How to combine these two regular expressions

[Cecil Westerhof]

I was asked by someone for a regular expression that could combine
several search patterns, so that a file only needs to be scanned ones
and not several times. I was partly successful, but I still need two
passes.

I now have the following code:
(defun dcbl-search-heading ()
(interactive)
(re-search-forward "\\(.
\\)\\(

\\)\\(.+
\\)\\(
?.+
\\)" nil t)
(replace-match "\\1
#heading#
\\4"))

(defun dcbl-search-heading2 ()
(interactive)
(re-search-forward "\\(.
\\)\\(
\\)\\(.+
\\)\\(\\\(.+
\\\)+\\)" nil t)
(replace-match "\\1
#heading#
\\4"))

Is there a way to combine those regular expressions to one?

By the way, if the used expressions could be optimised, let me know. I
do not make them often, thus maybe I do things sub-optimal here.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

[Jambunathan K]

You should provide a human-readable description of what the regexes are
trying to do. Have you tried:

C-h f regexp-opt RET

[Doug Lewan]

The most common way to "combine" two regular expressions is the form "\\(RE1\\|RE2\\)".

I usually do this with variables (concat "\\(" re-1 "\\|" re-2 "\\)").

There's also the form "\\(?:...\\)" if you don't care about match data or "\\(?N:...\\)" if you care very much about it. (N is an integer and forces this match to become match number N.)

I hope this helps.

,Doug