Make current-column, move-to-column and current-indentation

handle invisible chars (both text properties and overlays).
(skip_invisible): New function.
(Fmove_to_column): Use skip_invisible.  Get rid of `retry' label.
(compute_motion): Use skip_invisible.
(current_column_1): New function.
(current_column): Use current_column_1 if might have invisible text.

1 files changed, 200 insertions, 49 deletions

diff --git a/src/indent.c b/src/indent.c
index 452718cac77..a40006b9a5a 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -168,6 +168,82 @@ width_run_cache_on_off ()
 }
 
 
+/* Skip some invisible characters starting from POS.
+   This includes characters invisible because of text properties
+   and characters invisible because of overlays.
+
+   If position POS is followed by invisible characters,
+   skip some of them and return the position after them.
+   Otherwise return POS itself.
+
+   Set *NEXT_BOUNDARY_P to the next position at which
+   it will be necessary to call this function again.
+
+   Don't scan past TO, and don't set *NEXT_BOUNDARY_P
+   to a value greater than TO.
+
+   If WINDOW is non-nil, and this buffer is displayed in WINDOW,
+   take account of overlays that apply only in WINDOW.
+
+   We don't necessarily skip all the invisible characters after POS
+   because that could take a long time.  We skip a reasonable number
+   which can be skipped quickly.  If there might be more invisible
+   characters immediately following, then *NEXT_BOUNDARY_P
+   will equal the return value.  */
+
+static int
+skip_invisible (pos, next_boundary_p, to, window)
+     int pos;
+     int *next_boundary_p;
+     int to;
+     Lisp_Object window;
+{
+  Lisp_Object prop, position, end, overlay_limit, proplimit;
+  Lisp_Object buffer;
+
+  XSETFASTINT (position, pos);
+  XSETBUFFER (buffer, current_buffer);
+
+  /* Give faster response for overlay lookup near POS.  */
+  recenter_overlay_lists (current_buffer, pos);
+
+  /* We must not advance farther than the next overlay change.
+     The overlay change might change the invisible property;
+     or there might be overlay strings to be displayed there.  */
+  overlay_limit = Fnext_overlay_change (position);
+  /* As for text properties, this gives a lower bound
+     for where the invisible text property could change.  */
+  proplimit = Fnext_property_change (position, buffer, Qt);
+  if (XFASTINT (overlay_limit) < XFASTINT (proplimit))
+    proplimit = overlay_limit;
+  /* PROPLIMIT is now a lower bound for the next change
+     in invisible status.  If that is plenty far away,
+     use that lower bound.  */
+  if (XFASTINT (proplimit) > pos + 100 || XFASTINT (proplimit) >= to)
+    *next_boundary_p = XFASTINT (proplimit);
+  /* Otherwise, scan for the next `invisible' property change.  */
+  else
+    {
+      /* Don't scan terribly far.  */
+      XSETFASTINT (proplimit, min (pos + 100, to));
+      /* No matter what. don't go past next overlay change.  */
+      if (XFASTINT (overlay_limit) < XFASTINT (proplimit))
+        proplimit = overlay_limit;
+      end = Fnext_single_property_change (position, Qinvisible,
+                                          buffer, proplimit);
+      *next_boundary_p = XFASTINT (end);
+    }
+  /* if the `invisible' property is set, we can skip to
+     the next property change */
+  if (!NILP (window) && EQ (XWINDOW (window)->buffer, buffer))
+    prop = Fget_char_property (position, Qinvisible, window);
+  else
+    prop = Fget_char_property (position, Qinvisible, buffer);
+  if (TEXT_PROP_MEANS_INVISIBLE (prop))
+    return *next_boundary_p;
+  return pos;
+}
+
 DEFUN ("current-column", Fcurrent_column, Scurrent_column, 0, 0, 0,
   "Return the horizontal position of point.  Beginning of line is column 0.\n\
 This is calculated by adding together the widths of all the displayed\n\
@@ -209,6 +285,16 @@ current_column ()
       && MODIFF == last_known_column_modified)
     return last_known_column;
 
