Fix Emacs-lockup during fontification.

Fixes non-exiting loop in detection of square-parentasis regions.

Closes #17.

Author: josteink

csharp-mode.el

@@ -539,6 +539,20 @@ comment at the start of cc-engine.el for more info."
       rtn))
 
 
+(defun csharp-is-square-parentasis-block-p ()
+  "Attempts to safely assess if the current point is at the opening of
+a square parentasis block [ ... ]."
+  (let* ((start (point)) ;; variables used to hold our position, so that we know that
+	 (end))          ;; our code isn't stuck trying to look for a non-existant sexp.
+    (and (eq (char-after) 91) ;; open square
+	 (while (and (eq (char-after) 91)
+		     (not (eq start end)))
+	   (c-safe (c-forward-sexp 1))
+	   (setq end (point)))
+	 (eq (char-before) 93))) ;; close square
+  )
+
+
 
 ;; ==================================================================
 ;; end of csharp-mode utility and feature defuns
@@ -942,10 +956,7 @@ comment at the start of cc-engine.el for more info."
 
                                 (if (or
                                      (eq (char-after) ?{) ;; open curly
-                                     (and (eq (char-after) 91) ;; open square
-                                          (while (eq (char-after) 91)
-                                            (c-safe (c-forward-sexp 1)))
-                                          (eq (char-before) 93)) ;; close square
+                                     (csharp-is-square-parentasis-block-p)
                                      (and (eq (char-after) 40) ;; open paren
                                           (c-safe (c-forward-sexp 1) t)))