列出document元素的所有子节点

Question

我有一个非常庞大的XML文件,我想列出文档元素的所有子节点.我正在使用下面的代码工作正常,但它需要很长时间来处理文件,它也从文档元素获取数据,这是不需要的:

use XML::Simple;
my $xml = XML::Simple->new();
my $d = $xml->XMLin("sample.xml");
my @arr = keys %$d;
print "@arr\n";

示例XML:

    <?xml version="1.0" encoding="ISO-8859-15"?>
<document version="1.0" createdAt="2017-03-31T11:41:34">
   <TITLE>Computer Parts</TITLE>
   <PART001>
      <ITEM>Motherboard</ITEM>
      <MANUFACTURER>ASUS</MANUFACTURER>
      <MODEL>P3B-F</MODEL>
      <COST> 123.00</COST>
   </PART001>
   <PART002>
      <ITEM>Video Card</ITEM>
      <MANUFACTURER>ATI</MANUFACTURER>
      <MODEL>All-in-Wonder Pro</MODEL>
      <COST> 160.00</COST>
   </PART002>
   <PART003>
      <ITEM>Sound Card</ITEM>
      <MANUFACTURER>Creative Labs</MANUFACTURER>
      <MODEL>Sound Blaster Live</MODEL>
      <COST> 80.00</COST>
   </PART003>
   <PART004>
      <ITEM>14 inch Monitor</ITEM>
      <MANUFACTURER>LG Electronics</MANUFACTURER>
      <MODEL> 995E</MODEL>
      <COST> 290.00</COST>
   </PART004>
</document>

预期产出:TITLE,PART001,PART002,PART003,PART004

任何人都可以建议更快更好的方法来获得所需的输出？

Answer 1

通过使用XML :: LibXML和XPath.

use 5.014;
use warnings;
use XML::LibXML;

my $file = 'xml';
my $dom = XML::LibXML->load_xml(location => $file);

for my $child ($dom->findnodes( q{//document/*} )) {
    say $child->nodeName();
}

产量

TITLE
PART001
PART002
PART003
PART004

或者只是针对这种情况,如果你只需要PARTs

for my $part ($dom->findnodes( q{//*[contains(name(),'PART')]} )) {
    say $part->nodeName();
}

产量

PART001
PART002
PART003
PART004

编辑:使用拉解析器(不会将整个xml加载到内存中):

use 5.014;
use warnings;
use XML::LibXML::Reader qw(XML_READER_TYPE_ELEMENT);

my $file="xml";    
my $reader = XML::LibXML::Reader->new(location => $file) or die "problem $!";

while($reader->read()) {
        if( $reader->depth == 1 && $reader->nodeType == XML_READER_TYPE_ELEMENT ) {
                say $reader->name;
        }
}

TITLE
PART001
PART002
PART003
PART004

EDIT2

use 5.014;
use warnings;

use XML::LibXML::Reader qw(XML_READER_TYPE_ELEMENT);
my $file="xml";

my $reader = XML::LibXML::Reader->new(location => $file) or die "problem $!";
my $indoc;
while($reader->read()) {
        # sets the flag in youre inside the <document>
        if( $reader->name eq 'document' ) {
                $indoc = $reader->nodeType == XML_READER_TYPE_ELEMENT ? 1 : 0;
        }
        # all nodes with level 1 if they're inside of the <document>
        if( $indoc &&  $reader->depth == 1 && $reader->nodeType == XML_READER_TYPE_ELEMENT ) {
                say $reader->name;
        }
}

Answer 2

您可以XML::Twig根据其文档使用哪个是用于在树模式下处理大型XML文档的perl模块.

以下是适合您的用例的示例:

use feature qw(say);
use XML::Twig;

XML::Twig->new(twig_handlers => {
    'document/*' => sub {
        say $_->name; # print out the element name
        $_->purge; # remove the entire element from memory
    }   
})->parsefile('sample.xml');

与样本文档一起使用时,会打印出:

TITLE
PART001
PART002
PART003
PART004

使用流式解析器可能会更快.