hash as a poor man's switch

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

use Carp qw{ confess };
use List::Util qw{ shuffle };
use Test::More tests => 5;
use Benchmark qw{ cmpthese };

my @ATTRS;
my (
    $ORD, $ROOT, $PARENT, $FIRSTCHILD, $NEXTSIBLING, $MISC, # both root and node
    $FORM, $LEMMA, $UPOS, $XPOS, $FEATS, $DEPREL, $DEPS,    # node only
);

BEGIN {
    @ATTRS = qw(ord root parent firstchild nextsibling misc
                form lemma upos xpos feats deprel deps);
    ($ORD, $ROOT, $PARENT, $FIRSTCHILD, $NEXTSIBLING, $MISC) = (0..5);
    ($FORM, $LEMMA, $UPOS, $XPOS, $FEATS, $DEPREL, $DEPS)    = (6..12);
}

my $self = [ 0 .. 12 ];


sub ternary {
    my @values = map {
          $_ eq 'ord'    ? $self->[$ORD]
        : $_ eq 'form'   ? $self->[$FORM]
        : $_ eq 'lemma'  ? $self->[$LEMMA]
        : $_ eq 'upos'   ? $self->[$UPOS]
        : $_ eq 'xpos'   ? $self->[$XPOS]
        : $_ eq 'feats'  ? $self->[$FEATS]
        : $_ eq 'deprel' ? $self->[$DEPREL]
        : $_ eq 'deps'   ? $self->[$DEPS]
        : $_ eq 'misc'   ? $self->[$MISC]
        : confess "Unknown attribute '$_'";
    } @_;
}


{   my %h = ( ord    => $ORD,
              form   => $FORM,
              lemma  => $LEMMA,
              upos   => $UPOS,
              xpos   => $XPOS,
              feats  => $FEATS,
              deprel => $DEPREL,
              deps   => $DEPS,
              misc   => $MISC,
    );
    
    sub hash {
        map $h{$_} // confess("Unknown attribute '$_'"), @_
    }
}


my @values = shuffle qw( ord form lemma upos xpos feats deprel deps misc );

is_deeply [ ternary(@values) ], [ hash(@values) ], 'same values';

my $exception_regex = qr/^Unknown attribute 'x' at/;
isnt eval { ternary('x'); 1 }, 1, 'ternary dies';
like $@, $exception_regex, 'ternary exception';

isnt eval { hash('x'); 1 }, 1, 'hash dies';
like $@, $exception_regex, 'hash exception';


cmpthese( -5,
          { ternary => sub { ternary(@values) },
            hash    => sub { hash(@values)    },
          }
);