master f94e93a6ee 7/9: org-cite-list-citations: Cache footnote-definition searches

[Eli Zaretskii]

branch: master
commit f94e93a6eec92d834a6b545d8d4b68280b0993b0
Author: Ihor Radchenko <yantar92@gmail.com>
Commit: Eli Zaretskii <eliz@gnu.org>

    org-cite-list-citations: Cache footnote-definition searches
    
    * lisp/org/oc.el (org-cite-list-citations): Avoid quadratic complexity.
    Pre-calculate list of all footnote definitions and cache the footnote
    label search hits.  Do not make `org-element-map' accumulate unused
    result.
---
 lisp/org/oc.el | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/lisp/org/oc.el b/lisp/org/oc.el
index eb5f519cb6..c4cd0268c7 100644
--- a/lisp/org/oc.el
+++ b/lisp/org/oc.el
@@ -808,6 +808,8 @@ INFO is the export communication channel, as a property 
list."
   (or (plist-get info :citations)
       (letrec ((cites nil)
                (tree (plist-get info :parse-tree))
+               (definition-cache (make-hash-table :test #'equal))
+               (definition-list nil)
                (find-definition
                 ;; Find definition for standard reference LABEL.  At
                 ;; this point, it is impossible to rely on
@@ -816,11 +818,21 @@ INFO is the export communication channel, as a property 
list."
                 ;; un-processed citation objects.  So we use
                 ;; a simplified version of the function above.
                 (lambda (label)
-                  (org-element-map tree 'footnote-definition
-                    (lambda (d)
-                      (and (equal label (org-element-property :label d))
-                           (or (org-element-contents d) "")))
-                    info t)))
+                  (or (gethash label definition-cache)
+                      (org-element-map
+                          (or definition-list
+                              (setq definition-list
+                                    (org-element-map
+                                        tree
+                                        'footnote-definition
+                                      #'identity info)))
+                          'footnote-definition
+                        (lambda (d)
+                          (and (equal label (org-element-property :label d))
+                               (puthash label
+                                        (or (org-element-contents d) "")
+                                        definition-cache)))
+                        info t))))
                (search-cites
                 (lambda (data)
                   (org-element-map data '(citation footnote-reference)
@@ -834,7 +846,8 @@ INFO is the export communication channel, as a property 
list."
                         (_
                          (let ((label (org-element-property :label datum)))
                            (funcall search-cites
-                                    (funcall find-definition label))))))
+                                    (funcall find-definition label)))))
+                      nil)
                     info nil 'footnote-definition t))))
         (funcall search-cites tree)
         (let ((result (nreverse cites)))