use strict;
use warnings;

use Data::Dumper;

sub filter_and_return_ref {
    my $in = shift;

    my @lines = split /\n/, $in;
    for ( @lines ) {
        s{ \A (\S+) }{$1 =>}xms;
        $_ .= ',';
    }
    unshift @lines, '{';
    push @lines, '}';

    return eval join q{}, @lines;
}

my $unfiltered = <<'END_OF_UNFILTERED';
key1 "value1"
key2 "value2"
key3 "value3"
END_OF_UNFILTERED
    ;

my $data_ref = filter_and_return_ref( $unfiltered );
print Dumper $data_ref;
__END__
$VAR1 = {
          'key2' => 'value2',
          'key1' => 'value1',
          'key3' => 'value3'
};