[Emacs-diffs] Changes to emacs/src/textprop.c

[Miles Bader]

Index: emacs/src/textprop.c
diff -c emacs/src/textprop.c:1.123 emacs/src/textprop.c:1.124
*** emacs/src/textprop.c:1.123  Fri Jan 25 17:42:05 2002
--- emacs/src/textprop.c        Thu Mar 14 03:10:35 2002
***************
*** 1,5 ****
  /* Interface code for dealing with text properties.
!    Copyright (C) 1993, 1994, 1995, 1997, 1999, 2000, 2001
     Free Software Foundation, Inc.
  
  This file is part of GNU Emacs.
--- 1,5 ----
  /* Interface code for dealing with text properties.
!    Copyright (C) 1993, 1994, 1995, 1997, 1999, 2000, 2001, 2002
     Free Software Foundation, Inc.
  
  This file is part of GNU Emacs.
***************
*** 1554,1559 ****
--- 1554,1616 ----
      }
    return Qnil;
  }
+ 
+ 
+ /* Return the direction from which the text-property PROP would be
+    inherited by any new text inserted at POS: 1 if it would be
+    inherited from the char after POS, -1 if it would be inherited from
+    the char before POS, and 0 if from neither.  */
+ 
+ int
+ text_property_stickiness (prop, pos)
+      Lisp_Object prop;
+      Lisp_Object pos;
+ {
+   Lisp_Object prev_pos, front_sticky;
+   int is_rear_sticky = 1, is_front_sticky = 0; /* defaults */
+ 
+   if (XINT (pos) > BEGV)
+     /* Consider previous character.  */
+     {
+       Lisp_Object rear_non_sticky;
+ 
+       prev_pos = make_number (XINT (pos) - 1);
+       rear_non_sticky = Fget_text_property (prev_pos, Qrear_nonsticky, Qnil);
+ 
+       if (!NILP (CONSP (rear_non_sticky)
+                ? Fmemq (prop, rear_non_sticky)
+                : rear_non_sticky))
+       /* PROP is rear-non-sticky.  */
+       is_rear_sticky = 0;
+     }
+ 
+   /* Consider following character.  */
+   front_sticky = Fget_text_property (pos, Qfront_sticky, Qnil);
+ 
+   if (EQ (front_sticky, Qt)
+       || (CONSP (front_sticky)
+         && !NILP (Fmemq (prop, front_sticky))))
+     /* PROP is inherited from after.  */
+     is_front_sticky = 1;
+ 
+   /* Simple cases, where the properties are consistent.  */
+   if (is_rear_sticky && !is_front_sticky)
+     return -1;
+   else if (!is_rear_sticky && is_front_sticky)
+     return 1;
+   else if (!is_rear_sticky && !is_front_sticky)
+     return 0;
+ 
+   /* The stickiness properties are inconsistent, so we have to
+      disambiguate.  Basically, rear-sticky wins, _except_ if the
+      property that would be inherited has a value of nil, in which case
+      front-sticky wins.  */
+   if (XINT (pos) == BEGV || NILP (Fget_text_property (prev_pos, prop, Qnil)))
+     return 1;
+   else
+     return -1;
+ }
+ 
  
  /* I don't think this is the right interface to export; how often do you
     want to do something like this, other than when you're copying objects