# https://perlmonks.org/index.pl?node_id=11132953
use strict;
use warnings;
use Data::Dump qw/pp dd/;

my $obj = "CiscoService";

while (<DATA>) {
    chomp;
    my ($indent,$data) = /^(\s*)(.*)$/;
    my ($call, @args) = split/\s+/, $data;
    $call =~ s/^!$/__out__/;
    $call =~ s/-/_/g;

    if ( my $meth = $obj->can($call) ) {
        $obj =  $meth->( $obj, length($indent),@args)
    } else {
        warn "<$call> not impemented";
    }
}

package CiscoService;
use Data::Dump qw/pp dd/;

sub service {
    my ($self,$indent,@args) = @_;
    return bless {__head__ => \@args, sub=>{} },__PACKAGE__;
}

sub description {
    my ($self,$indent,@args) = @_;
    $self->{sub}{description} = \@args;
    return $self;
}

sub service_policy {
    my ($self,$indent,@args) = @_;
    $self->{sub}{"service-policy"} = \@args;
    return $self;
}

sub encapsulation {
    my ($self,$indent,@args) = @_;
    $self->{sub}{encapsulation} = \@args;
    return $self;
}
sub rewrite {
    my ($self,$indent,@args) = @_;
    $self->{sub}{rewrite} = \@args;
    return $self;
}
sub xconnect {
    my ($self,$indent,@args) = @_;
    $self->{sub}{xconnect} = {head =>\@args, sub=>{}};
    return $self;
}

sub mtu {
    my ($self,$indent,@args) = @_;
    $self->{sub}{xconnect}{sub}{mtu} = \@args;
    return $self;
}

sub __out__ {
    my ($self,$indent,@args) = @_;
    pp $self;
    return "CiscoService";
}


package main;

__DATA__
 service instance 20 ethernet
  description Internal site
  encapsulation dot1q 17
  rewrite ingress tag pop 1 symmetric
  xconnect 192.168.51.20 838969735 encapsulation mpls
   mtu 9202
 !
 service instance 21 ethernet
  description Client 1 important
  encapsulation dot1q 18
  rewrite ingress tag pop 1 symmetric
  xconnect 192.168.51.21 838969736 encapsulation mpls
   mtu 9202
 !
 service instance 22 ethernet
  description Client other 2
  encapsulation dot1q 22
  rewrite ingress tag pop 1 symmetric
  xconnect 192.168.56.22 838925386 encapsulation mpls
   mtu 9202
 !
 service instance 23 ethernet
  description Client name with fun stuff
  encapsulation dot1q 3200 second-dot1q 5
  rewrite ingress tag pop 2 symmetric
  service-policy input CoS_222_333_23
  xconnect 192.168.56.23 571125465 encapsulation mpls
   mtu 9202
 !
 service instance 24 ethernet
  description Client - not as important
  encapsulation dot1q 3200 second-dot1q 6
  rewrite ingress tag pop 2 symmetric
  service-policy input 222_444_24
  xconnect 192.168.56.24 571637077 encapsulation mpls
   mtu 9202
 !