CC Mode: Fontify "found types" which are recognized after being first scanned

This aims to fix the scenario where on jit-lock's first scan of a type, it is
not recognized as such, and only later does this happen.  The fontification of
such found types is now done by background scanning in short time slices
immediately after initialising the mode.

* lisp/progmodes/cc-engine.el (c-add-type-1): New function.
(c-add-type): Extract c-add-type-1 from it, and reformulate the mechanism for
protecting c-found-types from excessive partial identifiers.

* lisp/progmodes/cc-fonts.el (c-font-lock-complex-decl-prepare): Remove the
code which cleared c-found-types on fontification at BOB.
(c-find-types-background): New function, based on c-font-lock-declarations).
(c-types-finder-timer-func): New function.
(c-re-redisplay-timer): New variable.
(c-force-redisplay, c-fontify-new-found-type): New functions.

* lisp/progmodes/cc-mode.el (c-type-finder-timer): New variable.
(c-leave-cc-mode-mode): Nullify c-post-command-hook and c-type-finder-timer
when the last CC Mode buffer of a session is killed.
(c-type-finder-pos): New variable.
(c-basic-common-init): Initialize c-type-finder-pos and c-type-finder-timer.
(c-new-id-start, c-new-id-end, c-new-id-is-type): New variables.
(c-update-new-id): New function.
(c-post-command): New post command hook function, used for checking moving
away from partially typed identifiers, and making them full identifiers.
(c-before-change): Add code to clear c-found-types on a buffer change at BOB.
(c-after-change): Call c-update-new-id to keep track of partially typed
identifiers.

* doc/misc/cc-mode.texi (Found Types): New @section in the @Chapter Font
Locking.

* lisp/progmodes/cc-vars.el (c-type-finder-time-slot)
(c-type-finder-repeat-time, c-type-finder-chunk-size): New customizable
options.

1 files changed, 77 insertions, 4 deletions

diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index c9b7a95df60..80909380ebd 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -129,6 +129,10 @@
 ;   '
 (require 'cc-fonts) ;)
 
+(defvar c-type-finder-timer nil)
+;; The variable which holds the repeating idle timer which triggers off the
+;; background type finding search.
+
 ;; The following three really belong to cc-fonts.el, but they are required
 ;; even when cc-fonts.el hasn't been loaded (this happens in XEmacs when
 ;; font-lock-mode is nil).
@@ -179,6 +183,17 @@
   (when c-buffer-is-cc-mode
     (save-restriction
       (widen)
+      (let ((lst (buffer-list)))
+	(catch 'found
+	  (dolist (b lst)
+	    (if (and (not (eq b (current-buffer)))
+		     (with-current-buffer b
+		       c-buffer-is-cc-mode))
+		(throw 'found nil)))
+	  (remove-hook 'post-command-hook 'c-post-command)
+	  (and c-type-finder-timer
+	       (progn (cancel-timer c-type-finder-timer)
+		      (setq c-type-finder-timer nil)))))
       (c-save-buffer-state ()
 	(c-clear-char-properties (point-min) (point-max) 'category)
 	(c-clear-char-properties (point-min) (point-max) 'syntax-table)
@@ -574,6 +589,12 @@ preferably use the `c-mode-menu' language constant directly."
 ;; currently no such text property.
 (make-variable-buffer-local 'c-max-syn-tab-mkr)
 
