#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

use Marpa::R2;
use Data::Dumper;

my $input = q(sys ecm cloud-provider /Common/aws-ec2 {
    description "The aws-ec2 parameters"
    property-template {
        account { }
        availability-zone {
            valid-values { a b c d }
        }
        instance-type {
            valid-values { t2.micro t2.small t2.medium }
        }
        region {
            valid-values { us-east-1 us-west-1 }
        }
    }
});

my $dsl = << '__DSL__';

lexeme default = latm => 1

:default ::=                       action => first
Top      ::= atom Attrs Struct     action => top
Attrs    ::= atom Attrs            action => merge
           | atom                  action => newlist
Struct   ::= ('{') Elements ('}')
Elements ::= Element Elements      action => merges
           | Element
Element  ::= atom Value            action => struct
           | atom Struct           action => struct
Value    ::= Struct
           | ('"') string ('"')
           | ('{ }')               action => empty
          || ('{') List ('}')
List     ::= atom List             action => merge
           | atom                  action => newlist

:discard ~ [\s]
string ~ [^"]+
atom   ~ [^\s{}]+

__DSL__

sub top     { +{ $_[1] => { attrs => $_[2], contents => $_[3] } } }
sub first   { $_[1] }
sub empty   { [] }
sub newlist { [ $_[1] ] }
sub merge   { [ $_[1], @{ $_[2] } ] }
sub struct  { +{ $_[1] => $_[2] } }
sub merges  { +{ %{ $_[1] }, %{ $_[2] } } }


my $grammar = 'Marpa::R2::Scanless::G'->new({ source => \$dsl });
my $recce = 'Marpa::R2::Scanless::R'->new({ grammar           => $grammar,
                                            semantics_package => 'main',
                                          });
$recce->read(\$input);
use Data::Dumper; print Dumper($recce->value) =~ s/  / /gr;