# rtoa-pgatram-mce.pl
# Example run: perl rtoa-pgatram-mce.pl t1.txt >mce.tmp
#
# Convert a "modern" Roman Numeral to its arabic (decimal) equivalent.
# The alpabetic input string may be assumed to always contain a valid 
+Roman Numeral in the range 1-3999.
# Roman numerals may be upper or lower case.
# Error handling is not required.
# For example:
#    input "XLII" should produce the arabic (decimal) value 42
#    input "mi"   should produce the arabic (decimal) value 1001

use strict;
use warnings;
use Time::HiRes qw(time);
use MCE;

# Function roman_to_arabic
# Output a list of their arabic (decimal) values to standard output.
#
sub roman_to_arabic {
   my $files = shift;    # in:  reference to a list of files containin
+g Roman Numerals (one per line)
   my $apply_cpu_affinity = ( $^O =~ /linux/i ) ? 1 : 0;
   my @rtoa;
   @rtoa[unpack 'c*', 'MDCLXVImdclxvi'] = (qw( 1000 500 100 50 10 5 1 
+)) x 2;

   # construct a pool of workers
   my $mce = MCE->new(
      max_workers => MCE::Util::get_ncpu(),
      chunk_size  => 90 * 1024,
      init_relay  => 1,   # if defined, tells MCE to load MCE::Relay p
+lus extra setup
      posix_exit  => 1,
      use_slurpio => 1,
      user_begin  => sub {
         if ( $apply_cpu_affinity ) {
            my $cpu = (MCE->wid - 1) % MCE::Util::get_ncpu();
            system("taskset -cp $cpu $$ >/dev/null");
            $apply_cpu_affinity = 0;
         }
      },
      user_func   => sub {
         my ( $mce, $slurp_ref, $chunk_id, $output ) = ( @_, '' );
         open my $fh, '<', $slurp_ref;
         while ( <$fh> ) {
            chomp;
            my $n = 0;
            $n += $_ - $n % $_ * 2 for @rtoa[ unpack 'c*', $_ ];
            $output .= "$n\n";
         }
         close $fh;
         # output orderly
         MCE::relay {
            print $output;
         };
      }
   );

   # process a list of files
   for my $fname ( @{$files} ) {
      warn("$0: cannot access '$fname': No such file or directory\n"),
+ next
         unless -e $fname;
      warn("$0: cannot access '$fname': Permission denied\n"), next
         unless -r $fname;
      warn("$0: cannot process '$fname': Is a directory\n"), next
         if -d $fname;
      $mce->process({ input_data => $fname });
   }

   # reap MCE workers
   $mce->shutdown;
}

@ARGV or die "usage: $0 file...\n";
my @rtoa_files = @ARGV;

warn "rtoa pgatram start\n";
my $tstart = time;
roman_to_arabic(\@rtoa_files);
warn sprintf("time %0.03f secs\n", time - $tstart);
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