Perl 6 Rules reframe parsing along the lines you suggest. https://en.wikipedia.org/wiki/Perl_6_rules https://en.wikipedia.org/wiki/Perl_6_rules contains the gr

Perl 6 Rules reframe parsing along the lines you suggest. https://en.wikipedia.org/wiki/Perl_6_rules https://en.wikipedia.org/wiki/Perl_6_rules contains the grammar used to define Perl's sprintf string formatting notation: grammar Str::SprintfFormat { regex format_token { \%: <index>? <precision>? <modifier>? <directive> } token index { \d+ \$ } token precision { <flags>? <vector>? <precision_count> } token flags { <[\ +0\#\-]>+ } token precision_count { [ <[1-9]>\d* | \* ]? [ \. [ \d* | \* ] ]? } token vector { \*? v } token modifier { ll | <[lhmVqL]> } token directive { <[\%csduoxefgXEGbpniDUOF]> } } You could use these rules like so: if / <Str::SprintfFormat::format_token> / { ... } Perl 6 Rules unify PEGs, regexes, and closures -- "[a] rule used in this way is actually identical to the invocation of a subroutine with the extra semantics and side-effects of pattern matching (e.g., rule invocations can be backtracked)." Have you looked at Perl 6 Rules?