]> code.delx.au - gnu-emacs-elpa/blobdiff - context-coloring.el
Add define-deftest macro.
[gnu-emacs-elpa] / context-coloring.el
index 3a57b3f1d5de5f0087a646b024bf47ba3898e053..cb74ee74e8387cf7db8366b656b21d9159439267 100644 (file)
@@ -3,7 +3,7 @@
 ;; Copyright (C) 2014-2015  Free Software Foundation, Inc.
 
 ;; Author: Jackson Ray Hamilton <jackson@jacksonrayhamilton.com>
-;; Version: 6.2.1
+;; Version: 6.3.0
 ;; Keywords: convenience faces tools
 ;; Package-Requires: ((emacs "24") (js2-mode "20150126"))
 ;; URL: https://github.com/jacksonrayhamilton/context-coloring
 
 ;; By default, comments and strings are still highlighted syntactically.
 
-;; To use with js2-mode, add the following to your init file:
-
-;; (require 'context-coloring)
-;; (add-hook 'js2-mode-hook 'context-coloring-mode)
-
-;; To use with js-mode or js3-mode, install Node.js 0.10+ and the scopifier
-;; executable:
-
-;; $ npm install -g scopifier
-
 ;;; Code:
 
 (require 'js2-mode)
 
 
-;;; Local variables
-
-(defvar-local context-coloring-buffer nil
-  "Reference to this buffer (for timers).")
-
-
 ;;; Utilities
 
 (defun context-coloring-join (strings delimiter)
@@ -172,29 +156,29 @@ the END point (exclusive) with the face corresponding to LEVEL."
   "Tell `font-lock' to color a string but not a comment."
   (if (nth 3 state) font-lock-string-face nil))
 
-(defsubst context-coloring-maybe-colorize-comments-and-strings ()
+(defsubst context-coloring-maybe-colorize-comments-and-strings (&optional min max)
   "Color the current buffer's comments and strings if
 `context-coloring-comments-and-strings' is non-nil."
   (when (or context-coloring-comments-and-strings
             context-coloring-syntactic-comments
             context-coloring-syntactic-strings)
-    (let ((old-function font-lock-syntactic-face-function)
-          saved-function-p)
-      (cond
-       ((and context-coloring-syntactic-comments
-             (not context-coloring-syntactic-strings))
-        (setq font-lock-syntactic-face-function
-              'context-coloring-font-lock-syntactic-comment-function)
-        (setq saved-function-p t))
-       ((and context-coloring-syntactic-strings
-             (not context-coloring-syntactic-comments))
-        (setq font-lock-syntactic-face-function
-              'context-coloring-font-lock-syntactic-string-function)
-        (setq saved-function-p t)))
+    (let ((min (or min (point-min)))
+          (max (or max (point-max)))
+          (font-lock-syntactic-face-function
+           (cond
+            ((and context-coloring-syntactic-comments
+                  (not context-coloring-syntactic-strings))
+             'context-coloring-font-lock-syntactic-comment-function)
+            ((and context-coloring-syntactic-strings
+                  (not context-coloring-syntactic-comments))
+             'context-coloring-font-lock-syntactic-string-function)
+            (t
+             font-lock-syntactic-face-function))))
       (save-excursion
-        (font-lock-fontify-syntactically-region (point-min) (point-max)))
-      (when saved-function-p
-        (setq font-lock-syntactic-face-function old-function)))))
+        (font-lock-fontify-syntactically-region min max)
+        ;; TODO: Make configurable at the dispatch level.
+        (when (eq major-mode 'emacs-lisp-mode)
+          (font-lock-fontify-keywords-region min max))))))
 
 
 ;;; js2-mode colorization
@@ -296,25 +280,22 @@ generated by `js2-mode'."
 
 ;;; Emacs Lisp colorization
 
-(defun context-coloring-make-scope (depth level)
+(defsubst context-coloring-make-scope (depth level)
   (list
    :depth depth
    :level level
    :variables (make-hash-table)))
 
-(defun context-coloring-scope-get-depth (scope)
-  (plist-get scope :depth))
-
-(defun context-coloring-scope-get-level (scope)
+(defsubst context-coloring-scope-get-level (scope)
   (plist-get scope :level))
 
-(defun context-coloring-scope-add-variable (scope variable)
+(defsubst context-coloring-scope-add-variable (scope variable)
   (puthash variable t (plist-get scope :variables)))
 
-(defun context-coloring-scope-get-variable (scope variable)
+(defsubst context-coloring-scope-get-variable (scope variable)
   (gethash variable (plist-get scope :variables)))
 
