(buffer-substring-no-properties (match-beginning num)
(match-end num)))))
+
+(defun match-substitute-replacement (replacement
+ &optional fixedcase literal string subexp)
+ "Return REPLACEMENT as it will be inserted by `replace-match'.
+In other words, all back-references in the form `\\&' and `\\N'
+are substituted with actual strings matched by the last search.
+Optional FIXEDCASE, LITERAL, STRING and SUBEXP have the same
+meaning as for `replace-match'."
+ (let ((match (match-string 0 string)))
+ (save-match-data
+ (set-match-data (mapcar (lambda (x)
+ (if (numberp x)
+ (- x (match-beginning 0))
+ x))
+ (match-data t)))
+ (replace-match replacement fixedcase literal match subexp))))
+
+
(defun looking-back (regexp &optional limit greedy)
"Return non-nil if text before point matches regular expression REGEXP.
Like `looking-at' except matches before point, and is slower.