[Emacs-diffs] Changes to emacs/lisp/font-core.el

[Alan Mackenzie]

Index: emacs/lisp/font-core.el
diff -u emacs/lisp/font-core.el:1.39 emacs/lisp/font-core.el:1.40
--- emacs/lisp/font-core.el:1.39        Mon Feb  6 14:33:33 2006
+++ emacs/lisp/font-core.el     Tue Mar 14 18:23:47 2006
@@ -83,6 +83,34 @@
 settings.  See the variable `font-lock-defaults', which takes precedence.")
 (make-obsolete-variable 'font-lock-defaults-alist 'font-lock-defaults)
 
+(defvar font-lock-extend-region-function nil
+  "A function that determines the region to fontify after a change.
+
+This buffer-local variable is either nil, or is a function that determines the
+region to fontify.  It is usually set by the major mode.  The currently active
+font-lock after-change function calls this function after each buffer change.
+
+The function is given three parameters, the standard BEG, END, and OLD-LEN
+from after-change-functions.  It should return either a cons of the beginning
+and end buffer positions \(in that order) of the region to fontify, or nil
+\(which directs the caller to fontify a default region).  This function need
+not preserve point or the match-data, but must preserve the current
+restriction.  The region it returns may start or end in the middle of a
+line.")
+(make-variable-buffer-local 'font-lock-extend-region-function)
+
+(defun font-lock-extend-region (beg end old-len)
+  "Determine the region to fontify after a buffer change.
+
+BEG END and OLD-LEN are the standard parameters from after-change-functions.
+The return value is either nil \(which directs the caller to chose the region
+itself), or a cons of the beginning and end \(in that order) of the region.
+The region returned may start or end in the middle of a line."
+  (if font-lock-extend-region-function
+      (save-match-data
+       (save-excursion
+         (funcall font-lock-extend-region-function beg end old-len)))))
+
 (defvar font-lock-function 'font-lock-default-function
   "A function which is called when `font-lock-mode' is toggled.
 It will be passed one argument, which is the current value of