-(defun context-coloring-get-variable-level (scope-stack variable)
+(defsubst context-coloring-get-variable-level (scope-stack variable)
   (let* (scope
          level)
     (while (and scope-stack (not level))
@@ -324,63 +305,156 @@ generated by `js2-mode'."
         (setq level (context-coloring-scope-get-level scope)))
        (t
         (setq scope-stack (cdr scope-stack)))))
-    ;; Assume global
+    ;; Assume a global variable.
     (or level 0)))
 
-(defun context-coloring-make-backtick (end enabled)
+(defsubst context-coloring-make-backtick (end enabled)
   (list
    :end end
    :enabled enabled))
 
-(defun context-coloring-backtick-get-end (backtick)
+(defsubst context-coloring-backtick-get-end (backtick)
   (plist-get backtick :end))
 
-(defun context-coloring-backtick-get-enabled (backtick)
+(defsubst context-coloring-backtick-get-enabled (backtick)
   (plist-get backtick :enabled))
 
-(defun context-coloring-backtick-enabled-p (backtick-stack)
+(defsubst context-coloring-backtick-enabled-p (backtick-stack)
   (context-coloring-backtick-get-enabled (car backtick-stack)))
 
-(defun context-coloring-make-let-value (end)
+(defsubst context-coloring-make-let-varlist (depth type)
   (list
-   :end end))
+   :depth depth
+   :type type
+   :vars '()))
 
-(defun context-coloring-let-value-get-end (let-value)
-  (plist-get let-value :end))
+(defsubst context-coloring-let-varlist-get-type (let-varlist)
+  (plist-get let-varlist :type))
 
-(defun context-coloring-emacs-lisp-identifier-syntax-p (syntax-code)
-  (or (= 2 syntax-code)
-      (= 3 syntax-code)))
+(defsubst context-coloring-let-varlist-add-var (let-varlist var)
+  (plist-put let-varlist :vars (cons var (plist-get let-varlist :vars))))
 
-(defun context-coloring-forward-sws ()
+(defsubst context-coloring-let-varlist-pop-vars (let-varlist)
+  (let ((type (context-coloring-let-varlist-get-type let-varlist))
+        (vars (plist-get let-varlist :vars)))
+    (cond
+     ;; `let' binds all at once at the end.
+     ((eq type 'let)
+      (prog1
+          vars
+        (plist-put let-varlist :vars '())))
+     ;; `let*' binds incrementally.
+     ((eq type 'let*)
+      (prog1
+          (list (car vars))
+        (plist-put let-varlist :vars (cdr vars)))))))
+
+(defsubst context-coloring-forward-sws ()
   "Move forward through whitespace and comments."
   (while (forward-comment 1)))
 
-(defun context-coloring-at-open-parenthesis ()
+(defsubst context-coloring-forward-sexp-position ()
+  "Like vanilla `forward-sexp', but just return the position."
+  (scan-sexps (point) 1))
+
+(defsubst context-coloring-emacs-lisp-identifier-syntax-p (syntax-code)
+  (or (= 2 syntax-code)
+      (= 3 syntax-code)))
+
+(defsubst context-coloring-open-parenthesis-p (syntax-code)
+  (= 4 syntax-code))
+
+(defsubst context-coloring-close-parenthesis-p (syntax-code)
+  (= 5 syntax-code))
+
+(defsubst context-coloring-expression-prefix-p (syntax-code)
+  (= 6 syntax-code))
+
+(defsubst context-coloring-at-open-parenthesis-p ()
   (= 4 (logand #xFFFF (car (syntax-after (point))))))
 
