#!/usr/bin/perl -w

use strict;
use Benchmark qw( cmpthese );

sub blockold {
    my $fh;
    open $fh, 'vsfull.csv';
    #binmode $fh;
    my @lines;
    my $block;
    my $left= '';
    while(  read $fh, $block, 8192  ) {
        $block = $left . $block;
        my $i = index $block, "\n";
        while($i > 0){
            push @lines, substr($block,0,$i);
            substr $block, 0, $i+1, '';
            $i = index $block, "\n";
        }
        $left = $block;
    }
    return @lines;
}

sub blockfix {
    my $fh;
    open $fh, 'vsfull.csv';
    my @lines;
    my $block;
    my $left= '';
    while(  read $fh, $block, 8192  ) {
        $block = $left . $block;
        my $i = index $block, "\n";
        while(  $i >= 0  ) {
            push @lines, substr($block,0,$i+1);
            substr $block, 0, $i+1, '';
            $i = index $block, "\n";
        }
        $left = $block;
    }
    return @lines;
}

sub blocknew {
    my $fh;
    open $fh, 'vsfull.csv';
    my @lines;
    my $block= '';
    while( read $fh, $block, 8192, length $block  ) {
        my $i;
        my $j= 0;
        while(  $i= 1 + index $block, "\n", $j  ) {
            push @lines, substr $block, $j, $i-$j;
            $j= $i;
        }
        substr( $block, 0, $j )= '';
    }
    return @lines;
}

sub splitnew {
    my $fh;
    open $fh, 'vsfull.csv';
    my @lines;
    my $block= '';
    while( read $fh, $block, 8192, length $block  ) {
        push @lines, split /(?<=\n)/, $block, -1;
        $block= pop @lines;
    }
    push @lines, $block   if  length $block;
    return @lines;
}

sub lineold {
    my $fh;
    my @lines;
    open $fh, 'vsfull.csv';
    while(<$fh>){
        push @lines, $_;
    }
    return @lines;
}

sub linenew {
    my $fh;
    my @lines;
    open $fh, 'vsfull.csv';
    @lines= <$fh>;
    return @lines;
}

my @bo= blockold();
my @bf= blockfix();
my @bn= blocknew();
my @lo= lineold();
my @ln= linenew();
my @sn= splitnew();
warn "blockold is broken!\n"   if  "@bo" ne "@ln";
warn "blockfix is broken!\n"   if  "@bf" ne "@ln";
warn "blocknew is broken!\n"   if  "@bn" ne "@ln";
warn "lineold is broken!\n"    if  "@lo" ne "@ln";
warn "splitnew is broken!\n"   if  "@sn" ne "@ln";

cmpthese( -3, {
    lo => \&lineold,
    ln => \&linenew,
    bo => \&blockold,
    bn => \&blocknew,
    bf => \&blockfix,
    sn => \&splitnew,
});