Hi. I need to get the return data from a Parse::RecDescent parse tree created with the autotree directive.

Below is an example based on the article Parse::RecDescent Tutorial

The visitor function below seems to work. $AUTOLOAD instead of the switch statement would also be interesting.

But I'm wondering, is it really that simple? Or have I overlooked something?

Thanks. 

use strict;
use warnings;

use Parse::RecDescent;
use Switch;
use Scalar::Util 'blessed';

my $grammar = q(
    <autotree>
    
    startrule :
            day month date

    day :
            "Sat" | "Sun" | "Mon" | "Tue" | "Wed" | "Thu" | "Fri"

    month :
            "Jan" | "Feb" | "Mar" | "Apr" | "May" | "Jun" |
            "Jul" | "Aug" | "Sep" | "Oct" | "Nov" | "Dec"

    date:
            /\d+/
);

my $parser = Parse::RecDescent->new($grammar);

my $tree = $parser->startrule("Thu Mar 31");

visit($tree);

sub visit {
    my ($v) = @_;

    if ( blessed($v) ) {
        switch ( ref($v) ) {
            case "date" {
                print "The date is: ", $v->{__VALUE__}, "\n";
            }
            case "month" {
                print "The month is: ", $v->{__VALUE__}, "\n";
            }
        }
        foreach my $key ( keys %$v ) {
            visit( $v->{$key} );
        }
    }
}

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In reply to Parse::RecDescent autotree visitor by Sigil

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