+(defsubst context-coloring-ppss-depth (ppss)
+  ;; Same as (nth 0 ppss).
+  (car ppss))
+
+(defsubst context-coloring-at-stack-depth-p (stack depth)
+  (= (plist-get (car stack) :depth) depth))
+
+(defsubst context-coloring-exact-regexp (word)
+  "Create a regexp that matches exactly WORD."
+  (concat "\\`" (regexp-quote word) "\\'"))
+
+(defsubst context-coloring-exact-or-regexp (words)
+  "Create a regexp that matches any exact word in WORDS."
+  (context-coloring-join
+   (mapcar 'context-coloring-exact-regexp words) "\\|"))
+
+(defconst context-coloring-emacs-lisp-defun-regexp
+  (context-coloring-exact-or-regexp
+   '("defun" "defun*" "defsubst" "defmacro"
+     "cl-defun" "cl-defsubst" "cl-defmacro")))
+
+(defconst context-coloring-emacs-lisp-lambda-regexp
+  (context-coloring-exact-regexp "lambda"))
+
+(defconst context-coloring-emacs-lisp-let-regexp
+  (context-coloring-exact-regexp "let"))
+
+(defconst context-coloring-emacs-lisp-let*-regexp
+  (context-coloring-exact-regexp "let*"))
+
+(defconst context-coloring-arglist-arg-regexp
+  "\\`[^&:]")
+
+(defconst context-coloring-ignored-word-regexp
+  (concat "\\`[-+]?[0-9]\\|" (context-coloring-exact-or-regexp
+                              '("t" "nil" "." "?"))))
+
+(defconst context-coloring-COMMA-CHAR 44)
+(defconst context-coloring-BACKTICK-CHAR 96)
+
+(defvar context-coloring-parse-interruptable-p t
+  "Set this to nil to force parse to continue until finished.")
+
+(defconst context-coloring-emacs-lisp-iterations-per-pause 1000
+  "Pause after this many iterations to check for user input.
+If user input is pending, stop the parse.  This makes for a
+smoother user experience for large files.
+
+As of this writing, emacs lisp colorization seems to run at about
+60,000 iterations per second.  A default value of 1000 should
+provide visually \"instant\" updates at 60 frames per second.")
+
 (defun context-coloring-emacs-lisp-colorize ()
   "Color the current buffer by parsing emacs lisp sexps."
   (with-silent-modifications
     (save-excursion
-      ;; TODO: Can probably make this lazy to the nearest defun
+      ;; TODO: Can probably make this lazy to the nearest defun.
       (goto-char (point-min))
       (let* ((inhibit-point-motion-hooks t)
              (end (point-max))
+             (iteration-count 0)
+             (last-fontified-position (point))
+             beginning-of-current-defun
+             end-of-current-defun
              (last-ppss-pos (point))
              (ppss (syntax-ppss))
-             (scope-stack `(,(context-coloring-make-scope -1 0))) ; -1 never matches a depth
-             (backtick-stack `(,(context-coloring-make-backtick -1 nil)))
-             (let-value-stack `(,(context-coloring-make-let-value -1)))
+             ppss-depth
+             ;; -1 never matches a depth.  This is a minor optimization.
+             (scope-stack `(,(context-coloring-make-scope -1 0)))
+             (backtick-stack '())
+             (let-varlist-stack '())
+             (let-var-stack '())
+             popped-vars
              one-word-found-p
              in-defun-p
              in-lambda-p
+             in-let-p
              in-let*-p
-             function-call-p
              defun-arglist
              defun-arg
              let-varlist
-             let-var
+             let-varlist-type
              variable
              variable-end
              variable-string
@@ -401,19 +475,43 @@ generated by `js2-mode'."
              child-2-end)
         (while (> end (progn (skip-syntax-forward "^()w_'" end)
                              (point)))
+          ;; Sparingly-executed tasks.
+          (setq iteration-count (1+ iteration-count))
+          (when (zerop (% iteration-count
+                          context-coloring-emacs-lisp-iterations-per-pause))
+            ;; Fontify until the end of the current defun because doing it in
+            ;; chunks based soley on point could result in partial
+            ;; re-fontifications over the contents of scopes.
+            (save-excursion
+              (end-of-defun)
+              (setq end-of-current-defun (point))
+              (beginning-of-defun)
+              (setq beginning-of-current-defun (point)))
+
+            ;; Fontify in chunks.
+            (context-coloring-maybe-colorize-comments-and-strings
+             last-fontified-position
+             (cond
+              ;; We weren't actually in a defun, so don't color the next one, as
+              ;; that could result in `font-lock' properties being added to it.
+              ((> beginning-of-current-defun (point))
+               (point))
+              (t
+               end-of-current-defun)))
+            (setq last-fontified-position (point))
+            (when (and context-coloring-parse-interruptable-p
+                       (input-pending-p))
+              (throw 'interrupted t)))
+
           (setq token-pos (point))
           (setq token-syntax (syntax-after token-pos))
+          (setq token-syntax-code (logand #xFFFF (car token-syntax)))
+          (setq token-char (char-after))
           (setq ppss (parse-partial-sexp last-ppss-pos token-pos nil nil ppss))
           (setq last-ppss-pos token-pos)
-          ;; `skip-syntax-forward' leaves the point at the delimiter, move past
-          ;; it.
-          (setq token-syntax-code (logand #xFFFF (car token-syntax)))
-          (setq token-char (string-to-char (buffer-substring-no-properties
-                                            token-pos
-                                            (1+ token-pos))))
           (cond
 
-           ;; Resolve invalid state
+           ;; Resolve an invalid state.
            ((cond
              ;; Inside string?
              ((nth 3 ppss)
@@ -422,141 +520,142 @@ generated by `js2-mode'."
               t)
              ;; Inside comment?
              ((nth 4 ppss)
-              (skip-syntax-forward "^>" end) ; comment ender
+              (skip-syntax-forward "^>" end)
               t)))
 
