TeX \mathXY folding, account for deceptive codepts

config.org

@@ -6478,7 +6478,50 @@ Let's enhance ~TeX-fold-math~ a bit
 (defun string-offset-roman-chars (offset word)
   "Shift the codepoint of each charachter in WORD by OFFSET with an extra -6 shift if the letter is lowercase"
   (apply 'string
-         (mapcar (lambda (c) (+ (if (>= c 97) (- c 6) c) offset)) word)))
+         (mapcar (lambda (c)
+                   (string-offset-apply-roman-char-exceptions
+                    (+ (if (>= c 97) (- c 6) c) offset)))
+                 word)))
+
+(defvar string-offset-roman-char-exceptions
+  '(;; lowercase serif
+    (119892 .  8462) ; ℎ
+    ;; lowercase caligraphic
+    (119994 . 8495) ; ℯ
+    (119996 . 8458) ; ℊ
+    (120004 . 8500) ; ℴ
+    ;; caligraphic
+    (119965 . 8492) ; ℬ
+    (119968 . 8496) ; ℰ
+    (119969 . 8497) ; ℱ
+    (119971 . 8459) ; ℋ
+    (119972 . 8464) ; ℐ
+    (119975 . 8466) ; ℒ
+    (119976 . 8499) ; ℳ
+    (119981 . 8475) ; ℛ
+    ;; fraktur
+    (120070 . 8493) ; ℭ
+    (120075 . 8460) ; ℌ
+    (120076 . 8465) ; ℑ
+    (120085 . 8476) ; ℜ
+    (120092 . 8488) ; ℨ
+    ;; blackboard
+    (120122 . 8450) ; ℂ
+    (120127 . 8461) ; ℍ
+    (120133 . 8469) ; ℕ
+    (120135 . 8473) ; ℙ
+    (120136 . 8474) ; ℚ
+    (120137 . 8477) ; ℝ
+    (120145 . 8484) ; ℤ
+    )
+  "An alist of deceptive codepoints, and then where the glyph actually resides.")
+
+(defun string-offset-apply-roman-char-exceptions (char)
+  "Sometimes the codepoint doesn't contain the char you expect.
+Such special cases should be remapped to another value, as given in `string-offset-roman-char-exceptions'."
+  (if (assoc char string-offset-roman-char-exceptions)
+      (cdr (assoc char string-offset-roman-char-exceptions))
+    char))
 
 (defun TeX-fold-parenthesize-as-neccesary (tokens &optional suppress-left suppress-right)
   "Add ❪ ❫ parenthesis as if multiple LaTeX tokens appear to be present"