use Regexp::Common;
sub t2p {
    local $_ = $_[0];
    my $last = my $root = [];
    my @prev;
    pos($_)=0;
    while( length > pos ){
        if( m{ \G \s+ }gscx ){
            next; # ignore space
        } elsif( m{ \G \{ }gscx ){
            push @$last, my $new = [];
            push @prev, $last;
            $last = $new;
        } elsif( m{ \G \} }gscx ){
            $last = pop @prev;
#~         } elsif( m{ \G ( [^\s\{\}]+ ) }gscx ){
        } elsif( m{ \G ( $RE{quoted} ) }gscx ){
            push @$last, $1;
#~         } elsif( m{ \G ( [^\s\{\}]+ ) }gscx ){
        } elsif( m{ \G ( [^\{\}\\]+ | \\[\{\}] ) }gscx ){
            push @$last, $1;
        } elsif( m{ \G (.) }gscx ){
            push @$last, { error => $1 };
        }
    }
    $root
}