ox-latex: Do not generate nested sub/superscripts

* lisp/ox-latex.el (org-latex--wrap-latex-math-block): Do not wrap
  consecutive sub or super-scripts within the same block.

Reported-by: Scott Otterson <scotto@sharpleaf.org>
<http://permalink.gmane.org/gmane.emacs.orgmode/110589>

1 files changed, 16 insertions, 14 deletions

diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
index aecbb32..4d65922 100644
--- a/lisp/ox-latex.el
+++ b/lisp/ox-latex.el
@@ -2698,22 +2698,23 @@ channel."
 DATA is a parse tree or a secondary string.  INFO is a plist
 containing export options.  Modify DATA by side-effect and return it."
   (let ((valid-object-p
-	 ;; Non-nil when OBJ can be added to the latex math block.
-	 (lambda (obj)
+	 ;; Non-nil when OBJ can be added to the latex math block B.
+	 (lambda (obj b)
 	   (pcase (org-element-type obj)
 	     (`entity (org-element-property :latex-math-p obj))
 	     (`latex-fragment
 	      (let ((value (org-element-property :value obj)))
 		(or (string-prefix-p "\\(" value)
 		    (string-match-p "\\`\\$[^$]" value))))
-	     ((or `subscript `superscript) t)))))
+	     ((and type (or `subscript `superscript))
+	      (not (org-element-map b type #'identity info t)))))))
     (org-element-map data '(entity latex-fragment subscript superscript)
       (lambda (object)
 	;; Skip objects already wrapped.
 	(when (and (not (eq (org-element-type
 			     (org-element-property :parent object))
 			    'latex-math-block))
-		   (funcall valid-object-p object))
+		   (funcall valid-object-p object nil))
 	  (let ((math-block (list 'latex-math-block nil))
 		(next-elements (org-export-get-next-element object info t))
 		(last object))
@@ -2725,16 +2726,17 @@ containing export options.  Modify DATA by side-effect and return it."
 	      ;; MATH-BLOCK swallows consecutive math objects.
 	      (catch 'exit
 		(dolist (next next-elements)
-		  (if (not (funcall valid-object-p next)) (throw 'exit nil)
-		    (org-element-extract-element next)
-		    (org-element-adopt-elements math-block next)
-		    ;; Eschew the case: \beta$x$ -> \(\betax\).
-		    (unless (memq (org-element-type next)
-				  '(subscript superscript))
-		      (org-element-put-property last :post-blank 1))
-		    (setq last next)
-		    (when (> (or (org-element-property :post-blank next) 0) 0)
-		      (throw 'exit nil))))))
+		  (unless (funcall valid-object-p next math-block)
+		    (throw 'exit nil))
+		  (org-element-extract-element next)
+		  (org-element-adopt-elements math-block next)
+		  ;; Eschew the case: \beta$x$ -> \(\betax\).
+		  (unless (memq (org-element-type next)
+				'(subscript superscript))
+		    (org-element-put-property last :post-blank 1))
+		  (setq last next)
+		  (when (> (or (org-element-property :post-blank next) 0) 0)
+		    (throw 'exit nil)))))
 	    (org-element-put-property
 	     math-block :post-blank (org-element-property :post-blank last)))))
       info nil '(subscript superscript latex-math-block) t)