I am trying to extend a tool that looks at files, searching for certain patterns. The tool is in perl and makes copious use of regular expressions. I came across a new pattern that has me scratching my head. I am trying to match a certain expression e that can have more than one definition ( shown in much simplified form ):

1. e =~ u
2. e =~ uae
3. e =~ edefe
4. e =~ ebe
5. e =~ ec

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As you can see, all but the first are recursive matches. I could write the above as 

e =~ u|uae|edefe|ebe|ec

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Here is what I have so far: if I had only 1 and 2 from above, I could write the combination of 1 and 2 as

e =~ u(?:au)*

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Likewise, for 1 and 3, I could write

e =~ udufu

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For 1 and 4, I would have

e =~ ubu

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and for 1 and 5, I would have

e =~ uc

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To go further, I would have to combine more than two together, and I think it could get horrifyingly complex. Is there a way to tackle a problem like this with dynamic regexes, or is there a method for substituting the above together?

I have perl 5.6, so I am slightly limited on what I can do. I do not know dynamic regexes well enough to frame the above with those. I cannot use CPAN or anything other than the screwdriver I have.

In reply to When the only tool you have is a screwdriver... by ExReg

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