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I'm trying to munge a simple grammar with a perl regex (note this isn’t intended for production use, just a quick analysis for providing editor hints/completions). For instance, my $GRAMMAR = qr{(?(DEFINE) (?<expr> $ (?&expr) $ | (?&number) | (?&var) | (?&expr) (?&op) (?&expr) ) (?<number> \d++ ) (?<var> [a-z]++ ) (?<op> [-+*/] ) )}x; I would like to be able to run this as $expr =~ /$GRAMMAR(?&expr)/; and then access all the variable names. However, according to perlre , Note that capture groups matched inside of recursion are not accessible after the recursion returns, so the extra layer of capturing groups is necessary. Thus $+{NAME_PAT} would not be defined even though $+{NAME} would be. So apparently this is not possible. I could try using a (?{ code }) block to save variable names to a hash, but this doesn't respect backtracking (i.e. the assignment’s side effect persists even if the variable is backtracked past). Is there any way to get everything captured by a given named capture group, including recursive matches? Or do I need to manually dig through the individual pieces (and thus duplicate all the patterns)?

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