-           ;; Expression prefix
-           ;; Has to come first in case of commas
-           ((= 6 token-syntax-code)
+           ;; Need to check early in case there's a comma.
+           ((context-coloring-expression-prefix-p token-syntax-code)
             (forward-char)
             (cond
-             ;; Just outright skip top-level symbols
-             ((not (or (cadr backtick-stack)
-                       (= token-char 96))) ; 96 = '`'
-              (goto-char (scan-sexps (point) 1)))
-             ((or (= token-char 96)  ; 96 = '`'
-                  (= token-char 44)) ; 44 = ','
-              ;; Have to manage backticks
+             ;; Skip top-level symbols.
+             ((not (or backtick-stack
+                       (= token-char context-coloring-BACKTICK-CHAR)))
+              (goto-char (context-coloring-forward-sexp-position)))
+             ;; Push a backtick state.
+             ((or (= token-char context-coloring-BACKTICK-CHAR)
+                  (= token-char context-coloring-COMMA-CHAR))
               (setq backtick-stack (cons (context-coloring-make-backtick
-                                          (scan-sexps (point) 1) ; End of the backtick
-                                          (= token-char 96)) ; 96 = '`'
+                                          (context-coloring-forward-sexp-position)
+                                          (= token-char context-coloring-BACKTICK-CHAR))
                                          backtick-stack)))))
 
-           ;; End backtick
-           ((and (cadr backtick-stack)
+           ;; Pop a backtick state.
+           ((and backtick-stack
                  (>= (point) (context-coloring-backtick-get-end (car backtick-stack))))
             (setq backtick-stack (cdr backtick-stack)))
 
-           ;; Restricted by backtick
-           ((and (cadr backtick-stack)
+           ;; Restricted by an enabled backtick.
+           ((and backtick-stack
                  (context-coloring-backtick-enabled-p backtick-stack))
             (forward-char))
 
