(display_mode_element): New arg RISKY.

Disregard text props found or specified within a variable
that isn't marked risky-local-variable.
(Qrisky_local_variable): New variable.
(syms_of_xdisp): Init and staticpro it.

diff --git a/src/xdisp.c b/src/xdisp.c
index 224f495cb5ec31f57fe3841a9d27fbafda0e7e46..9dd35bae58f80024dcda3768d04b3f9365765911 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -226,6 +226,8 @@ Lisp_Object Qgrow_only;
 Lisp_Object Qinhibit_eval_during_redisplay;
 Lisp_Object Qbuffer_position, Qposition, Qobject;
 
+Lisp_Object Qrisky_local_variable;
+
 /* Holds the list (error).  */
 Lisp_Object list_of_error;
 
@@ -760,7 +762,7 @@ static int try_window_id P_ ((struct window *));
 static int display_line P_ ((struct it *));
 static int display_mode_lines P_ ((struct window *));
 static int display_mode_line P_ ((struct window *, enum face_id, Lisp_Object));
-static int display_mode_element P_ ((struct it *, int, int, int, Lisp_Object, Lisp_Object));
+static int display_mode_element P_ ((struct it *, int, int, int, Lisp_Object, Lisp_Object, int));
 static char *decode_mode_spec P_ ((struct window *, int, int, int, int *));
 static void display_menu_bar P_ ((struct window *));
 static int display_count_lines P_ ((int, int, int, int, int *));
@@ -4945,17 +4947,17 @@ next_element_from_composition (it)
 /* Move iterator IT to a specified buffer or X position within one
    line on the display without producing glyphs.
 
-   Begin to skip at IT's current position.  Skip to TO_CHARPOS or TO_X
-   whichever is reached first.
-
-   TO_CHARPOS <= 0 means no TO_CHARPOS is specified.
+   OP should be a bit mask including some or all of these bits:
+    MOVE_TO_X: Stop on reaching x-position TO_X.
+    MOVE_TO_POS: Stop on reaching buffer or string position TO_CHARPOS.
+   Regardless of OP's value, stop in reaching the end of the display line.
 
-   TO_X < 0 means that no TO_X is specified.  TO_X is normally a value
-   0 <= TO_X <= IT->last_visible_x.  This means in particular, that
-   TO_X includes the amount by which a window is horizontally
-   scrolled.
+   TO_X is normally a value 0 <= TO_X <= IT->last_visible_x.
+   This means, in particular, that TO_X includes window's horizontal
+   scroll amount.
 
-   Value is
+   The return value has several possible values that
+   say what condition caused the scan to stop:
 
    MOVE_POS_MATCH_OR_ZV
      - when TO_POS or ZV was reached.
@@ -7282,7 +7284,7 @@ x_consider_frame_title (frame)
       frame_title_ptr = frame_title_buf;
       init_iterator (&it, XWINDOW (f->selected_window), -1, -1,
                     NULL, DEFAULT_FACE_ID);
-      display_mode_element (&it, 0, -1, -1, fmt, Qnil);
+      display_mode_element (&it, 0, -1, -1, fmt, Qnil, 0);
       len = frame_title_ptr - frame_title_buf;
       frame_title_ptr = NULL;
       set_buffer_internal_1 (obuf);
@@ -13578,7 +13580,7 @@ display_mode_line (w, face_id, format)
      kboard-local variables in the mode_line_format will get the right
      values.  */
   push_frame_kboard (it.f);
-  display_mode_element (&it, 0, 0, 0, format, Qnil);
+  display_mode_element (&it, 0, 0, 0, format, Qnil, 0);
   pop_frame_kboard ();
 
   /* Fill up with spaces.  */
@@ -13621,14 +13623,20 @@ Lisp_Object mode_line_proptrans_alist;
    characters to display from ELT's representation.  See
    display_string for details.
 
