Re: Radio links work only in small numbers

[Ihor Radchenko <yantar92@posteo.net>]

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Rudolf Adamkovič <salutis@me.com> writes:

> Greetings smart people!
>
> All [[link]]s in my notes perfectly match LEVEL-1 headings, so I figured
> that I may as well ask Org to make links for me.  So, I replaced all the
> ~4000 headings in my notes with radio <<<targets>>>.  However, Org now
> errors out with "Regular expression too big".
>
> Does anyone know how to overcome this limitation?  Or, perhaps someone
> has a patch in works that fixes it?  If so, please let me know!

This is C-level error emitted by Emacs' regexp engine.

Can you try the attached patch?

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From 53e6c067e4897c5b6c1ac8201e2dbc49baa9e6e8 Mon Sep 17 00:00:00 2001
Message-Id: <53e6c067e4897c5b6c1ac8201e2dbc49baa9e6e8.1671006575.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Wed, 14 Dec 2022 11:28:03 +0300
Subject: [PATCH] org-update-radio-target-regexp: Try to get a shorter regexp
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

* lisp/ol.el (org-update-radio-target-regexp): Use `regexp-opt' to
compact the resulting regexp as much as possible.  Otherwise, some
users hit regexp length limits when the number of radio targets
approaches thousands.

Reported-by: Rudolf Adamkovič <salutis@me.com>
Link: https://orgmode.org/list/m2lenax5m6.fsf@me.com
---
 lisp/ol.el | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/lisp/ol.el b/lisp/ol.el
index 3ae8f8875..51ee028e4 100644
--- a/lisp/ol.el
+++ b/lisp/ol.el
@@ -2065,13 +2065,11 @@ (defun org-update-radio-target-regexp ()
     (setq org-target-link-regexp
 	  (and targets
 	       (concat before-re
-		       (mapconcat
-			(lambda (x)
-			  (replace-regexp-in-string
-			   " +" "\\s-+" (regexp-quote x) t t))
-			targets
-			"\\|")
-		       after-re)))
+                       (replace-regexp-in-string
+                        " +" "\\s-+"
+                        (regexp-opt targets)
+                        nil t)
+                       after-re)))
     (unless (equal old-regexp org-target-link-regexp)
       ;; Clean-up cache.
       (let ((regexp (cond ((not old-regexp) org-target-link-regexp)
-- 
2.38.1


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-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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