#!/usr/bin/perl
use strict;
use warnings;

{
  package Text::CSVPreserveQuotes;

  use base 'Text::CSV_XS';

  sub new
  {
    my ($class) = @_;

    my $self = $class->SUPER::new
    ({ quote_char     => undef,
       eol            => "\n",
       escape_char    => undef,
       sep_char       => ",",
     });
    bless $self, $class;
  }

  # my ($row, $quote) = $csv->getline($io);
  #
  # $quote is opaque; pass it to print()
  #
  sub getline
  {
    my ($self, $io) = @_;

    my $row = $self->SUPER::getline($io);
    return if not defined $row;
    my $quote = [];

    for (@$row)
    {
      push @$quote, s[^"(.*)"$][$1]s ? 1 : 0;
    }

    return ($row, $quote);
  }

  # $csv->print($io, $row, $quote);
  #
  # $quote is what you got from ->getline()
  #
  # $row and $quote will get mangled!
  #
  sub print
  {
    my ($self, $io, $row, $quote) = @_;

    for (@$row)
    {
      $_ = qq{"$_"} if shift @$quote;
    }

    $self->SUPER::print($io, $row);
  }
}

use IO::Wrap qw( wraphandle );
my $data = wraphandle(\*DATA);
my $stdout = wraphandle(\*STDOUT);

my $csv = Text::CSVPreserveQuotes->new();

while (1)
{
  my ($row, $quote) = $csv->getline($data);
  die if not defined $row;
  last if @$row == 0;

  # Munge
  #
  for (@$row)
  {
    if (/^[\d.]+$/) { $_ += 42 }
    else            { tr/A-Za-zm/N-ZA-Mn-za-m/ }
    $_ = "<$_>";
  }

  $csv->print($stdout, $row, $quote);
}

__DATA__
"hi",3,20.6,"green","32"
16,"alpha",0.00
"bye",3,27.6,"green","32"
16,"beta",0.00
"This won't work, since it has an embedded comma"
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