XML parsing and Lists

[madbee]

Hello! I'm trying to parse an XML file, sample of which is below.

<Aritcle>
  <Main>
   <Sect>
     <H4>Include</H4>
      .....
      <P1> This is the criteria</P1>
      <L>
        <LI>
          <LI_Label>1.</LI_Label>
          <LI_Title>Critera 1</LI_Title>
         </LI>
         <LI>
          <LI_Label>2.</LI_Label>
          <LI_Title>Critera 2</LI_Title>
         </LI>
          <LI>
          <LI_Label>3.</LI_Label>
          <LI_Title>Critera 3</LI_Title>
         </LI>
          <LI>
          <LI_Label>4.</LI_Label>
          <LI_Title>Critera 3</LI_Title>
         </LI>
        </Sect>
     </Main>
   </Article>

I am using: XML::LibXML for parsing this. I can easily get the entire section of lists. However, my problem is I just need to know how many LIST elements are there. One way I was thinking is:

1. Parse the xml for the sec4. store contents in array

2. Loop through array until I get the first LIST element. Track counter;

3. Increment counter for each LIST element found until the last LIST element is reached.

While this approach may work, I feel this is very kludgy. So I am looking to see if there is an elegant way I can count the number of list elements in a section

The challenge ofcourse is that not every XML file I am parsing has the exact same structure. There could be variations where the <P1> This is the criteria</P1> may not exist before the start of the list.

Hoping someone here has some thoughts on how best I can capture the count of list elements

Sadly, I cannot use XPath here since I have an entire piece of code built around LibXML parsing. Also I'm having an Xpath installation nightmare which I just cannot get past.

Thanks so much in advance.

Regards,Madbee

[choroba]

Using XML::LibXML without XPath (that is, XML::LibXML::XPathContext is like driving a Jaguar without tyres. Just compare your description to the succinctness of

count(Sect[4]//LI)

[madbee]

Thanks for responding.I was not aware of XPathContext module in LibXML. I was trying to use XML::XPath directly and got into an infinite loop of installation issues which I could not get past.

I will try using this approach. Basically, I have to create a array of nodes for the path:

    $parser = XML::LibXML->new;    
    $dom = $parser->parse_file($file);
    
    $root = $dom->getDocumentElement;
    $dom->setDocumentElement($root);
    

    my $xc = XML::LibXML::XPathContext->new($file);
    my @nodes=$xc->findnodes('//Article//Part//Sect//H5[ contains(.,"I
+nclude")]',$dom);



if (@nodes)
{
$count = $xc->findvalue('count(//Article//Part//Sect//LI)',$dom);
    print $count;
}

Am I on the right track? Anything I'm missing?

Thanks much.

[choroba]

You are overcomplicating the problem. Do not use setDocumentElement, it creates a new root element. The constructor of XPathContext takes a context node as a parameter, not a file. This is a Short, Self Contained, Correct Example:

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

use XML::LibXML;

my $dom = XML::LibXML->load_xml(string => << '__XML__');
<Article> <!-- fixed typo -->
  <Main>
   <Sect>
     <H4>Include</H4>
      .....
      <P1> This is the criteria</P1>
      <L>
        <LI>
          <LI_Label>1.</LI_Label>
          <LI_Title>Critera 1</LI_Title>
         </LI>
         <LI>
          <LI_Label>2.</LI_Label>
          <LI_Title>Critera 2</LI_Title>
         </LI>
          <LI>
          <LI_Label>3.</LI_Label>
          <LI_Title>Critera 3</LI_Title>
         </LI>
          <LI>
          <LI_Label>4.</LI_Label>
          <LI_Title>Critera 3</LI_Title>
         </LI>
        </L> <!-- fixed missing closing tag -->
        </Sect>
     </Main>
   </Article>
__XML__

my $xc = XML::LibXML::XPathContext->new;

my $count = $xc->findvalue('count(//Article//Sect//LI)', $dom);
print "$count list nodes found.\n" if $count;