Re: [jbw@macs.hw.ac.uk: part of display property on before-string property is not displayed]

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

>>>>> On Fri, 12 Oct 2007 15:59:57 -0400, Chong Yidong <cyd@stupidchicken.com> said:

> I think your reasoning is correct, but instead of

>     if (!STRINGP (it->stack[it->sp - 1].string))

> could you do

>     if (BUFFERP (object))

> instead?

Thanks for the comment.  This is more concise.

>>>>> On Thu, 11 Oct 2007 16:29:41 +0900, YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp> said:

> I guess the reason to pretend as if the `display' property were not
> processed yet at line 4240 is to process overlay strings at the
> start position of the `display' property later.

On second thought, this is not strictly correct.  If there're multiple
display specs, `position' is reused among them.

  3838	      for (; CONSP (prop); prop = XCDR (prop))
  3839		{
  3840		  if (handle_single_display_spec (it, XCAR (prop), object,
  3841						  position, display_replaced_p))
  3842		    display_replaced_p = 1;

The patch below breaks the loop for multiple display specs if a
replacing spec is found in a display property of a string.  This might
be a bit ad hoc, but I think drastic changes should be avoided for
Emacs 22.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

Index: src/xdisp.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/xdisp.c,v
retrieving revision 1.1149.2.11
diff -c -p -r1.1149.2.11 xdisp.c
*** src/xdisp.c	9 Oct 2007 01:28:33 -0000	1.1149.2.11
--- src/xdisp.c	15 Oct 2007 08:10:21 -0000
*************** handle_display_prop (it)
*** 3839,3845 ****
  	{
  	  if (handle_single_display_spec (it, XCAR (prop), object,
  					  position, display_replaced_p))
! 	    display_replaced_p = 1;
  	}
      }
    else if (VECTORP (prop))
--- 3839,3851 ----
  	{
  	  if (handle_single_display_spec (it, XCAR (prop), object,
  					  position, display_replaced_p))
! 	    {
! 	      display_replaced_p = 1;
! 	      /* If some text in a string is replaced, `position' no
! 		 longer points to the position of `object'.  */
! 	      if (STRINGP (object))
! 		break;
! 	    }
  	}
      }
    else if (VECTORP (prop))
*************** handle_display_prop (it)
*** 3848,3854 ****
        for (i = 0; i < ASIZE (prop); ++i)
  	if (handle_single_display_spec (it, AREF (prop, i), object,
  					position, display_replaced_p))
! 	  display_replaced_p = 1;
      }
    else
      {
--- 3854,3866 ----
        for (i = 0; i < ASIZE (prop); ++i)
  	if (handle_single_display_spec (it, AREF (prop, i), object,
  					position, display_replaced_p))
! 	  {
! 	    display_replaced_p = 1;
! 	    /* If some text in a string is replaced, `position' no
! 	       longer points to the position of `object'.  */
! 	    if (STRINGP (object))
! 	      break;
! 	  }
      }
    else
      {
*************** handle_single_display_spec (it, spec, ob
*** 4237,4249 ****
  	  /* Say that we haven't consumed the characters with
  	     `display' property yet.  The call to pop_it in
  	     set_iterator_to_next will clean this up.  */
! 	  *position = start_pos;
  	}
        else if (CONSP (value) && EQ (XCAR (value), Qspace))
  	{
  	  it->method = GET_FROM_STRETCH;
  	  it->object = value;
! 	  *position = it->position = start_pos;
  	}
  #ifdef HAVE_WINDOW_SYSTEM
        else
--- 4249,4264 ----
  	  /* Say that we haven't consumed the characters with
  	     `display' property yet.  The call to pop_it in
  	     set_iterator_to_next will clean this up.  */
! 	  if (BUFFERP (object))
! 	    it->current.pos = start_pos;
  	}
        else if (CONSP (value) && EQ (XCAR (value), Qspace))
  	{
  	  it->method = GET_FROM_STRETCH;
  	  it->object = value;
! 	  it->position = start_pos;
! 	  if (BUFFERP (object))
! 	    it->current.pos = start_pos;
  	}
  #ifdef HAVE_WINDOW_SYSTEM
        else
*************** handle_single_display_spec (it, spec, ob
*** 4257,4263 ****
  	  /* Say that we haven't consumed the characters with
  	     `display' property yet.  The call to pop_it in
  	     set_iterator_to_next will clean this up.  */
! 	  *position = start_pos;
  	}
  #endif /* HAVE_WINDOW_SYSTEM */
  
--- 4272,4279 ----
  	  /* Say that we haven't consumed the characters with
  	     `display' property yet.  The call to pop_it in
  	     set_iterator_to_next will clean this up.  */
! 	  if (BUFFERP (object))
! 	    it->current.pos = start_pos;
  	}
  #endif /* HAVE_WINDOW_SYSTEM */