[MLton] emacs def-use mode

[Jake Donham]

Hi,

The emacs def-use mode is nice! Appended is a little patch to give it a
stack of where you've been, like you get with tags mode. It is based on
etags.el.

Jake

--- def-use-mode.el     (revision 5255)
+++ def-use-mode.el     (working copy)
@@ -67,10 +67,19 @@
   :type 'integer
   :group 'def-use)

+(defcustom def-use-marker-ring-length 16
+  "*Length of marker ring `def-use-marker-ring'."
+  :group 'def-use
+  :type 'integer)
+
+(defvar def-use-marker-ring (make-ring def-use-marker-ring-length)
+  "Ring of markers which are locations from which \\[def-use-goto-ref] was invoked.")
+
 (defcustom def-use-key-bindings
   '(("[(control c) (control d)]" . def-use-jump-to-def)
     ("[(control c) (control n)]" . def-use-jump-to-next)
     ("[(control c) (control p)]" . def-use-jump-to-prev)
+    ("[(control c) (control m)]" . def-use-pop-ref-mark)
     ("[(control c) (control s)]" . def-use-show-dus)
     ("[(control c) (control l)]" . def-use-list-all-refs)
     ("[(control c) (control v)]" . def-use-show-info))
@@ -202,6 +211,7 @@
 (defun def-use-goto-ref (ref &optional other-window)
   "Finds the referenced source and moves point to the referenced
 position."
+  (ring-insert def-use-marker-ring (point-marker))
   (cond
    ((not (file-readable-p (def-use-ref-src ref)))
     (compat-error "Referenced file %s can not be read" (def-use-ref-src ref)))
@@ -222,6 +232,17 @@
               (copy-list (def-use-sym-to-uses sym)))
         (function def-use-ref<)))

+(defun def-use-pop-ref-mark ()
+  "Pop back to where \\[def-use-goto-ref] was last invoked."
+  (interactive)
+  (if (ring-empty-p def-use-marker-ring)
+      (error "No previous locations for def-use-goto-ref invocation"))
+  (let ((marker (ring-remove def-use-marker-ring 0)))
+    (switch-to-buffer (or (marker-buffer marker)
+                          (error "The marked buffer has been deleted")))
+    (goto-char (marker-position marker))
+    (set-marker marker nil nil)))
+
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