In How can I pass arguments to a Perl 6 grammar? I passed an argument to a rule as part of a submerse. I was wondering how I'd do that completely inside a grammar. Suppose I had something like:
grammar TryIt {
rule TOP { \d+ <stuff> }
rule stuff ($count) { <[ \S A..Z ]>{$count} }
}
my $match = TryIt.parse: "123 ABCD";
say $match;
How do I pass an argument from TOP to stuff? I didn't find any examples and various guesses about parens near stuff didn't work.
These forms both work:
<stuff(...)>
<stuff: ...>
Not sure where they're listed in the user documentation, but the S05: Regexes and Rules design document has a section on them.
Note that inside a rule, backreferences like $0 and $/ are only guaranteed to be available after a sequence point, e.g the opening brace of a block. An empty block {} works.
Example:
grammar TryIt {
token TOP { (\d+) \s {} <stuff($0)> .* }
token stuff ($count) { <[ A..Z ]> ** {$count} }
}
say TryIt.subparse: "3 ABCDEFG";
Output:
｢3 ABCDEFG｣
0 => ｢3｣
stuff => ｢ABC｣
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