+;; `c-type-finder-pos' is a marker marking the current place in a CC Mode
+;; buffer which is due to be searched next for "found types", or nil if the
+;; searching is complete.
+(defvar c-type-finder-pos nil)
+(make-variable-buffer-local 'c-type-finder-pos)
+
 (defun c-basic-common-init (mode default-style)
   "Initialize the syntax handling routines and the line breaking/filling code.
 Intended to be used by other packages that embed CC Mode.
@@ -745,6 +766,15 @@ that requires a literal mode spec at compile time."
   ;; would do since font-lock uses a(n implicit) depth of 0) so we don't need
   ;; c-after-font-lock-init.
   (add-hook 'after-change-functions 'c-after-change nil t)
+  (add-hook 'post-command-hook 'c-post-command)
+  (setq c-type-finder-pos
+	(save-restriction
+	  (widen)
+	  (move-marker (make-marker) (point-min))))
+  (or c-type-finder-timer
+      (setq c-type-finder-timer
+	    (run-at-time
+	     t c-type-finder-repeat-time #'c-types-finder-timer-func)))
   (when (boundp 'font-lock-extend-after-change-region-function)
     (set (make-local-variable 'font-lock-extend-after-change-region-function)
          'c-extend-after-change-region))) ; Currently (2009-05) used by all
@@ -1950,6 +1980,43 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
 	;; confused by already processed single quotes.
 	(narrow-to-region (point) (point-max))))))
 
+;; The next two variables record the bounds of an identifier currently being
+;; typed in.  These are used to prevent such a partial identifier being
+;; recorded as a found type by c-add-type.
+(defvar c-new-id-start nil)
+(make-variable-buffer-local 'c-new-id-start)
+(defvar c-new-id-end nil)
+(make-variable-buffer-local 'c-new-id-end)
+;; The next variable, when non-nil, records that the previous two variables
+;; define a type.
+(defvar c-new-id-is-type nil)
+(make-variable-buffer-local 'c-new-id-is-type)
+
+(defun c-update-new-id (end)
+  ;; Note the bounds of any identifier that END is in or just after, in
+  ;; `c-new-id-start' and `c-new-id-end'.  Otherwise set these variables to
+  ;; nil.
+  (save-excursion
+    (goto-char end)
+    (let ((id-beg (c-on-identifier)))
+      (setq c-new-id-start id-beg
+	    c-new-id-end (and id-beg
+			      (progn (c-end-of-current-token) (point)))))))
+
+
+(defun c-post-command ()
+  ;; If point was inside of a new identifier and no longer is, record that
+  ;; fact.
+  (when (and c-buffer-is-cc-mode
+	     c-new-id-start c-new-id-end
+	     (or (> (point) c-new-id-end)
+		 (< (point) c-new-id-start)))
+    (when c-new-id-is-type
+      (c-add-type-1 c-new-id-start c-new-id-end))
+    (setq c-new-id-start nil
+	  c-new-id-end nil
+	  c-new-id-is-type nil)))
+
 (defun c-before-change (beg end)
   ;; Function to be put on `before-change-functions'.  Primarily, this calls
   ;; the language dependent `c-get-state-before-change-functions'.  It is
@@ -1969,11 +2036,16 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
   (unless (c-called-from-text-property-change-p)
     (save-restriction
       (widen)
+      ;; Clear the list of found types if we make a change at the start of the
+      ;; buffer, to make it easier to get rid of misspelled types and
+      ;; variables that have gotten recognized as types in malformed code.
+      (when (eq beg (point-min))
+	(c-clear-found-types))
       (if c-just-done-before-change
-	  ;; We have two consecutive calls to `before-change-functions' without
-	  ;; an intervening `after-change-functions'.  An example of this is bug
-	  ;; #38691.  To protect CC Mode, assume that the entire buffer has
-	  ;; changed.
+	  ;; We have two consecutive calls to `before-change-functions'
+	  ;; without an intervening `after-change-functions'.  An example of
+	  ;; this is bug #38691.  To protect CC Mode, assume that the entire
+	  ;; buffer has changed.
 	  (setq beg (point-min)
 		end (point-max)
 		c-just-done-before-change 'whole-buffer)
@@ -2151,6 +2223,7 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
 						      c->-as-paren-syntax)
 		    (c-clear-char-property-with-value beg end 'syntax-table nil)))
 
+		(c-update-new-id end)
 		(c-trim-found-types beg end old-len) ; maybe we don't
 						     ; need all of these.
 		(c-invalidate-sws-region-after beg end old-len)