-           ;; Opening delimiter
-           ((= 4 token-syntax-code)
+           ((context-coloring-open-parenthesis-p token-syntax-code)
             (forward-char)
-            ;; Lookahead for scopes / function calls
+            ;; Look for function calls.
             (context-coloring-forward-sws)
             (setq child-0-pos (point))
             (setq child-0-syntax (syntax-after child-0-pos))
             (setq child-0-syntax-code (logand #xFFFF (car child-0-syntax)))
             (cond
-             ;; Word
              ((context-coloring-emacs-lisp-identifier-syntax-p child-0-syntax-code)
               (setq one-word-found-p t)
               (setq child-0-end (scan-sexps child-0-pos 1))
               (setq child-0-string (buffer-substring-no-properties child-0-pos child-0-end))
               (cond
-               ((string-match-p "\\`defun\\'\\|\\`defmacro\\'" child-0-string)
+               ;; Parse a var in a `let' varlist.
+               ((and
+                 let-varlist-stack
+                 (context-coloring-at-stack-depth-p
+                  let-varlist-stack
+                  ;; 1- because we're inside the varlist.
+                  (1- (context-coloring-ppss-depth ppss))))
+                (context-coloring-let-varlist-add-var
+                 (car let-varlist-stack)
+                 (intern child-0-string))
+                (setq let-var-stack (cons (context-coloring-ppss-depth ppss)
+                                          let-var-stack)))
+               ((string-match-p context-coloring-emacs-lisp-defun-regexp child-0-string)
                 (setq in-defun-p t))
-               ((string-match-p "\\`lambda\\'" child-0-string)
+               ((string-match-p context-coloring-emacs-lisp-lambda-regexp child-0-string)
                 (setq in-lambda-p t))
-               ((string-match-p "\\`let\\*\\'" child-0-string)
-                (setq in-let*-p t))
-               ;; Assume a global function call
-               (t
-                (setq function-call-p t)))))
+               ((string-match-p context-coloring-emacs-lisp-let-regexp child-0-string)
+                (setq in-let-p t)
+                (setq let-varlist-type 'let))
+               ((string-match-p context-coloring-emacs-lisp-let*-regexp child-0-string)
+                (setq in-let*-p t)
+                (setq let-varlist-type 'let*)))))
             (when (or in-defun-p
                       in-lambda-p
+                      in-let-p
                       in-let*-p)
               (setq scope-stack (cons (context-coloring-make-scope
-                                       (nth 0 ppss)
+                                       (context-coloring-ppss-depth ppss)
                                        (1+ (context-coloring-scope-get-level
                                             (car scope-stack))))
                                       scope-stack)))
-            ;; TODO: Probably redundant and wasteful
+            ;; TODO: Maybe wasteful but doing this conditionally doesn't make
+            ;; much of a difference.
             (context-coloring-colorize-region token-pos
                                               (scan-sexps token-pos 1)
                                               (context-coloring-scope-get-level
                                                (car scope-stack)))
-            (when function-call-p
-              (context-coloring-colorize-region child-0-pos child-0-end 0)
-              (setq function-call-p nil))
             (cond
              ((or in-defun-p
                   in-lambda-p)
               (goto-char child-0-end)
               (when in-defun-p
-                ;; Lookahead for defun name
+                ;; Look for a function name.
                 (context-coloring-forward-sws)
                 (setq child-1-pos (point))
                 (setq child-1-syntax (syntax-after child-1-pos))
                 (setq child-1-syntax-code (logand #xFFFF (car child-1-syntax)))
                 (cond
-                 ;; Word
                  ((context-coloring-emacs-lisp-identifier-syntax-p child-1-syntax-code)
                   (setq child-1-end (scan-sexps child-1-pos 1))
-                  ;; defuns are global so use level 0
+                  ;; Defuns are global, so use level 0.
                   (context-coloring-colorize-region child-1-pos child-1-end 0)
                   (goto-char child-1-end))))
-              ;; Lookahead for parameters
+              ;; Look for an arglist.
               (context-coloring-forward-sws)
-              (when (context-coloring-at-open-parenthesis)
-                ;; Actually it should be `child-1-end' for `lambda'.
-                (setq child-2-end (scan-sexps (point) 1))
+              (when (context-coloring-at-open-parenthesis-p)
+                ;; (Actually it should be `child-1-end' for `lambda'.)
+                (setq child-2-end (context-coloring-forward-sexp-position))
                 (setq defun-arglist (read (buffer-substring-no-properties
                                            (point)
                                            child-2-end)))
                 (while defun-arglist
                   (setq defun-arg (car defun-arglist))
                   (when (and (symbolp defun-arg)
-                             (string-match-p "\\`[^&:]" (symbol-name defun-arg)))
+                             (string-match-p
+                              context-coloring-arglist-arg-regexp
+                              (symbol-name defun-arg)))
                     (context-coloring-scope-add-variable
                      (car scope-stack)
                      defun-arg))
                   (setq defun-arglist (cdr defun-arglist)))
                 (goto-char child-2-end))
-              ;; Cleanup
+              ;; Cleanup.
               (setq in-defun-p nil)
               (setq in-lambda-p nil))
-             (in-let*-p
+             ((or in-let-p
+                  in-let*-p)
               (goto-char child-0-end)
-              ;; Lookahead for bindings
+              ;; Look for a varlist.
               (context-coloring-forward-sws)
               (setq child-1-pos (point))
               (setq child-1-syntax (syntax-after child-1-pos))
               (setq child-1-syntax-code (logand #xFFFF (car child-1-syntax)))
-              (when (= 4 child-1-syntax-code)
-                (setq child-1-end (scan-sexps (point) 1))
-                (setq let-varlist (read (buffer-substring-no-properties
-                                         (point)
-                                         child-1-end)))
-                (while let-varlist
-                  (setq let-var (car let-varlist))
-                  (cond
-                   ((symbolp let-var)
-                    (context-coloring-scope-add-variable
-                     (car scope-stack)
-                     let-var))
-                   ((listp let-var)
-                    (context-coloring-scope-add-variable
-                     (car scope-stack)
-                     (car let-var))
-                    ;; TODO: Recurse or use stack to eval var value
-                    ))
-                  (setq let-varlist (cdr let-varlist)))
-                (goto-char child-1-end))
-              ;; Cleanup
+              (when (context-coloring-open-parenthesis-p child-1-syntax-code)
+                ;; Begin parsing the varlist.
+                (forward-char)
+                (setq let-varlist-stack (cons (context-coloring-make-let-varlist
+                                               ;; 1+ because we parsed it at a
+                                               ;; higher depth.
+                                               (1+ (context-coloring-ppss-depth ppss))
+                                               let-varlist-type)
+                                              let-varlist-stack)))
+              ;; Cleanup.
+              (setq in-let-p nil)
               (setq in-let*-p nil))
              (t
               (goto-char (cond
@@ -565,43 +664,80 @@ generated by `js2-mode'."
                            (1+ child-0-end))
                           (t
                            (1+ token-pos))))))
-            ;; Cleanup
+            ;; Cleanup.
             (setq one-word-found-p nil))
 
