Emacs repo comment about org-element's use of avl-tree--*

Emacs repo comment about org-element's use of avl-tree--*

[Kyle Meyer]

Hello,

The commit below was made in Emacs's master branch (fe15532eef).  I'm
posting it here for review/discussion rather than backporting it.

-- >8 --
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Thu, 11 Jan 2018 11:33:03 -0500
Subject: [PATCH] * lisp/org/org-element.el: Add comment about use of internal
 functions

---
 lisp/org/org-element.el | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lisp/org/org-element.el b/lisp/org/org-element.el
index 7a40d6933c..844349c2fc 100644
--- a/lisp/org/org-element.el
+++ b/lisp/org/org-element.el
@@ -4950,6 +4950,7 @@ org-element--cache-compare
 (defsubst org-element--cache-root ()
   "Return root value in cache.
 This function assumes `org-element--cache' is a valid AVL tree."
+  ;; FIXME: Why use internal functions of avl-tree?
   (avl-tree--node-left (avl-tree--dummyroot org-element--cache)))
 
 
@@ -4978,6 +4979,7 @@ org-element--cache-find
 		    (aref (car org-element--cache-sync-requests) 0)))
 	(node (org-element--cache-root))
 	lower upper)
+    ;; FIXME: Why use internal functions of avl-tree?
     (while node
       (let* ((element (avl-tree--node-data node))
 	     (begin (org-element-property :begin element)))
-- 
2.11.0

Re: Emacs repo comment about org-element's use of avl-tree--*

[Nicolas Goaziou]

Hello,

Kyle Meyer <kyle@kyleam.com> writes:

> The commit below was made in Emacs's master branch (fe15532eef).  I'm
> posting it here for review/discussion rather than backporting it.

[...]

> +  ;; FIXME: Why use internal functions of avl-tree?
>    (avl-tree--node-left (avl-tree--dummyroot org-element--cache)))

[...]

> +    ;; FIXME: Why use internal functions of avl-tree?
>      (while node
>        (let* ((element (avl-tree--node-data node))
>  	     (begin (org-element-property :begin element)))

IIRC, this is because external functions do not give enough control over
the tree. For example, the code needs to be able to find a node whose
key matches a given predicate, efficiently.

This is not much of an issue, however. This implementation detail may
change at some point.

Regards,

-- 
Nicolas Goaziou

Re: Emacs repo comment about org-element's use of avl-tree--*

[Kyle Meyer]

Nicolas Goaziou <mail@nicolasgoaziou.fr> writes:

> IIRC, this is because external functions do not give enough control over
> the tree. For example, the code needs to be able to find a node whose
> key matches a given predicate, efficiently.
>
> This is not much of an issue, however. This implementation detail may
> change at some point.

OK, thanks for your response.

-- 
Kyle