#!/usr/bin/perl
use strict;

open my $fh, $ARGV[0] or die "Couldn't open '$ARGV[0]': $!";

my $iter = records( blocks($fh), qr/\s*,\s*/ );

while ( defined(my $rec = $iter->()) ) {
    print $rec, "----\n";
}

sub blocks {
    my $fh = shift;
    my $blocksize = shift || 8192;
    sub {
        return unless read $fh, my($block), $blocksize;
        return $block;
    }
}

sub records {
    my $blocks = shift;
    my $terminator = @_ ? shift : quotemeta($/);
    my @records;
    my ($buf, $finished) = ("");
    sub {
        while (@records == 0 && ! $finished) {
            if (defined(my $block = $blocks->())) {
                $buf .= $block;
                my @newrecs = split /($terminator)/, $buf;
                while (@newrecs > 2) {
                    push @records, shift(@newrecs).shift(@newrecs);
                }
                $buf = join "", @newrecs;
            } else {
                @records = $buf;
                $finished = 1;
            }
        }
        return shift(@records);
    }
}