-           ;; Word (variable)
            ((context-coloring-emacs-lisp-identifier-syntax-p token-syntax-code)
-            (setq variable-end (scan-sexps (point) 1))
+            (setq variable-end (context-coloring-forward-sexp-position))
             (setq variable-string (buffer-substring-no-properties
                                    token-pos
                                    variable-end))
             (cond
-             ;; Ignore constants such as numbers, keywords, t, nil. These can't
+             ;; Ignore constants such as numbers, keywords, t, nil.  These can't
              ;; be rebound, so they should be treated like syntax.
-             ((string-match-p "\\`[-+]?[0-9]\\|\\`t\\'\\|\\`nil\\'" variable-string))
+             ((string-match-p context-coloring-ignored-word-regexp variable-string))
              ((keywordp (read variable-string)))
              (t
               (setq variable (intern variable-string))
-              (setq variable-scope-level
-                    (context-coloring-get-variable-level scope-stack variable))
-              (when (/= variable-scope-level (context-coloring-scope-get-level
-                                              (car scope-stack)))
-                (context-coloring-colorize-region
-                 token-pos
-                 variable-end
-                 variable-scope-level))))
+              (cond
+               ;; Parse a `let' varlist's uninitialized var.
+               ((and
+                 let-varlist-stack
+                 (context-coloring-at-stack-depth-p
+                  let-varlist-stack
+                  ;; 1- because we're inside the varlist.
+                  (1- (context-coloring-ppss-depth ppss))))
+                (setq let-varlist (car let-varlist-stack))
+                (setq let-varlist-type (context-coloring-let-varlist-get-type let-varlist))
+                (cond
+                 ;; Defer `let' binding until the end of the varlist.
+                 ((eq let-varlist-type 'let)
+                  (context-coloring-let-varlist-add-var let-varlist variable))
+                 ;; Bind a `let*' right away.
+                 ((eq let-varlist-type 'let*)
+                  (context-coloring-scope-add-variable (car scope-stack) variable))))
+               (t
+                (setq variable-scope-level
+                      (context-coloring-get-variable-level scope-stack variable))
+                (when (/= variable-scope-level (context-coloring-scope-get-level
+                                                (car scope-stack)))
+                  (context-coloring-colorize-region
+                   token-pos
+                   variable-end
+                   variable-scope-level))))))
             (goto-char variable-end))
 
-           ;; Closing delimiter
-           ((= 5 token-syntax-code)
+           ((context-coloring-close-parenthesis-p token-syntax-code)
             (forward-char)
-            ;; End scope
             (setq ppss (parse-partial-sexp last-ppss-pos (point) nil nil ppss))
             (setq last-ppss-pos (point))
-            (when (= (nth 0 ppss) (context-coloring-scope-get-depth (car scope-stack)))
-              (setq scope-stack (cdr scope-stack))))
-
-           ))))
-    (context-coloring-maybe-colorize-comments-and-strings)))
+            (setq ppss-depth (context-coloring-ppss-depth ppss))
+            ;; TODO: Order might matter here but I'm not certain.
+            (when (context-coloring-at-stack-depth-p scope-stack ppss-depth)
+              (setq scope-stack (cdr scope-stack)))
+            (when (and
+                   let-var-stack
+                   (= (car let-var-stack) ppss-depth))
+              (setq let-var-stack (cdr let-var-stack))
+              (when (eq (context-coloring-let-varlist-get-type (car let-varlist-stack))
+                        'let*)
+                (setq popped-vars (context-coloring-let-varlist-pop-vars
+                                   (car let-varlist-stack)))))
+            (when (and
+                   let-varlist-stack
+                   (context-coloring-at-stack-depth-p let-varlist-stack ppss-depth))
+              (setq popped-vars (context-coloring-let-varlist-pop-vars
+                                 (car let-varlist-stack)))
+              (setq let-varlist-stack (cdr let-varlist-stack)))
+            (while popped-vars
+              (context-coloring-scope-add-variable (car scope-stack) (car popped-vars))
+              (setq popped-vars (cdr popped-vars))))
+
+           ))
+        ;; Fontify the last stretch.
+        (context-coloring-maybe-colorize-comments-and-strings
+         last-fontified-position
+         (point))))))
 
 
 ;;; Shell command scopification / colorization
@@ -685,7 +821,7 @@ read the scopifier's response asynchronously and apply a parsed
 list of tokens to `context-coloring-apply-tokens'.
 
 Invoke CALLBACK when complete."
-  (let ((buffer context-coloring-buffer))
+  (let ((buffer (current-buffer)))
     (context-coloring-scopify-shell-command
      command
      (lambda (output)
@@ -706,6 +842,15 @@ Invoke CALLBACK when complete."
 (defvar context-coloring-mode-hash-table (make-hash-table :test 'eq)
   "Map major mode names to dispatch property lists.")
 
