+(defvar custom--sort-vars-table)
+(defvar custom--sort-vars-result)
+
+(defun custom--sort-vars (vars)
+ "Sort VARS based on custom dependencies.
+VARS is a list whose elements have the same form as the ARGS
+arguments to `custom-theme-set-variables'. Return the sorted
+list, in which A occurs before B if B was defined with a
+`:set-after' keyword specifying A (see `defcustom')."
+ (let ((custom--sort-vars-table (make-hash-table))
+ (dependants (make-hash-table))
+ (custom--sort-vars-result nil)
+ last)
+ ;; Construct a pair of tables keyed with the symbols of VARS.
+ (dolist (var vars)
+ (puthash (car var) (cons t var) custom--sort-vars-table)
+ (puthash (car var) var dependants))
+ ;; From the second table, remove symbols that are depended-on.
+ (dolist (var vars)
+ (dolist (dep (get (car var) 'custom-dependencies))
+ (remhash dep dependants)))
+ ;; If a variable is "stand-alone", put it last if it's a minor
+ ;; mode or has a :require flag. This is not really necessary, but
+ ;; putting minor modes last helps ensure that the mode function
+ ;; sees other customized values rather than default values.
+ (maphash (lambda (sym var)
+ (when (and (null (get sym 'custom-dependencies))
+ (or (nth 3 var)
+ (eq (get sym 'custom-set)
+ 'custom-set-minor-mode)))
+ (remhash sym dependants)
+ (push var last)))
+ dependants)
+ ;; The remaining symbols depend on others but are not
+ ;; depended-upon. Do a depth-first topological sort.
+ (maphash #'custom--sort-vars-1 dependants)
+ (nreverse (append last custom--sort-vars-result))))
+
+(defun custom--sort-vars-1 (sym &optional _ignored)
+ (let ((elt (gethash sym custom--sort-vars-table)))
+ ;; The car of the hash table value is nil if the variable has
+ ;; already been processed, `dependant' if it is a dependant in the
+ ;; current graph descent, and t otherwise.
+ (when elt
+ (cond
+ ((eq (car elt) 'dependant)
+ (error "Circular custom dependency on `%s'" sym))
+ ((car elt)
+ (setcar elt 'dependant)
+ (dolist (dep (get sym 'custom-dependencies))
+ (custom--sort-vars-1 dep))
+ (setcar elt nil)
+ (push (cdr elt) custom--sort-vars-result))))))
+