[mkching]

If I came across the code in the original post, I would be confused as to what the Or operator applied to. With a regexp, the parenthesis make this clear.

I would also assume that Exactly(1).Of(".") was meant to match a literal ".". In a PCRE, you can surround a section with \Q...\E to force literal interpretation, but I believe in .NET you would need to call Regexp.Escape.

The overall concept is not a terrible idea, but you should probably become a little more familiar with regexps before trying to write a library that creates them. While some things in the sample seem a natural product of being code generated (e.g. "@{1,1}" instead of simply "@"), the use of "(?:" in many places is simply not needed.