Perl反序列化XML

Question

我有XML文件（某些应用程序的输出），如下所示：

<data>
    <call function="get_user_data">
        <output>
            <integer name="my_id" value="-31" />
            <string name="login" value="root" />
            <integer name="ip_list" value="2" />
            <array name="i">
                <item>
                    <ip_address name="user_ip" value="0.0.0.0" />
                    <ip_address name="user_mask" value="0.0.0.0"/>
                </item>
                <item>
                    <ip_address name="user_ip" value="94.230.160.230" />
                    <ip_address name="user_mask" value="255.255.255.0"/>
                </item>
            </array>
            <integer name="modules" value="2" />
            <array name="i">
                <item>
                    <string name="module_name" value="core" />
                </item>
                <item>
                    <string name="module_name" value="devices" />
                </item>
            </array>
            <integer name="addition_modules" value="0"/>
            <array name="i"/>
        </output>
    </call>
</data>

我需要为这个perl结构解析它：

$data = {
    my_id => -31,
    login => "root",
    ip_list => [
        {
            user_ip => "0.0.0.0",
            user_mask => "0.0.0.0"
        },
        {
            user_ip => "94.230.160.230",
            user_mask => "255.255.255.0"
        }
    ],
    modules => [
        {
            module_name => "core"
        },
        {
            module_name => "devices"
        }
    ],
    addition_modules => []
}

帮帮我，PLZ，去做吧！

Answer 1

这是一种糟糕的XML格式。这是多余的：为什么给出每个数组的元素数量，它就在那里，并且层次结构没有很好地定义：数组的名称（如果你必须拥有它，它的元素数量）应该是数组的属性，而不是它在同一级别之前的元素。

无论如何......你的格式是如此具体，我怀疑你可以在这里使用通常的XML :: Simple，所以我拿出了XML :: Twig，我认为这样做：

#!/usr/bin/perl 

use strict;
use warnings;

use XML::Twig;
use Test::More tests => 1;

my $expected= {
    my_id => -31,
    login => "root",
    ip_list => [
        { user_ip => "0.0.0.0",
          user_mask => "0.0.0.0"
        },
        { user_ip => "94.230.160.230",
          user_mask => "255.255.255.0"
        }
    ],
    modules => [
        { module_name => "core" },
        { module_name => "devices" }
    ],
    addition_modules => []
};

my $data={};

my $t=XML::Twig->new( twig_handlers => { 'integer[@name="my_id"]' => sub { add_field( $data, $_)},
                                         'string[@name="login"]' => sub { add_field( $data, $_)},
                                         array => sub { array( $data, @_); },
                                       },
              )
         ->parse( \*DATA); # replace with parsefile( 'file.xml') to parse a file

is_deeply( $data, $expected, 'one test to rule them all');


sub array
  { my( $data, $t, $array)= @_;
    my $name= $array->prev_sibling( 'integer')->att( 'name');
    $data->{$name}=[];
    foreach my $item ($array->children( 'item'))
      { my $item_data={};
        foreach my $child ($item->children)
          { add_field( $item_data, $child); }
        push @{$data->{$name}}, $item_data;
      }
  }


# get a name/value pair of attributes and add it to a hash, which
# could be the overall $data or an element in an array
sub add_field
  { my( $data, $elt)= @_;
    $data->{$elt->att( 'name')}= $elt->att( 'value');
  }



__DATA__
<data>
    <call function="get_user_data">
        <output>
            <integer name="my_id" value="-31" />
            <string name="login" value="root" />
            <integer name="ip_list" value="2" />
            <array name="i">
                <item>
                    <ip_address name="user_ip" value="0.0.0.0" />
                    <ip_address name="user_mask" value="0.0.0.0"/>
                </item>
                <item>
                    <ip_address name="user_ip" value="94.230.160.230" />
                    <ip_address name="user_mask" value="255.255.255.0"/>
                </item>
            </array>
            <integer name="modules" value="2" />
            <array name="i">
                <item>
                    <string name="module_name" value="core" />
                </item>
                <item>
                    <string name="module_name" value="devices" />
                </item>
            </array>
            <integer name="addition_modules" value="0"/>
            <array name="i"/>
        </output>
    </call>
</data>