2)
+ {
+ /* In this case, the bytes are invalid or too short to compose a
+ multibyte character, so we assume that the first byte represents
+ a single character. */
+ point++;
+ max--;
+
+ /* Clear the state of the byte sequence, because in this case the
+ effect of mbstate is undefined. */
+ memset (&ps, 0, sizeof (mbstate_t));
+ }
+ else if (tmp == 0)
+ break; /* Found '\0' */
+ else
+ {
+ point += tmp;
+ max -= tmp;
+ }
+ }
+
+ /* If START is not a byte that starts a character, then POINT will be
+ greater than START. In this case, assume that (POINT - START) gives
+ a byte count that is the number of columns of difference. */
+ width = point - start;
+
+ while (point < end)
+ {
+ tmp = mbrtowc (&wc, str + point, max, &ps);
+ if ((size_t)tmp == (size_t)-1 || (size_t)tmp == (size_t)-2)
+ {
+ /* In this case, the bytes are invalid or too short to compose a
+ multibyte character, so we assume that the first byte represents
+ a single character. */
+ point++;
+ max--;
+
+ /* and assume that the byte occupies a single column. */
+ width++;
+
+ /* Clear the state of the byte sequence, because in this case the
+ effect of mbstate is undefined. */
+ memset (&ps, 0, sizeof (mbstate_t));
+ }
+ else if (tmp == 0)
+ break; /* Found '\0' */
+ else
+ {
+ point += tmp;
+ max -= tmp;
+ tmp = wcwidth(wc);
+ width += (tmp >= 0) ? tmp : 1;
+ }
+ }
+
+ width += point - end;
+
+ return width;
+}
+#endif /* HANDLE_MULTIBYTE */
+