+  /* If the buffer has overlays or text properties,
+     use a more general algorithm.  */
+  if (BUF_INTERVALS (current_buffer)
+      || !NILP (current_buffer->overlays_before)
+      || !NILP (current_buffer->overlays_after))
+    return current_column_1 (point);
+
+  /* Scan backwards from point to the previous newline,
+     counting width.  Tab characters are the only complicated case.  */
+
   /* Make a pointer for decrementing through the chars before point.  */
   ptr = &FETCH_CHAR (point - 1) + 1;
   /* Make a pointer to where consecutive chars leave off,
@@ -274,6 +360,75 @@ current_column ()
   return col;
 }
 
+/* Return the column number of position POS
+   by scanning forward from the beginning of the line.
+   This function handles characters that are invisible
+   due to text properties or overlays.  */
+
+static int
+current_column_1 (pos)
+     int pos;
+{
+  register int tab_width = XINT (current_buffer->tab_width);
+  register int ctl_arrow = !NILP (current_buffer->ctl_arrow);
+  register struct Lisp_Char_Table *dp = buffer_display_table ();
+
+  /* Start the scan at the beginning of this line with column number 0.  */
+  register int col = 0;
+  int scan = find_next_newline (pos, -1);
+  int next_boundary = scan;
+
+  if (tab_width <= 0 || tab_width > 1000) tab_width = 8;
+
+  /* Scan forward to the target position.  */
+  while (scan < pos)
+    {
+      int c;
+
+      /* Occasionally we may need to skip invisible text.  */
+      while (scan == next_boundary)
+        {
+          /* This updates NEXT_BOUNDARY to the next place
+             where we might need to skip more invisible text.  */
+          scan = skip_invisible (scan, &next_boundary, pos, Qnil);
+          if (scan >= pos)
+            goto endloop;
+        }
+
+      c = FETCH_CHAR (scan);
+      if (dp != 0 && VECTORP (DISP_CHAR_VECTOR (dp, c)))
+        {
+          col += XVECTOR (DISP_CHAR_VECTOR (dp, c))->size;
+          scan++;
+          continue;
+        }
+      if (c == '\n')
+        break;
+      if (c == '\r' && EQ (current_buffer->selective_display, Qt))
+        break;
+      scan++;
+      if (c == '\t')
+        {
+          int prev_col = col;
+          col += tab_width;
+          col = col / tab_width * tab_width;
+        }
+      else if (ctl_arrow && (c < 040 || c == 0177))
+        col += 2;
+      else if (c < 040 || c >= 0177)
+        col += 4;
+      else
+        col++;
+    }
+ endloop:
+
+  last_known_column = col;
+  last_known_column_point = point;
+  last_known_column_modified = MODIFF;
+
+  return col;
+}
+
 /* Return the width in columns of the part of STRING from BEG to END.
    If BEG is nil, that stands for the beginning of STRING.
    If END is nil, that stands for the end of STRING.  */
@@ -421,20 +576,45 @@ position_indentation (pos)
   register int tab_width = XINT (current_buffer->tab_width);
   register unsigned char *p;
   register unsigned char *stop;
+  unsigned char *start;
+  int next_boundary = pos;
+  int ceiling = pos;
 
   if (tab_width <= 0 || tab_width > 1000) tab_width = 8;
 
-  stop = &FETCH_CHAR (BUFFER_CEILING_OF (pos)) + 1;
   p = &FETCH_CHAR (pos);
+  /* STOP records the value of P at which we will need
+     to think about the gap, or about invisible text,
+     or about the end of the buffer.  */
+  stop = p;
+  /* START records the starting value of P.  */
+  start = p;
   while (1)
     {
       while (p == stop)
         {
+          int stop_pos;
+
+          /* If we have updated P, set POS to match.
+             The first time we enter the loop, POS is already right.  */
+          if (p != start)
+            pos = PTR_CHAR_POS (p);
+          /* Consider the various reasons STOP might have been set here.  */
           if (pos == ZV)
             return column;
-          pos += p - &FETCH_CHAR (pos);
+          if (pos == next_boundary)
+            pos = skip_invisible (pos, &next_boundary, ZV, Qnil);
+          if (pos >= ceiling)
+            ceiling = BUFFER_CEILING_OF (pos) + 1;
+          /* Compute the next place we need to stop and think,
+             and set STOP accordingly.  */
+          stop_pos = min (ceiling, next_boundary);
+          /* The -1 and +1 arrange to point at the first byte of gap
+             (if STOP_POS is the position of the gap)
+             rather than at the data after the gap.  */
+             
+          stop = &FETCH_CHAR (stop_pos - 1) + 1;
           p = &FETCH_CHAR (pos);
-          stop = &FETCH_CHAR (BUFFER_CEILING_OF (pos)) + 1;
         }
       switch (*p++)
         {
@@ -461,7 +641,6 @@ indented_beyond_p (pos, column)
     pos = find_next_newline_no_quit (pos - 1, -1);
   return (position_indentation (pos) >= column);
 }
-
 
