Consider this (overly simplified) issue. I have a string, that contains in it an optional "list" of foos. Each foo has a recognizeable and distinct pattern, and of course there are many different specific foos. I want to see if my list of foos contains a certain specific foos. This problem must be solved with a regex (for other reasons). Example: A foo is a one letter an one number. They are separated by by one or more spaces. The list is preceded by a list name and is separated from the list in the "usual fashion".

Example input: bar a2 b2 c3 d3 d4 a1 f2 f3

I want the regex to be true if my list of foos contains d4 and b2. 
$_ = /^\w+		# matches list name
	(?:
	\s+
	[A-Za-z]\d
	)*
$/x
will match a list of foos with it's label.

But, I need a way to match specific foos in any place in any order insided the pattern. Is this possible? How? Thanks.

In reply to Set theory in regexs by dcorbin

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