#!/usr/bin/perl -w
use strict;
use List::Util qw( reduce );

# Definition Syntax: <verb> <operation>;   <operation> can be SIMPLE, as in "+"
#   COMPLEX ops are defined by arrayref, and contain an array of <terms>.
#   <complex-op> = [<simple-op>,<pre-code>,<post-code>,<last-code>]  (all ,<*-code> is optional)
#   <*-code> can use pre-defined vars: ($a,$b)=@_[0,1];  $count=scalar @_; $result=result


my %ops = ( qw|add + subtract - multiply * divide / power ** |,
	         qw|greater > lesser < |,
	             #OP  ,Pre,Post,LAST
    xor      => ["&&",'$a=~$a'],
    all      => ["&&",'', '1 : 0'], 
    none     => ["||",'', '1 : 0', '!$result'], 
    any      => ["||",'', '1 : 0'],
    min      => ["<",'', '$a: $b'],
    max      => [">",'', '$a: $b'],
    mean     => ["+",'','','$result /=$count'],
    geomean  => ["*",'','','$result ** (1/$count)' ], 
    equal    => ["-",'','0:$b', '$result &&=1'], 
);

sub op_JIT_compile{
   my $op = shift;
   return if ref $ops{$op} eq 'CODE'; # Optimize for "Already compiled"
   my $opval = $ops{$op};
   # Complex case first - Handle "pre,post" op requirements.
   if (ref $opval eq 'ARRAY'){ # Allow for "pre", "post", and "last" operatons 
	 	##  Avoid "undef",s by passing in extra "?'s at end.      
      my ($realop,$pre,$post,$last) = (@$opval,('') x 4); 
      my $post_ternary = $post eq '' ? '' : qq|?$post|; 
      my $eval_this_sub = q|sub { ($a,$b) = my @F=@_; my $count=scalar @F;| . 
      							    q|;my $result= reduce {|
      							    			. $pre . 
       							    			q|; $a | 
      							    			.  $realop  .
      							    			q| $b| 
      							    			. $post_ternary . 
      							    			q| } @F ;|
      							      . $last .
      							    q| }|;
      #print qq[$op = $eval_this_sub\n\tOPS(realop,pre,post,last;)=$realop,$pre,$post,$last;\n];						    
	   $ops{$op} = eval $eval_this_sub;
   	return;
   }
   # This is the "simple" operator case ..
	$ops{$op} = eval q| sub { reduce { $a | .  $opval  . q| $b } @_ }|;
}
 

my $op = lc shift or die "You must specify an operation followed by numbers.\n";
die "Non-numeric input. $_\n" if grep /\[^-]?\D/, @ARGV;
die "Invalid operation ($op).\n" unless exists $ops{$op};
op_JIT_compile($op);
print "$op (@ARGV)= ". $ops{$op}->(@ARGV) . "\n";