[PATCH] Add support for $…$ latex fragments followed by a dash

["Sébastien Miquel" <sebastien.miquel@posteo.eu>]

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Hi,

The attached patch adds support for $…$ latex fragments followed by a
dash, such as $n$-th.

This pattern is quite common, and the issue was mentionned by Rudolf
Adamkovič, here: https://list.orgmode.org/m2mtjvefrf.fsf@me.com/.

This extension of the syntax doesn't conflict with the use of $'s in
table formulas, or for currency, AFAICT.

Regards,

-- 
Sébastien Miquel

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From b023fff129a5cc3b1f12b9f170f2e018dc34d237 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Miquel?= <sebastien.miquel@posteo.eu>
Date: Sun, 23 Jan 2022 13:28:03 +0100
Subject: [PATCH] =?UTF-8?q?org-element:=20Support=20$=E2=80=A6$=20LaTeX=20?=
 =?UTF-8?q?fragments=20followed=20by=20a=20dash?=
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

* lisp/org-element.el (org-element-latex-fragment-parser):
* lisp/org.el (org-latex-regexps): Allow a dash right after a
$…$ fragment.
* testing/lisp/test-org-element.el (test-org-element/latex-fragment-parser):
Add test.

Allows such uses as `$n$-th' or `$n$-dimensional'.
---
 lisp/org-element.el              | 2 +-
 lisp/org.el                      | 4 ++--
 testing/lisp/test-org-element.el | 4 ++++
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/lisp/org-element.el b/lisp/org-element.el
index b82475a14..40a604578 100644
--- a/lisp/org-element.el
+++ b/lisp/org-element.el
@@ -3416,7 +3416,7 @@ Assume point is at the beginning of the LaTeX fragment."
 		     (not (memq (char-before (match-beginning 0))
 				'(?\s ?\t ?\n ?, ?.)))
 		     (looking-at-p
-		      "\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|'\\|$\\)")
+		      "\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|'\\|-\\|$\\)")
 		     (point)))))
 	     (post-blank
 	      (if (not after-fragment) (throw 'no-object nil)
diff --git a/lisp/org.el b/lisp/org.el
index 2d439cd05..3a164ee77 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -629,8 +629,8 @@ An entry can be toggled between COMMENT and normal with
   '(("begin" "^[ \t]*\\(\\\\begin{\\([a-zA-Z0-9\\*]+\\)[^\000]+?\\\\end{\\2}\\)" 1 t)
     ;; ("$" "\\([ \t(]\\|^\\)\\(\\(\\([$]\\)\\([^ \t\n,.$].*?\\(\n.*?\\)\\{0,5\\}[^ \t\n,.$]\\)\\4\\)\\)\\([ \t.,?;:'\")]\\|$\\)" 2 nil)
     ;; \000 in the following regex is needed for org-inside-LaTeX-fragment-p
-    ("$1" "\\([^$]\\|^\\)\\(\\$[^ \t\r\n,;.$]\\$\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|'\\|$\\)" 2 nil)
-    ("$"  "\\([^$]\\|^\\)\\(\\(\\$\\([^ \t\n,;.$][^$\n\r]*?\\(\n[^$\n\r]*?\\)\\{0,2\\}[^ \t\n,.$]\\)\\$\\)\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|'\\|$\\)" 2 nil)
+    ("$1" "\\([^$]\\|^\\)\\(\\$[^ \t\r\n,;.$]\\$\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|'\\|-\\|$\\)" 2 nil)
+    ("$"  "\\([^$]\\|^\\)\\(\\(\\$\\([^ \t\n,;.$][^$\n\r]*?\\(\n[^$\n\r]*?\\)\\{0,2\\}[^ \t\n,.$]\\)\\$\\)\\)\\(\\s.\\|\\s-\\|\\s(\\|\\s)\\|\\s\"\\|\000\\|'\\|-\\|$\\)" 2 nil)
     ("\\(" "\\\\([^\000]*?\\\\)" 0 nil)
     ("\\[" "\\\\\\[[^\000]*?\\\\\\]" 0 nil)
     ("$$" "\\$\\$[^\000]*?\\$\\$" 0 nil))
diff --git a/testing/lisp/test-org-element.el b/testing/lisp/test-org-element.el
index 6d7376a96..2055e3a7b 100644
--- a/testing/lisp/test-org-element.el
+++ b/testing/lisp/test-org-element.el
@@ -1776,6 +1776,10 @@ e^{i\\pi}+1=0
    (eq 'latex-fragment
        (org-test-with-temp-text "$a$'"
 	 (org-element-type (org-element-context)))))
+  (should
+   (eq 'latex-fragment
+       (org-test-with-temp-text "$a$-"
+	 (org-element-type (org-element-context)))))
   ;; Test forbidden characters inside $...$.
   (should-not
    (eq 'latex-fragment
-- 
2.34.1