+(defun context-coloring-get-dispatch-for-mode (mode)
+  "Return the dispatch for MODE (or a derivative mode)."
+  (let ((parent mode)
+        dispatch)
+    (while (and parent
+                (not (setq dispatch (gethash parent context-coloring-mode-hash-table)))
+                (setq parent (get parent 'derived-mode-parent))))
+    dispatch))
+
 (defun context-coloring-define-dispatch (symbol &rest properties)
   "Define a new dispatch named SYMBOL with PROPERTIES.
 
@@ -757,51 +902,7 @@ should be numeric, e.g. \"2\", \"19700101\", \"1.2.3\",
       (error "No colorizer, scopifier or command defined for dispatch"))
     (puthash symbol properties context-coloring-dispatch-hash-table)
     (dolist (mode modes)
-      (when (null (gethash mode context-coloring-mode-hash-table))
-        (puthash mode properties context-coloring-mode-hash-table)))))
-
-(context-coloring-define-dispatch
- 'javascript-node
- :modes '(js-mode js3-mode)
- :executable "scopifier"
- :command "scopifier"
- :version "v1.1.1")
-
-(context-coloring-define-dispatch
- 'javascript-js2
- :modes '(js2-mode)
- :colorizer 'context-coloring-js2-colorize
- :setup
- (lambda ()
-   (add-hook 'js2-post-parse-callbacks 'context-coloring-colorize nil t))
- :teardown
- (lambda ()
-   (remove-hook 'js2-post-parse-callbacks 'context-coloring-colorize t)))
-
-(context-coloring-define-dispatch
- 'emacs-lisp
- :modes '(emacs-lisp-mode)
- :colorizer 'context-coloring-emacs-lisp-colorize)
-
-(defun context-coloring-dispatch (&optional callback)
-  "Determine the optimal track for scopification / coloring of
-the current buffer, then execute it.
-
-Invoke CALLBACK when complete.  It is invoked synchronously for
-elisp tracks, and asynchronously for shell command tracks."
-  (let ((dispatch (gethash major-mode context-coloring-mode-hash-table))
-        colorizer
-        scopifier
-        command)
-    (cond
-     ((setq colorizer (plist-get dispatch :colorizer))
-      (funcall colorizer)
-      (when callback (funcall callback)))
-     ((setq scopifier (plist-get dispatch :scopifier))
-      (context-coloring-apply-tokens (funcall scopifier))
-      (when callback (funcall callback)))
-     ((setq command (plist-get dispatch :command))
-      (context-coloring-scopify-and-colorize command callback)))))
+      (puthash mode properties context-coloring-mode-hash-table))))
 
 
 ;;; Colorization
@@ -831,9 +932,9 @@ used.")
   (context-coloring-kill-scopifier)
   (setq context-coloring-changed t))
 
-(defun context-coloring-maybe-colorize ()
+(defun context-coloring-maybe-colorize (buffer)
   "Colorize the current buffer if it has changed."
-  (when (and (eq context-coloring-buffer (window-buffer (selected-window)))
+  (when (and (eq buffer (current-buffer))
              context-coloring-changed)
     (setq context-coloring-changed nil)
     (context-coloring-colorize)))
@@ -878,7 +979,7 @@ produces (1 0 0), \"19700101\" produces (19700101), etc."
   "Asynchronously invoke CALLBACK with a predicate indicating
 whether the current scopifier version satisfies the minimum
 version number required for the current major mode."
-  (let ((dispatch (gethash major-mode context-coloring-mode-hash-table)))
+  (let ((dispatch (context-coloring-get-dispatch-for-mode major-mode)))
     (when dispatch
       (let ((version (plist-get dispatch :version))
             (command (plist-get dispatch :command)))
@@ -1234,7 +1335,7 @@ precedence, i.e. the car of `custom-enabled-themes'."
            "#dca3a3"))
 
 
-;;; Minor mode
+;;; Change detection
 
 (defvar-local context-coloring-colorize-idle-timer nil
   "The currently-running idle timer.")
@@ -1245,18 +1346,90 @@ precedence, i.e. the car of `custom-enabled-themes'."
 Increase this if your machine is high-performing.  Decrease it if
 it ain't.
 
