master 5b3d4e7bf0 1/9: org-export-get-footnote-definition: Pre-cache references in parse tree

[Eli Zaretskii]

branch: master
commit 5b3d4e7bf0b6a1eb576e1c6e6592028e3589f792
Author: Ihor Radchenko <yantar92@gmail.com>
Commit: Eli Zaretskii <eliz@gnu.org>

    org-export-get-footnote-definition: Pre-cache references in parse tree
    
    * lisp/org/ox.el (org-export-get-footnote-definition): Pre-process parse
    tree once to filter out all non-footnote elements.  This speeds up
    subsequent footnote definition searches.
---
 lisp/org/ox.el | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/lisp/org/ox.el b/lisp/org/ox.el
index 2a3edaa500..7f90dc36f7 100644
--- a/lisp/org/ox.el
+++ b/lisp/org/ox.el
@@ -3748,28 +3748,33 @@ definition can be found, raise an error."
     (if (not label) (org-element-contents footnote-reference)
       (let ((cache (or (plist-get info :footnote-definition-cache)
                       (let ((hash (make-hash-table :test #'equal)))
+                         ;; Cache all the footnotes in document for
+                         ;; later search.
+                         (org-element-map (plist-get info :parse-tree)
+                             '(footnote-definition footnote-reference)
+                           (lambda (f)
+                            ;; Skip any standard footnote reference
+                            ;; since those cannot contain a
+                            ;; definition.
+                             (unless (eq (org-element-property :type f) 
'standard)
+                               (puthash
+                                (cons :element (org-element-property :label f))
+                                f
+                                hash)))
+                           info)
                         (plist-put info :footnote-definition-cache hash)
                         hash))))
        (or
         (gethash label cache)
         (puthash label
-                 (org-element-map (plist-get info :parse-tree)
-                     '(footnote-definition footnote-reference)
-                   (lambda (f)
-                     (cond
-                      ;; Skip any footnote with a different label.
-                      ;; Also skip any standard footnote reference
-                      ;; with the same label since those cannot
-                      ;; contain a definition.
-                      ((not (equal (org-element-property :label f) label)) nil)
-                      ((eq (org-element-property :type f) 'standard) nil)
-                      ((org-element-contents f))
-                      ;; Even if the contents are empty, we can not
-                      ;; return nil since that would eventually raise
-                      ;; the error.  Instead, return the equivalent
-                      ;; empty string.
-                      (t "")))
-                   info t)
+                  (let ((hashed (gethash (cons :element label) cache)))
+                    (when hashed
+                      (or (org-element-contents hashed)
+                         ;; Even if the contents are empty, we can not
+                         ;; return nil since that would eventually raise
+                         ;; the error.  Instead, return the equivalent
+                         ;; empty string.
+                          "")))
                  cache)
         (error "Definition not found for footnote %s" label))))))