#!/usr/bin/perl
use warnings;
use strict;

use Marpa::R2;

my $dsl = << '__DSL__';

lexeme default = latm => 1
:default ::= action => ::first

Config     ::= Assignment Config                       action => merge
             | Assignment                              action => creat
+e_config
Assignment ::= Var (space equals space) Value (space)  action => assig
+n
Value      ::= number
             | String
String     ::= (quote) Quoteds (quote)
Quoteds    ::= Quoted Quoteds                          action => conca
+t
             | Quoted
Quoted     ::= nonquote
             | quotedquote                             action => quote
Var        ::= Name
            || Array
Array      ::= atsign Name Index                       action => name_
+index
Name       ::= alpha alnum                             action => conca
+t
Index      ::= (leftsquare) number (rightsquare)

space       ~ [\s]*
alnum       ~ [\w]+
alpha       ~ [[:alpha:]]
atsign      ~ '@'
equals      ~ '='
leftsquare  ~ '['
nonquote    ~ [^']
number      ~ [\d]+
quotedquote ~ '\'[']
quote       ~ [']
rightsquare ~ ']'
__DSL__

sub concat { $_[1] . $_[2] }
sub name_index { [ $_[2], $_[3] ] }
sub quote { "'" }
sub assign { [ ref $_[1] ? @{ $_[1] } : $_[1], $_[2] ] }

sub merge {
    my %config = %{ $_[-1] };
    (2 == @{ $_[1] } ? $config{ $_[1][0] } : $config{ $_[1][0] }[ $_[1
+][1] ])
        //= $_[1][-1];
    return \%config
}

sub create_config {
    my %config;
    $config{ $_[1][0] }
        = @{ $_[1] } == 2 ? $_[1][1]
                          : do {
                              my $ar = [];
                              $ar->[ $_[1][1] ] = $_[1][2];
                              $ar
                          };
    \%config
}

my $grammar = 'Marpa::R2::Scanless::G'->new({source => \$dsl});

my $input = do { local $/; <DATA> };
my %config = %${ $grammar->parse(\$input, 'main') };

use Data::Dumper; print Dumper \%config

__DATA__
@arr[2] = 3
str = 'xyz'
@arr[2] = 5
str = 'abc\'d'
@arr[1] = '#+#:'
[download]

Output:

$VAR1 = {
          'str' => 'abc\'d',
          'arr' => [
                     undef,
                     '#+#:',
                     '5'
                   ]
        };
[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]