Bdtjtk

In perl6 grammars, as explained here (note, the design documents are not guaranteed to be up-to-date as the implementation is finished), if an opening angle bracket is followed by an identifier then the construct is a call to a subrule, method or function.

If the character following the identifier is an opening paren, then it's a call to a method or function eg: <foo('bar')>. As explained further down the page, if the first char after the identifier is a space, then the rest of the string up to the closing angle will be interpreted as a regex argument to the method - to quote:

 <foo bar>

is more or less equivalent to

 <foo(/bar/)>

What's the proper way to use this feature? In my case, I'm parsing line oriented data and I'm trying to declare a rule that will instigate a seperate search on the current line being parsed:

#!/usr/bin/env perl6

# use Grammar::Tracer ;



grammar G {

    my $SOLpos = -1 ;   # Start-of-line pos



    regex TOP {  <line>+  }



    method SOLscan($regex) {

        # Start a new cursor

        my $cur = self."!cursor_start_cur"() ;



        # Set pos and from to start of the current line

        $cur.from($SOLpos) ;

        $cur.pos($SOLpos) ;



        # Run the given regex on the cursor

        $cur = $regex($cur) ;



        # If pos is >= 0, we found what we were looking for

        if $cur.pos >= 0 {

            $cur."!cursor_pass"(self.pos, 'SOLscan')

        }



        self

    }



    token line {

        { $SOLpos = self.pos ; say '$SOLpos = ' ~ $SOLpos }

        [

        || <word> <ws> 'two' { say 'matched two' }  <SOLscan w+> <ws> <word>

        || <word>+ %% <ws>    { say 'matched words' }

        ]

        n

    }



    token word  {  S+  }

    token ws    {  h+  }

}



my $mo = G.subparse: q:to/END/ ;

hello world

one two three

END

As it is, this code produces:

$ ./h.pl

$SOLpos = 0

matched words

$SOLpos = 12

matched two

Too many positionals passed; expected 1 argument but got 2

  in method SOLscan at ./h.pl line 14

  in regex line at ./h.pl line 32

  in regex TOP at ./h.pl line 7

  in block <unit> at ./h.pl line 41

$

Line 14 is $cur.from($SOLpos). If commented out, line 15 produces the same error. It appears as though .pos and .from are read only... (maybe :-)

Any ideas what the proper incantation is?
Note, any proposed solution can be a long way from what I've done here - all I'm really wanting to do is understand how the mechanism is supposed to be used.

It does not seem to be in the corresponding directory in roast, so that would make it a "Not Yet Implemented" feature, I'm afraid.