[elpa] externals/auctex 5017391 10/27: Update region extension in font-latex.el

[Tassilo Horn]

branch: externals/auctex
commit 5017391b725ac1b9cca2ed216eee6d9af18d8248
Author: Ikumi Keita <ikumi@ikumi.que.jp>
Commit: Ikumi Keita <ikumi@ikumi.que.jp>

    Update region extension in font-latex.el
    
    * font-latex.el (font-latex--updated-region-end): New variable to
    record the end of the region that fontification actually took place.
    (font-latex-fontify-region): New function to utilize it.
    (font-latex-setup): Assign it to `font-lock-fontify-region-function'.
    (font-latex-match-math-env): Search closing tag beyond limit honoring
    `font-latex-multiline-boundary'.
    Use new variable.
    (font-latex-match-math-envII):
    (font-latex-match-dollar-math):
    Use new variable.
---
 font-latex.el | 81 ++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 53 insertions(+), 28 deletions(-)

diff --git a/font-latex.el b/font-latex.el
index d2f0064..14d64c6 100644
--- a/font-latex.el
+++ b/font-latex.el
@@ -1254,6 +1254,8 @@ triggers Font Lock to recognize the change."
            nil nil ,font-latex-syntax-alist nil))
        (variables
         '((font-lock-mark-block-function . mark-paragraph)
+          (font-lock-fontify-region-function
+           . font-latex-fontify-region)
           (font-lock-unfontify-region-function
            . font-latex-unfontify-region)
            (font-lock-extend-region-functions
@@ -1309,6 +1311,25 @@ If SYNTACTIC-KWS is non-nil, also update
             prettify-symbols--keywords)
     (font-lock-add-keywords nil prettify-symbols--keywords)))
 
+(defvar font-latex--updated-region-end nil
+;; During hilighting of math expression, matched range sometimes exceeds
+;; the given end limit. So record the actual end in this variable to
+;; notify the font lock machinery.
+;; Initialized at each font lock operation to the end limit of font lock
+;; range. Match function of math expression should do the following two if
+;; the end of the actual match goes beyond the value of this variable:
+;; 1. Apply `font-lock-unfontify-region' between the value of this variable
+;;    and the end of the actual match.
+;; 2. Update this variable to the end of the actual match.
+;; See implementation of `font-latex-match-math-env' for actual usage.
+  "Record the end of fontification.")
+(defun font-latex-fontify-region (beg end &optional verbose)
+  "Fontify region from BEG to END.
+Take care when the actually fonfified region was extended beyond END."
+  (setq font-latex--updated-region-end end)
+  (font-lock-default-fontify-region beg end verbose)
+  `(jit-lock-bounds ,beg . ,font-latex--updated-region-end))
+
 ;; Copy and adaption of `tex-font-lock-unfontify-region' from
 ;; tex-mode.el in GNU Emacs on 2004-08-04.
 ;; (XEmacs passes a third argument to the function.)
@@ -1712,10 +1733,16 @@ Used for patterns like:
          (if (and (re-search-forward (concat "[^\\]\\(?:\\\\\\\\\\)*\\("
                                              (regexp-quote open-tag) "\\|"
                                              (regexp-quote close-tag) "\\)")
-                                     limit 'move)
+                                     (+ limit font-latex-multiline-boundary)
+                                     'move)
                   (string= (match-string 1) close-tag))
              ;; Found closing tag.
-             (store-match-data (list beg beg beg (point)))
+             (let ((p (point)))
+               ;; If the closing tag is beyond `limit', take care of it.
+               (when (< font-latex--updated-region-end p)
+                 (font-lock-unfontify-region font-latex--updated-region-end p)
+                 (setq font-latex--updated-region-end p))
+               (store-match-data (list beg beg beg p)))
            ;; Did not find closing tag.
            (goto-char (+ beg 2))
            (store-match-data (list beg (point) (point) (point))))
@@ -1774,10 +1801,12 @@ The \\begin{equation} incl. arguments in the same line 
and
                                      (buffer-substring-no-properties
                                       (match-beginning 1)
                                       (match-end 2))))
-                            ;; XXX: Should this rather be done by
-                            ;; extending the region to be fontified?
                             (+ limit font-latex-multiline-boundary) 'move)
-         (setq end (match-beginning 0))
+         (progn
+           (setq end (match-beginning 0))
+           (when (< font-latex--updated-region-end end)
+             (font-lock-unfontify-region font-latex--updated-region-end end)
+             (setq font-latex--updated-region-end end)))
        (goto-char beg)
        (setq end beg))
       (store-match-data (list beg end))
@@ -1817,29 +1846,25 @@ The \\begin{equation} incl. arguments in the same line 
and
              num (skip-chars-forward "$" limit))
        ;; If those are three or more consecutive $, ignore them and
        ;; search again.
-       (when (< num 3)
-         (if ;; Let's find the same number of live dollar signs.
-             (font-latex-find-dollar-math limit num)
-             ;; Found.
-             (progn
-               (forward-char num)
-               (set-match-data (list beg (point)))
-               (throw 'match t))
-           ;; Not found. It means that there was opening "$" or
-           ;; "$$", but we can't find the corresponding close tag
-           ;; until LIMIT. Then it is either
-           ;; (1) The math expression continues to the next line, or
-           ;; (2) The buffer has unclosed "$" or "$$".
-           ;; Regard the former case as a positive match because
-           ;; experiments tends to imply that's more robust despite
-           ;; of frequent false positives produced during editing.
-           ;; N.B. It is ensured that LIMIT doesn't fall just
-           ;; inside single "$$" because
-           ;; `font-lock-extend-region-functions' takes care of it.
-           (if (eobp)
-               (throw 'match nil)
-             (set-match-data (list beg (point)))
-             (throw 'match t))))))))
+       (if (< num 3)
+           (if ;; Let's find the same number of live dollar signs.
+               (font-latex-find-dollar-math
+                ;; Hope that limit+font-latex-multiline-boundary
+                ;; doesn't fall just inside single "$$".
+                (+ limit font-latex-multiline-boundary) num)
+               ;; Found.
+               (progn
+                 (forward-char num)
+                 (let ((p (point)))
+                   (when (< font-latex--updated-region-end p)
+                     (font-lock-unfontify-region
+                      font-latex--updated-region-end p)
+                     (setq font-latex--updated-region-end p))
+                   (set-match-data (list beg p)))
+                 (throw 'match t))
+             ;; Not found.
+             ;; That $ or $$ is probably unclosed in the buffer.
+             (throw 'match nil)))))))
 
 (defun font-latex-find-dollar-math (limit &optional num)
   "Find dollar sign(s) before LIMIT.