[nongnu] elpa/rainbow-delimiters 1305bca532 087/188: Use comment-search-forward to see if a delimiter starts a comment.

[ELPA Syncer]

branch: elpa/rainbow-delimiters
commit 1305bca532f482f248814f0b918b0989a6c12dd4
Author: Fanael Linithien <fanael4@gmail.com>
Commit: Fanael Linithien <fanael4@gmail.com>

    Use comment-search-forward to see if a delimiter starts a comment.
    
    (looking-at comment-start-skip) is not always enough, because some
    major modes set `comment-start-skip' to not exactly what we expect.
    
    Fixes #35.
---
 rainbow-delimiters.el | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/rainbow-delimiters.el b/rainbow-delimiters.el
index 940ee1bb30..0e8a08b267 100644
--- a/rainbow-delimiters.el
+++ b/rainbow-delimiters.el
@@ -96,6 +96,7 @@
 ;; - Intelligent support for other languages: Ruby, LaTeX tags, et al.
 
 ;;; Code:
+(require 'newcomment)
 
 ;;; Customize interface:
 
@@ -437,8 +438,19 @@ Returns t if char at loc meets one of the following 
conditions:
    (nth 4 ppss)                ; inside comment?
    (save-excursion             ; starting a comment?
      (goto-char loc)
-     (let ((inhibit-changing-match-data t))
-       (looking-at comment-start-skip)))
+     (and
+      ;; Fast path: if this test fails, it's not a comment, and we avoid a
+      ;; costly `comment-search-forward' call.
+      (let ((inhibit-changing-match-data t))
+        (looking-at comment-start-skip))
+      ;; Some major modes set `comment-start-skip' to not exactly what we
+      ;; expect, catching more than actual comments. Use
+      ;; `comment-search-forward' to see if it's really a comment.
+      ;; NOTE: is lookahead of five characters enough for all languages? I hope
+      ;; there's no language with 6-character comment delimiters.
+      (save-match-data
+        (let ((comment-start-pos (comment-search-forward (min (+ 5 loc) 
(point-max)) t)))
+          (and comment-start-pos (= loc comment-start-pos))))))
    (and rainbow-delimiters-escaped-char-predicate
         (funcall rainbow-delimiters-escaped-char-predicate loc))))
 
@@ -531,6 +543,8 @@ Used by font-lock for dynamic highlighting."
 
 (defun rainbow-delimiters-mode-turn-on ()
   "Set up `rainbow-delimiters-mode'."
+  ;; Necessary for our use of `comment-search-forward'.
+  (comment-normalize-vars t)
   ;; Flush the ppss cache now in case there's something left in there.
   (setq rainbow-delimiters-parse-partial-sexp-cache nil)
   (add-hook 'before-change-functions 
'rainbow-delimiters-syntax-ppss-flush-cache t t)