Closes #351: sort mirrors by nesting depth when updating

yasnippet-tests.el

@@ -105,6 +105,13 @@
   (should (string= (yas--buffer-contents)
                    "<%= f.submit \"Send\", :disable_with => 'Sending...' %>")))
 
+(ert-deftest deep-nested-mirroring-issue-351 ()
+  (with-temp-buffer
+    (yas-minor-mode 1)
+    (yas-expand-snippet "${1:FOOOOOOO}${2:$1}${3:$2}${4:$3}")
+    (ert-simulate-command `(yas-mock-insert "abc"))
+    (should (string= (yas--buffer-contents) "abcabcabcabc"))))
+
 ;; (ert-deftest in-snippet-undo ()
 ;;   (with-temp-buffer
 ;;     (yas-minor-mode 1)

yasnippet.el

@@ -2923,7 +2923,8 @@ Use this in primary and mirror transformations to tget."
   start end
   (transform nil)
   parent-field
-  next)
+  next
+  depth)
 
 (defstruct (yas--exit (:constructor yas--make-exit (marker)))
   marker
@@ -4155,6 +4156,26 @@ When multiple expressions are found, only the last one counts."
               #'(lambda (r1 r2)
                   (>= (car r1) (car r2))))))
 
+(defun yas--calculate-mirror-depth (mirror &optional traversed)
+  (let* ((parent (yas--mirror-parent-field mirror))
+         (parents-mirrors (and parent
+                               (yas--field-mirrors parent))))
+    (or (yas--mirror-depth mirror)
+        (setf (yas--mirror-depth mirror)
+              (cond ((memq mirror traversed)
+                     0)
+                    ((and parent parents-mirrors)
+                     (1+ (reduce #'max
+                                 (mapcar #'(lambda (m)
+                                             (yas--calculate-mirror-depth m
+                                                                          (cons mirror
+                                                                                traversed)))
+                                         parents-mirrors))))
+                    (parent
+                     1)
+                    (t
+                     0))))))
+
 (defun yas--update-mirrors (snippet)
   "Updates all the mirrors of SNIPPET."
   (save-excursion
@@ -4173,7 +4194,8 @@ When multiple expressions are found, only the last one counts."
                                ;; another mirror to need reupdating
                                ;;
                                #'(lambda (field-and-mirror1 field-and-mirror2)
-                                   (yas--mirror-parent-field (cdr field-and-mirror1)))))
+                                   (> (yas--calculate-mirror-depth (cdr field-and-mirror1))
+                                      (yas--calculate-mirror-depth (cdr field-and-mirror2))))))
       (let* ((field (car field-and-mirror))
              (mirror (cdr field-and-mirror))
              (parent-field (yas--mirror-parent-field mirror)))