#!/usr/bin/perl --
use XML::Twig;
BEGIN { *XML::Twig::Elt::x = *XML::Twig::Elt::get_xpath; }

use strict;
use warnings;

my $str = <<'EOF';
<fudge>
  <factory>
    <drop>
      <bindname>qqqqq</bindname>
      <bindpass>welcome</bindpass>
    </drop>
    <drop>
      <bindname>abcde</bindname>
      <bindpass>welcome</bindpass>
    </drop>
  </factory>
</fudge>
EOF

{
    my $t = XML::Twig->new(
        pretty_print  => 'indented',
        twig_handlers => {
            
            '//factory/drop' => sub {
                if ( not $_->x('bindname[string()=~/abcde/]') ) {
                    if ( my ($pass) = $_->x('bindpass[string()="welcome"]') ) {
                        $pass->set_text( uc $pass->text );
                    }
                }
            },
        },
    );
    $t->parse($str);
    $t->print();
}

{
    my $bozo = 0;
    my $t    = XML::Twig->new(
        pretty_print  => 'indented',
        twig_handlers => {

            '//factory/drop/bindname' => sub {
                $bozo = 1 if $_->text =~ /abcde/;
            },
            '//factory/drop/bindpass' => sub {
                if ( not $bozo and $_->text =~ /welcome/ ) {
                    $_->set_text( uc $_->text );
                }
                $bozo = 0;
            },
        },
    );
    $t->parse($str);
    $t->print();
}

__END__