new.pl

use strict;
use warnings;
use Time::HiRes qw/gettimeofday tv_interval/;
use List::Util qw/sum0/;

use constant {
    ADD       => 0,
    SUBSTRACT => 1,
    MULTIPLY  => 2,
    DEVIDE    => 3,
    SUM       => 4
};

sub evaluate_ast {
    my $ast = shift;

    my ($oper, @args) = @$ast;

    my @evaluated_args = map { ref eq 'ARRAY' ? evaluate_ast($_) : $_ } @args;

    if ( $oper == ADD ) {
        return $evaluated_args[0] + $evaluated_args[1];
    }
    elsif ( $oper == SUBSTRACT ) {
        return $evaluated_args[0] - $evaluated_args[1];
    }
    elsif ( $oper == MULTIPLY ) {
        return $evaluated_args[0] * $evaluated_args[1];
    }
    elsif ( $oper == DEVIDE ) {
        return $evaluated_args[0] / $evaluated_args[1];
    }
    elsif ( $oper == SUM ) {
        return sum0(@evaluated_args);
    }
}

sub time_ast {
    my $ast = shift;
    my $t0 = [gettimeofday];

    my $iterations = 100_000;
    my $sum = 0;

    for (1..$iterations) {
        $sum += evaluate_ast($ast);
    }

    my $compute_time = tv_interval($t0);

    print "COMPUTED [$iterations] ITERATIONS IN [$compute_time] SECONDS\n";

    die "WRONG SUM $sum" if abs( $sum - 3900000) > 0.001; # ensure that code was executed
}

my $ast = [SUM,
    [ SUBSTRACT,[ADD,[DEVIDE,[MULTIPLY,10,20],30],40],50],
    [ SUBSTRACT,[ADD,[DEVIDE,[MULTIPLY,20,30],40],50],60],
    [ SUBSTRACT,[ADD,[DEVIDE,[MULTIPLY,30,40],50],60],70],
    [ SUBSTRACT,[ADD,[DEVIDE,[MULTIPLY,40,50],60],70],80]
];

time_ast($ast);