-Supported modes: `js-mode', `js3-mode'"
+Supported modes: `js-mode', `js3-mode', `emacs-lisp-mode'"
   :group 'context-coloring)
 
 (defun context-coloring-setup-idle-change-detection ()
   "Setup idle change detection."
   (add-hook
    'after-change-functions 'context-coloring-change-function nil t)
+  (add-hook
+   'kill-buffer-hook 'context-coloring-teardown-idle-change-detection nil t)
   (setq context-coloring-colorize-idle-timer
         (run-with-idle-timer
          context-coloring-delay
          t
-         'context-coloring-maybe-colorize)))
+         'context-coloring-maybe-colorize
+         (current-buffer))))
+
+(defun context-coloring-teardown-idle-change-detection ()
+  "Teardown idle change detection."
+  (context-coloring-kill-scopifier)
+  (when context-coloring-colorize-idle-timer
+    (cancel-timer context-coloring-colorize-idle-timer))
+  (remove-hook
+   'kill-buffer-hook 'context-coloring-teardown-idle-change-detection t)
+  (remove-hook
+   'after-change-functions 'context-coloring-change-function t))
+
+
+;;; Built-in dispatches
+
+(context-coloring-define-dispatch
+ 'javascript-node
+ :modes '(js-mode js3-mode)
+ :executable "scopifier"
+ :command "scopifier"
+ :version "v1.1.1")
+
+(context-coloring-define-dispatch
+ 'javascript-js2
+ :modes '(js2-mode)
+ :colorizer 'context-coloring-js2-colorize
+ :setup
+ (lambda ()
+   (add-hook 'js2-post-parse-callbacks 'context-coloring-colorize nil t))
+ :teardown
+ (lambda ()
+   (remove-hook 'js2-post-parse-callbacks 'context-coloring-colorize t)))
+
+(context-coloring-define-dispatch
+ 'emacs-lisp
+ :modes '(emacs-lisp-mode)
+ :colorizer 'context-coloring-emacs-lisp-colorize
+ :setup 'context-coloring-setup-idle-change-detection
+ :teardown 'context-coloring-teardown-idle-change-detection)
+
+(defun context-coloring-dispatch (&optional callback)
+  "Determine the optimal track for scopification / coloring of
+the current buffer, then execute it.
+
+Invoke CALLBACK when complete.  It is invoked synchronously for
+elisp tracks, and asynchronously for shell command tracks."
+  (let* ((dispatch (context-coloring-get-dispatch-for-mode major-mode))
+         (colorizer (plist-get dispatch :colorizer))
+         (scopifier (plist-get dispatch :scopifier))
+         (command (plist-get dispatch :command))
+         interrupted-p)
+    (cond
+     ((or colorizer scopifier)
+      (setq interrupted-p
+            (catch 'interrupted
+              (cond
+               (colorizer
+                (funcall colorizer))
+               (scopifier
+                (context-coloring-apply-tokens (funcall scopifier))))))
+      (cond
+       (interrupted-p
+        (setq context-coloring-changed t))
+       (t
+        (when callback (funcall callback)))))
+     (command
+      (context-coloring-scopify-and-colorize command callback)))))
+
+
+;;; Minor mode
 
 ;;;###autoload
 (define-minor-mode context-coloring-mode
@@ -1264,32 +1437,28 @@ Supported modes: `js-mode', `js3-mode'"
   nil " Context" nil
   (if (not context-coloring-mode)
       (progn
-        (context-coloring-kill-scopifier)
-        (when context-coloring-colorize-idle-timer
-          (cancel-timer context-coloring-colorize-idle-timer))
-        (let ((dispatch (gethash major-mode context-coloring-mode-hash-table)))
+        (let ((dispatch (context-coloring-get-dispatch-for-mode major-mode)))
           (when dispatch
             (let ((command (plist-get dispatch :command))
                   (teardown (plist-get dispatch :teardown)))
               (when command
-                (remove-hook
-                 'after-change-functions 'context-coloring-change-function t))
+                (context-coloring-teardown-idle-change-detection))
               (when teardown
                 (funcall teardown)))))
         (font-lock-mode)
         (jit-lock-mode t))
 
-    ;; Remember this buffer.  This value should not be dynamically-bound.
-    (setq context-coloring-buffer (current-buffer))
-
     ;; Font lock is incompatible with this mode; the converse is also true.
     (font-lock-mode 0)
     (jit-lock-mode nil)
 
+    ;; ...but we do use font-lock functions here.
+    (font-lock-set-defaults)
+
     ;; Safely change the valye of this function as necessary.
     (make-local-variable 'font-lock-syntactic-face-function)
 
-    (let ((dispatch (gethash major-mode context-coloring-mode-hash-table)))
+    (let ((dispatch (context-coloring-get-dispatch-for-mode major-mode)))
       (if dispatch
           (progn
             (let ((command (plist-get dispatch :command))
@@ -1320,7 +1489,8 @@ Supported modes: `js-mode', `js3-mode'"
                 (funcall setup))
               ;; Colorize once initially.
               (when colorize-initially-p
-                (context-coloring-colorize))))
+                (let ((context-coloring-parse-interruptable-p nil))
+                  (context-coloring-colorize)))))
         (when (null dispatch)
           (message "Context coloring is not available for this major mode"))))))