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

my @els = qw( Book Snap Line1 Line2 Line3 Line4 Line5 );

use XML::LibXML::Reader;
my $reader = XML::LibXML::Reader->new(location => 'file.xml')
    or die;

my (%line, $C);
while ($reader->read) {
    next unless $reader->nodeType == XML_READER_TYPE_ELEMENT;
    my $name = $reader->name;

    if (grep $_ eq $name, @els) {
        $line{$name} = $reader->copyCurrentNode(1)->textContent;

    } elsif ($name =~ /^C[123]$/) {
        $C = $name;

    } elsif ($name =~ /^[XY]$/) {
        push @{ $line{$C}{$name} }, $reader->copyCurrentNode(1)->textC
+ontent;

    } elsif ('Author' eq $name) {
        for my $c (qw( C1 C2 C3 )) {
            for my $letter (qw( X Y )) {
                print join '|', @line{@els}, "$c.$letter", @{ $line{$c
+}{$letter} };
                print "\n";
            }
        }
        %line = ();
    }
}
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