Fix infinite loop in swift-mode:syntax-propertize:scan

Fix #192

Author: taku0

swift-mode-lexer.el

@@ -251,7 +251,7 @@ Intended for `syntax-propertize-function'."
  ((swift-mode:chunk:comment-p chunk)
  (goto-char (swift-mode:chunk:start chunk))
  (setq comment-start (point))
- (forward-comment 1)
+ (swift-mode:forward-comment 1 end)
  (put-text-property comment-start (point) 'swift-mode:comment t))))
  (swift-mode:syntax-propertize:scan end 0))
 
@@ -304,7 +304,7 @@ stops where the level becomes zero."
  ;; Comments
  ((memq (char-after) '(?/ ?*))
  (goto-char start)
- (forward-comment 1)
+ (swift-mode:forward-comment 1 end)
  (put-text-property start (point) 'swift-mode:comment t))
 
  ;; Operators
@@ -323,6 +323,62 @@ stops where the level becomes zero."
  (goto-char end))
  found-matching-parenthesis))
 
+(defun swift-mode:forward-comment (count &optional end)
+ "Move point after spaces and COUNT comments.
+
+If END is given, do not move beyond END.
+
+COUNT must be positive.
+
+Multiline comments can be nested.
+
+If the comment is not closed, move to END if given, or `point-max' if it
+is nil.
+
+This function doesn't depend on the syntax tables, so that it works in
+`swift-mode:syntax-propertize'."
+ (while (< 0 count)
+ (skip-chars-forward "\s\t\n")
+ (cond
+ ;; Single line comment
+ ((and (eq (char-after) ?/)
+ (eq (char-after (1+ (point))) ?/))
+ (forward-line))
+
+ ;; Multiline comment
+ ((and (eq (char-after) ?/)
+ (eq (char-after (1+ (point))) ?*))
+ (swift-mode:forward-multiline-comment (or end (point-max))))
+
+ ;; Not a comment
+ (t
+ (setq count 1)))
+ (setq count (1- count))))
+
+(defun swift-mode:forward-multiline-comment (end)
+ "Move point after a multiline comment.
+
+Assuming the point is just before a multiline comment.
+
+Do not move beyond END.
+
+Multiline comments can be nested.
+
+If the comment is not closed, move to END."
+ (forward-char 2)
+ (let ((pattern (mapconcat #'regexp-quote '("/*" "*/") "\\|"))
+ (nesting-level 1))
+ (while (and (< 0 nesting-level)
+ (< (point) end)
+ (search-forward-regexp pattern end t))
+ (if (eq (char-before) ?*)
+ (setq nesting-level (1+ nesting-level))
+ (setq nesting-level (1- nesting-level))))
+ (when (or (and (not (zerop nesting-level))
+ (< (point) end))
+ (< end (point)))
+ (goto-char end))))
+
 (defun swift-mode:put-syntax-multiline-property (start end)
  "Put `syntax-multiline` text propery from START to END.