Prevent Emacs fontification failure w/ lots of classes - Fixes #248

What I've done to fix this:

- add a sclang-class-list variable in sclang-language.el, which is a
  list of all the classes known to sclang. this is populated when
  sclang starts.
- update sclang-font-lock-class-keyword-matcher in
  sclang-mode.el. since the sclang-class-name-regexp now will match
  all words that start with a capital letter (see next bullet point
  for that change), this function had to be updated to check to make
  sure that the word starting with a capital letter is in the list of
  classes. if it is, then we know it's a class and it gets
  highlighted. if it's not, then it's just something the user typed
  with a capital letter, so we don't highlight it.
- update sclang-update-font-lock in sclang-mode.el. instead of
  generating a huge regexp from a list of all the classes in
  SuperCollider, just run the normal fontification from that
  function. this avoids making the regexp too big and thus prevents
  fontification from failing.

el/sclang-language.el

@@ -207,6 +207,9 @@ low-resource systems."
 (defvar sclang-symbol-table nil
   "List of all defined symbols.")
 
+(defvar sclang-class-list nil
+  "List of all defined classes.")
+
 (defvar sclang-symbol-history nil
   "List of recent symbols read from the minibuffer.")
 

el/sclang-mode.el

@@ -244,10 +244,20 @@
 	 'font-lock-comment-face)))
 
 (defun sclang-font-lock-class-keyword-matcher (limit)
-  (let ((regexp (or sclang-font-lock-class-keywords
-		    (concat "\\<" sclang-class-name-regexp "\\>")))
-	(case-fold-search nil))
-    (re-search-forward regexp limit t)))
+  (let ((regexp (concat "\\<" sclang-class-name-regexp "\\>"))
+        (case-fold-search nil)
+        (continue t)
+        (res nil))
+    (while continue
+      (setq res (re-search-forward regexp limit t))
+      (if (or (null res) (null sclang-class-list))
+          (setq continue nil)
+        (let ((thing (thing-at-point 'word)))
+          (if (null thing)
+              (setq res nil continue nil)
+            (when (position (substring-no-properties thing) sclang-class-list :test 'equal)
+              (setq continue nil))))))
+    res))
 
 (defun sclang-set-font-lock-keywords ()
   (setq
@@ -302,17 +312,6 @@
 
 (defun sclang-update-font-lock ()
   "Update font-lock information in all sclang-mode buffers."
-  (setq sclang-font-lock-class-keywords
-	(and sclang-symbol-table
-	     (let* ((list (remove-if
-			   (lambda (x) (or (not (sclang-class-name-p x))
-					   (sclang-string-match "^Meta_" x)))
-			   sclang-symbol-table))
-		    ;; need to set this for large numbers of classes
-		    (max-specpdl-size (* (length list) 2)))
-	       (condition-case nil
-		   (concat "\\<\\(?:Meta_\\)?\\(?:" (regexp-opt list) "\\)\\>")
-		 (error nil)))))
   ;; too expensive
   ;;   (dolist (buffer (buffer-list))
   ;;     (with-current-buffer buffer