#!/usr/bin/perl -wnl
use strict;
print;
print join ' / ', map qq["$_"], m[\G (
        ' (?: \\ . | '' | [^'] ) + '
        |
        " (?: \\ . | "" | [^"] ) + "
        |
        (?: \\ . | [^'"] ) + 
) ]gx;
print "";

##</code><code>##

sub make_dequote_rx {
    my @char = map quotemeta, @_;
    my $chars = join '', @char;
    my $rx = join(
        ' | ',
        map(qq[$_ (?: \\\\ . | $_$_ | [^$_] ) + $_], @char),
        qq[(?: \\\\ . | [^$chars] ) +],
    );
    return qr/\G ( $rx )/x;
}

my $dequote = make_dequote_rx qw(' ");