$ perl parser.pl
16/4*2
{
          '/' => [
                   '16',
                   {
                     '*' => [
                              '4',
                              '2'
                            ]
                   }
                 ]
        }

##</code><code>##

my $precedence=[qr/(?:&&|\|\|)/,qr/(?:\+|-)/,qr/(?:\/|\*)/];

##</code><code>##

{
          '*' => [
                   {
                     '/' => [
                              '16',
                              '4'
                            ]
                   },
                   '2'
                 ]
        }

##</code><code>##

my $precedence=[qr/(?:\/|\*)/,qr/(?:\+|-)/,qr/&&/,qr/|\|\|/];