[elpa] externals/auctex 4d58d7d 09/30: Don't extend font lock region too eagerly (bug#42267)

[Tassilo Horn]

branch: externals/auctex
commit 4d58d7d1abd84feb7d975da3c9571a884756ff37
Author: Ikumi Keita <ikumi@ikumi.que.jp>
Commit: Ikumi Keita <ikumi@ikumi.que.jp>

    Don't extend font lock region too eagerly (bug#42267)
    
    * font-latex.el (font-latex-extend-region-backwards-quotation): If
    there is no matching open quote, don't extend the font lock region.
---
 font-latex.el | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/font-latex.el b/font-latex.el
index d7d26fa..09a6feb 100644
--- a/font-latex.el
+++ b/font-latex.el
@@ -2066,19 +2066,33 @@ set to french, and >>german<< (and 8-bit) are used if 
set to german."
                    (setq opening-quote (car elt))
                    (throw 'found nil))))
              ;; Find opening quote taking nested quotes into account.
-             (while (progn
-                      (re-search-backward (concat opening-quote "\\|"
-                                                  closing-quote)
-                                          point-of-surrender 'move)
-                      (when (and (> (point) point-of-surrender)
-                                 (not (bobp)))
-                        (if (string= (match-string 0) closing-quote)
-                            (setq nest-count (1+ nest-count))
-                          (when (/= nest-count 0)
-                            (setq nest-count (1- nest-count)))))))
-             (when (< (point) font-lock-beg)
-                (setq font-lock-beg (point))
-               (throw 'extend t)))))))))
+             (while (and (re-search-backward (concat opening-quote "\\|"
+                                                     closing-quote)
+                                             point-of-surrender t)
+                         ;; Found quotes before point-of-surrender.
+                         (cond ((string= (match-string 0) closing-quote)
+                                ;; Encountered another closing quote.
+                                ;; Increase nest-count and continue
+                                ;; the inner loop.
+                                (setq nest-count (1+ nest-count)))
+                               ;; Found an opening quote.
+                               ((/= nest-count 0)
+                                ;; If in nest, decrease nest-count
+                                ;; and continue the inner loop.
+                                (setq nest-count (1- nest-count)))
+                               ;; Else we arrived at the opening quote
+                               ;; matching with the closing quote found
+                               ;; in the outer loop.
+                               ((< (point) font-lock-beg)
+                                ;; If that opening quote locates
+                                ;; before `font-lock-beg', break the
+                                ;; outer loop and extend the region.
+                                (setq font-lock-beg (point))
+                                (throw 'extend t))
+                               (t
+                                ;; Else terminate the inner loop and
+                                ;; continue the outer loop.
+                                nil)))))))))))
 
 (defun font-latex-match-script (limit)
   "Match subscript and superscript patterns up to LIMIT."