I'm somewhat surprised by the amount of confusion in this thread, and am starting to wonder if somehow it is me that is being stupid.

From the first paragraph I discern that BernieC has a template, and from that wants to derive a regular expression that will match things according to the pattern described by the template.

The second paragraph shows that from the template "abcdefa" the regular expression should look something like /(.)?????\1/, and he wants help filling in the middle part, where each '?' should be replaced by a regexp fragment that ensures it represents a distinct letter.

So the template forms a pattern that inputs should match, where each letter in the template should match some arbitrary character of the input - but the same template letter should match the same character each time, and distinct template letters should always match distinct characters.

Thus an input like "Mississippi" would match a template "abccbccbddb". Given the template "abccbccbddb" he wants to generate a regular expression that will match an input like "Mississippi".

That's what I get from reading the OP.

In reply to Re: Nonrepeating characters in an RE by hv
in thread Nonrepeating characters in an RE by BernieC

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