use strict;
use warnings;
use Data::Dumper;

my $s = <<'END';
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 }
        }
    }
}
END

my %valid_keys = map { $_, 1 } qw/
    description
    property-template
    account
    availability-zone
    instance-type
    valid-values
    region
/;

$s =~ s/
(?|
    "([^"{}]+)"
    |
    (?:^|(?<=\s))
        ([^\s{}]+)
    (?:$|(?=\s))
)
/"$1"/xg;
$s =~ s/("|})\s\K/,/g;
$s =~ tr/{}/[]/;

print Dumper fix_aref([ eval $s ]);

sub fix_aref {
    my $aref = shift;
    
    ref and $_ = fix_aref($_) for @$aref;
    
    return $aref unless $#$aref % 2;
    
    for ( 0 .. $#$aref ) {
        next if $_ % 2;
        return $aref 
            unless exists $valid_keys{ ${$aref}[$_] }
    }
    return +{ @$aref }
}


##</code><code>##

$VAR1 = [
          'sys',
          'ecm',
          'cloud-provider',
          '/Common/aws-ec2',
          {
            'property-template' => {
                                     'region' => {
                                                   'valid-values' => [
                                                                       'us-east-1',
                                                                       'us-west-1'
                                                                     ]
                                                 },
                                     'availability-zone' => {
                                                              'valid-values' => [
                                                                                  'a',
                                                                                  'b',
                                                                                  'c',
                                                                                  'd'
                                                                                ]
                                                            },
                                     'instance-type' => {
                                                          'valid-values' => [
                                                                              't2.micro',
                                                                              't2.small',
                                                                              't2.medium'
                                                                            ]
                                                        },
                                     'account' => {}
                                   },
            'description' => 'The aws-ec2 parameters'
          }
        ];