#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11147096
use warnings;

sub expr
  {
  my $val = [];
  $val =
    /\G\s+/gc ? $val :
    /\G([^{}\s]+)/gc ? do { my $key = $1; [ @$val, /\G \{/gc
      ? { $key => (expr(), /\G\}/gc || die ' missing } ')[0] }
      : /\G "(.*?)"/gc ? { $key => $1 } : $key ] } :
    return ref $val eq 'ARRAY' && ( @$val == grep ref $_ eq 'HASH', @$val )
      ? { map %$_, @$val }
      : $val while 1
  }

sub parse
  {
  local $_ = join '', @_;
  my $parse = expr;
  pos($_) == length $_ or die "incomplete parse stopped at ", substr $_, pos($_);
  return $parse;
  }

my $parse = parse( <DATA> );
$Data::Dump::LINEWIDTH = 26;
use Data::Dump 'dd'; dd $parse;

__DATA__
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 }
        }
    }
}