Perl6 grammars: match full line

I can see 2 problem in your Grammar here, the first one here is the token line, ^^ and $$ are anchor to start and end of line, howeve you can have new line in between. To illustrate, let's just use a simple regex, without Grammar first:

my $txt = q:to/EOS/;
    row 1
    row 2
    row 3
    EOS

if $txt ~~ m/^^.*$$/ {
    say "match";
    say $/;
}

Running that, the output is:

match
｢row 1
row 2
row 3｣

You see that the regex match more that what is desired, however the first problem is not there, it is because of ratcheting, matching with a token will not work:

my $txt = q:to/EOS/;
    row 1
    row 2
    row 3
    EOS

my regex r {^^.*$$};
if $txt ~~ &r {
    say "match regex";
    say $/;
} else {
    say "does not match regex";
}
my token t {^^.*$$};
if $txt ~~ &t {
    say "match token";
    say $/;
} else {
    say "does not match token";
}

Running that, the output is:

match regex
｢row 1
row 2
row 3｣
does not match token

I am not really sure why, but token and anchor $$ does not seems to work well together. But what you want instead is searching for everything except a newline, which is \N* The following grammar solve mostly your issue:

grammar sample {
    token TOP {<line>}
    token line {\N+}
}

However it only matches the first occurence, as you search for only one line, what you might want to do is searching for a line + an optional vertical whitespace (In your case, you have a new line at the end of your string, but i guess you would like to take the last line even if there is no new line at the end ), repeated several times:

my $txt = q:to/EOS/;
    row 1
    row 2
    row 3
    EOS

grammar sample {
    token TOP {[<line>\v?]*}
    token line {\N+}
}

my $match = sample.parse($txt);
for $match<line> -> $l {
    say $l;
}

Output of that script begin:

｢row 1｣
｢row 2｣
｢row 3｣

Also to help you using and debugging Grammar, 2 really usefull modules : Grammar::Tracer and Grammar::Debugger . Just include them at the beginning of the script. Tracer show a colorful tree of the matching done by your Grammar. Debugger allows you to see it matching step by step in real time.

Your original aproach can be made to work via

grammar sample {
    token TOP { <line>+ %% \n }
    token line { ^^ .*? $$ }
}

Personally, I would not try to anchor line and use \N instead as already suggested.