bug#41559: texmathp reports false negatives

[Ikumi Keita]

Hi Timothy,

>>>>> TEC <tec@tecosaur.com> writes:
> That's great to hear. Thank you very much for taking a look at this.
> With the new org-edit-special for inline LaTeX fragments, having this
> work smoothly would be marvelous :)

> If you'd also be willing to check out the
> \[
>    a
> \]
> case as well, that would be similarly appriciated.

I installed a fix in the git repo. You can try it out with the following
patch.

Regards,
Ikumi Keita

diff --git a/texmathp.el b/texmathp.el
index ba5aba39..723623bc 100644
--- a/texmathp.el
+++ b/texmathp.el
@@ -185,13 +185,11 @@ customize (customize calls it when setting the variable)."
                      ((memq type '(sw-toggle))      'togglers)))
       (set var (cons (car entry) (symbol-value var))))
     (setq texmathp-onoff-regexp
-         (concat "[^\\\\]\\("
-                 (mapconcat 'regexp-quote switches "\\|")
-                 "\\)")
+         (concat "\\(?:[^\\\\]\\|\\`\\)"
+                 (regexp-opt switches t))
          texmathp-toggle-regexp
-         (concat "\\([^\\\\\\$]\\|\\`\\)\\("
-                 (mapconcat 'regexp-quote togglers "\\|")
-                 "\\)"))))
+         (concat "\\([^\\\\\\$]\\|\\`\\)"
+                 (regexp-opt togglers t)))))
 
 (defcustom texmathp-tex-commands nil
   "List of environments and macros influencing (La)TeX math mode.
@@ -287,14 +285,17 @@ See the variable `texmathp-tex-commands' about which 
commands are checked."
 
     ;; Select the nearer match
     (and env-match (setq match env-match))
-    (and mac-match (> (cdr mac-match) (cdr match)) (setq match mac-match))
+    ;; Use `>=' instead of `>' in case called inside \ensuremath{..}
+    ;; beginning just at (point-min).
+    (and mac-match (>= (cdr mac-match) (cdr match)) (setq match mac-match))
     (setq math-on (memq (nth 1 (assoc (car match) texmathp-tex-commands1))
                        '(env-on arg-on)))
 
     ;; Check for switches
     (and (not math-on)
         (setq sw-match (texmathp-match-switch bound))
-        (> (cdr sw-match) (cdr match))
+        ;; Use `>=' instead of `>' by similar reason as above. (bug#41559)
+        (>= (cdr sw-match) (cdr match))
         (eq (nth 1 (assoc (car sw-match) texmathp-tex-commands1)) 'sw-on)
         (setq match sw-match math-on t))