-   Returns the hpos of the end of the text generated by ELT.  */
+   Returns the hpos of the end of the text generated by ELT.
+
+   PROPS is a property list to add to any string we encounter.
+
+   If RISKY is nonzero, remove (disregard) any properties in any string 
+   we encounter, and ignore :eval and :propertize.  */
 
 static int
-display_mode_element (it, depth, field_width, precision, elt, props)
+display_mode_element (it, depth, field_width, precision, elt, props, risky)
      struct it *it;
      int depth;
      int field_width, precision;
      Lisp_Object elt, props;
+     int risky;
 {
   int n = 0, field, prec;
   int literal = 0;
@@ -13647,15 +13655,16 @@ display_mode_element (it, depth, field_width, precision, elt, props)
        unsigned char c;
        unsigned char *this, *lisp_string;
 
-       if (!NILP (props))
+       if (!NILP (props) || risky)
          {
            Lisp_Object oprops, aelt;
            oprops = Ftext_properties_at (make_number (0), elt);
-           if (NILP (Fequal (props, oprops)))
+
+           if (NILP (Fequal (props, oprops)) || risky)
              {
                /* If the starting string has properties,
                   merge the specified ones onto the existing ones.  */
-               if (! NILP (oprops))
+               if (! NILP (oprops) && !risky)
                  {
                    Lisp_Object tem;
 
@@ -13752,7 +13761,8 @@ display_mode_element (it, depth, field_width, precision, elt, props)
                
                if (c == 'M')
                  n += display_mode_element (it, depth, field, prec,
-                                            Vglobal_mode_string, props);
+                                            Vglobal_mode_string, props,
+                                            risky);
                else if (c != 0)
                  {
                    int multibyte;
@@ -13813,6 +13823,12 @@ display_mode_element (it, depth, field_width, precision, elt, props)
         literally.  */
       {
        register Lisp_Object tem;
+
+       /* If the variable is not marked as risky to set
+          then its contents are risky to use.  */
+       if (NILP (Fget (elt, Qrisky_local_variable)))
+         risky = 1;
+
        tem = Fboundp (elt);
        if (!NILP (tem))
          {
@@ -13851,24 +13867,30 @@ display_mode_element (it, depth, field_width, precision, elt, props)
            /* An element of the form (:eval FORM) means evaluate FORM
               and use the result as mode line elements.  */
 
+           if (risky)
+             break;
+
            if (CONSP (XCDR (elt)))
              {
                Lisp_Object spec;
                spec = safe_eval (XCAR (XCDR (elt)));
                n += display_mode_element (it, depth, field_width - n,
-                                          precision - n, spec, props);
+                                          precision - n, spec, props,
+                                          risky);
              }
          }
        else if (EQ (car, QCpropertize))
          {
+           /* An element of the form (:propertize ELT PROPS...)
+              means display ELT but applying properties PROPS.  */
+
+           if (risky)
+             break;
+
            if (CONSP (XCDR (elt)))
-             {
-               /* An element of the form (:propertize ELT PROPS...)
-                  means display ELT but applying properties PROPS.  */
-               n += display_mode_element (it, depth, field_width - n,
-                                          precision - n, XCAR (XCDR (elt)),
-                                          XCDR (XCDR (elt)));
-             }
+             n += display_mode_element (it, depth, field_width - n,
+                                        precision - n, XCAR (XCDR (elt)),
+                                        XCDR (XCDR (elt)), risky);
          }
        else if (SYMBOLP (car))
          {
@@ -13933,7 +13955,8 @@ display_mode_element (it, depth, field_width, precision, elt, props)
                   && (precision <= 0 || n < precision))
              {
                n += display_mode_element (it, depth, field_width - n,
-                                          precision - n, XCAR (elt), props);
+                                          precision - n, XCAR (elt),
+                                          props, risky);
                elt = XCDR (elt);
              }
          }
@@ -14922,6 +14945,8 @@ syms_of_xdisp ()
   staticpro (&Qbuffer_position);
   Qobject = intern ("object");
   staticpro (&Qobject);
+  Qrisky_local_variable = intern ("risky-local-variable");
+  staticpro (&Qrisky_local_variable);
 
   list_of_error = Fcons (intern ("error"), Qnil);
   staticpro (&list_of_error);