The behaviour you are seeing is caused by the fact that $1 and friends are only overwritten by a successfull match or substitution that has backreferences.

So your code says check this expressions against $1, if that matched then and only then will $1, $2 & $3 be given the new values. If it didn't match, then there is no statement to overwrite $1, so your that your else clause is checking the same value of $1.

Nuance

In reply to RE: Scope of regular expression variables by nuance
in thread Scope of regular expression variables by FauxPasIII

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