Bug fix for hi-lock mode.

[David Koppelman]

The following patch fixes hi-lock, a minor mode I wrote, which was
broken some time ago due to changes in font-lock behavior.

Problems were due to font-lock-mode turning off and back on again,
that would turn off hi-lock mode. Now, turning off font lock does not
turn off hi-lock. Another problem was due to hi-lock adding keywords
when font lock mode was on (font-lock-mode non-nil) but
font-lock-keywords was nil, that would clobber non-font-lock
highlighting (Bug 635). Now hi-lock uses font-lock-fontified to decide
whether to add keywords to font lock. (If font-lock-fontified is nil
hi-lock will apply its own overlays for highlighting.)

I don't like using font-lock-fontified to determine whether font lock
is active because it's more of an internal font-lock
variable. However, it's the best solution I can come up with at the
moment (and the existing hi-lock code had been using
font-lock-fontified for some time).

Here is a change log entry followed by a patch. Could someone
check this in if it's suitable.

2010-10-05  David Koppelman  <address@hidden>

        * hi-lock.el (hi-lock-font-lock-hook): Check font-lock-fontified
        instead of font-lock-mode before adding keywords. Removed
        hi-lock-mode off code. Removed inhibit hack.
        (hi-lock-set-pattern): Only add keywords if font-lock-fontified
        non-nil; removed hook inhibit hack.

=== modified file 'lisp/hi-lock.el'
--- lisp/hi-lock.el     2010-01-13 08:35:10 +0000
+++ lisp/hi-lock.el     2010-10-05 14:18:04 +0000
@@ -564,23 +564,15 @@ not suitable."
            'face-name-history
           (cdr hi-lock-face-defaults))))
 
-(defvar hi-lock--inhibit-font-lock-hook nil
-  "Inhibit the action of `hi-lock-font-lock-hook'.
-This is used by `hi-lock-set-pattern'.")
-
 (defun hi-lock-set-pattern (regexp face)
   "Highlight REGEXP with face FACE."
-  (let ((pattern (list regexp (list 0 (list 'quote face) t)))
-       ;; The call to `font-lock-add-keywords' below might disable
-       ;; and re-enable font-lock mode.  If so, we don't want
-       ;; `hi-lock-font-lock-hook' to run.  This can be removed once
-       ;; Bug#635 is fixed. -- cyd
-       (hi-lock--inhibit-font-lock-hook t))
+  (let ((pattern (list regexp (list 0 (list 'quote face) t))))
     (unless (member pattern hi-lock-interactive-patterns)
-      (font-lock-add-keywords nil (list pattern) t)
       (push pattern hi-lock-interactive-patterns)
       (if font-lock-fontified
-          (font-lock-fontify-buffer)
+          (progn 
+            (font-lock-add-keywords nil (list pattern) t)
+            (font-lock-fontify-buffer))
         (let* ((serial (hi-lock-string-serialize regexp))
                (range-min (- (point) (/ hi-lock-highlight-range 2)))
                (range-max (+ (point) (/ hi-lock-highlight-range 2)))
@@ -641,12 +633,9 @@ This is used by `hi-lock-set-pattern'.")
 
 (defun hi-lock-font-lock-hook ()
   "Add hi-lock patterns to font-lock's."
-  (unless hi-lock--inhibit-font-lock-hook
-    (if font-lock-mode
-       (progn
+  (when font-lock-fontified
          (font-lock-add-keywords nil hi-lock-file-patterns t)
-         (font-lock-add-keywords nil hi-lock-interactive-patterns t))
-      (hi-lock-mode -1))))
+    (font-lock-add-keywords nil hi-lock-interactive-patterns t)))
 
 (defvar hi-lock-string-serialize-hash
   (make-hash-table :test 'equal)