 DEFUN ("move-to-column", Fmove_to_column, Smove_to_column, 1, 2, "p",
   "Move point to column COLUMN in the current line.\n\
@@ -493,24 +672,34 @@ The return value is the current column.")
   int prev_col;
   int c;
 
+  int next_boundary;
+
   if (tab_width <= 0 || tab_width > 1000) tab_width = 8;
   CHECK_NATNUM (column, 0);
   goal = XINT (column);
 
- retry:
   pos = point;
   end = ZV;
+  next_boundary = pos;
 
   /* If we're starting past the desired column,
      back up to beginning of line and scan from there.  */
   if (col > goal)
     {
+      end = pos;
       pos = find_next_newline (pos, -1);
       col = 0;
     }
 
   while (col < goal && pos < end)
     {
+      while (pos == next_boundary)
+        {
+          pos = skip_invisible (pos, &next_boundary, end, Qnil);
+          if (pos >= end)
+            goto endloop;
+        }
+
       c = FETCH_CHAR (pos);
       if (dp != 0 && VECTORP (DISP_CHAR_VECTOR (dp, c)))
         {
@@ -536,6 +725,7 @@ The return value is the current column.")
       else
         col++;
     }
+ endloop:
 
   SET_PT (pos);
 
@@ -565,7 +755,6 @@ The return value is the current column.")
   XSETFASTINT (val, col);
   return val;
 }
-
 
 /* compute_motion: compute buffer posn given screen posn and vice versa */
 
@@ -713,49 +902,11 @@ compute_motion (from, fromvpos, fromhpos, did_motion, to, tovpos, tohpos, width,
           if (pos >= to)
             break;
 
-          {
-            Lisp_Object prop, position, end, limit, proplimit;
-
-            XSETFASTINT (position, pos);
-
-            /* Give faster response for overlay lookup near POS.  */
-            recenter_overlay_lists (current_buffer, pos);
-
-            /* We must not advance farther than the next overlay change.
-               The overlay change might change the invisible property;
-               or there might be overlay strings to be displayed there.  */
-            limit = Fnext_overlay_change (position);
-            /* As for text properties, this gives a lower bound
-               for where the invisible text property could change.  */
-            proplimit = Fnext_property_change (position, buffer, Qt);
-            if (XFASTINT (limit) < XFASTINT (proplimit))
-              proplimit = limit;
-            /* PROPLIMIT is now a lower bound for the next change
-               in invisible status.  If that is plenty far away,
-               use that lower bound.  */
-            if (XFASTINT (proplimit) > pos + 100 || XFASTINT (proplimit) >= to)
-              next_boundary = XFASTINT (proplimit);
-            /* Otherwise, scan for the next `invisible' property change.  */
-            else
-              {
-                /* Don't scan terribly far.  */
-                XSETFASTINT (proplimit, min (pos + 100, to));
-                /* No matter what. don't go past next overlay change.  */
-                if (XFASTINT (limit) < XFASTINT (proplimit))
-                  proplimit = limit;
-                end = Fnext_single_property_change (position, Qinvisible,
-                                                    buffer, proplimit);
-                next_boundary = XFASTINT (end);
-              }
-            /* if the `invisible' property is set, we can skip to
-               the next property change */
-            if (EQ (win->buffer, buffer))
-              prop = Fget_char_property (position, Qinvisible, window);
-            else
-              prop = Fget_char_property (position, Qinvisible, buffer);
-            if (TEXT_PROP_MEANS_INVISIBLE (prop))
-              pos = next_boundary;
-          }
+          /* Advance POS past invisible characters
+             (but not necessarily all that there are here),
+             and store in next_boundary the next position where
+             we need to call skip_invisible.  */
+          pos = skip_invisible (pos, &next_boundary, to, window);
         }
 
       /* Handle right margin.  */