XML::Twig - extracting some tags from siblings

aakikce has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I need to grouping heading and its content. I got output by simple regex find and replace. But I need to do it using XML::Twig.

My input is

<root>
<ahead>first head</ahead>
<x>som text</x>
<s>some text</s>
<b>some text</b>
<k>some text</k>
<ahead>first head</ahead>
<s>some text</s>
<b>some text</b>
<k>some text</k>
<j>some text</j>
</root>
[download]

Output

<root>
<aheadtext>
<ahead>first head</ahead>
<x>som text</x>
<s>some text</s>
<b>some text</b>
<k>some text</k>
</aheadtext>
<aheadtext>
<ahead>second head</ahead>
<s>some text</s>
<b>some text</b>
<k>some text</k>
<j>some text</j>
</aheadtext>
</root>
[download]

I got the sibling nodes by following code

$t->parse($content);
@sib = $t->get_xpath('//ahead', 0)->next_siblings();
[download]

I got all siblings in @sib including second ahead and its data. How to add the condition in next_siblings() to get the first ahead contents only?

Thanks,

Aakikce

Comment on XML::Twig - extracting some tags from siblings Select or Download Code

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Re: XML::Twig - extracting some tags from siblings by mirod (Canon) on Jun 05, 2007 at 12:36 UTC
You can't do that with a simple condition. The simplest is probably to do something like (untested): `my @sheads= $t->root->children( 'shead'); foreach my $shead (@sheads) { my $aheadtext= $shead->wrap_in( 'aheadtext'); my $more_text= $aheadtext->next_sibling; while( $more_text->tag ne 'shead') { $more_text->move( last_child => $aheadtext); $more_text= $aheadtext->next_sibling; } }` [download]	[reply] [d/l]
Re^2: XML::Twig - extracting some tags from siblings by aakikce (Acolyte) on Jun 05, 2007 at 14:57 UTC
Hi Mirod, Thanks for your reply. what you have given is exactly correct. But I am struggling with the 'while' loop. I tested with the 'if' loop many times, it runs properly. In 'while' loop I get error as can't call method tag. `if ($more_text->tag ne "ahead") { $more_text->move(last_child => $aheadtext); $more_text = $aheadtext->next_sibling; } if ($more_text->tag ne "ahead") { $more_text->move(last_child => $aheadtext); $more_text = $aheadtext->next_sibling; }` [download] Can you please explain. thanks, AAkikce	[reply] [d/l]
Re^3: XML::Twig - extracting some tags from siblings by mirod (Canon) on Jun 05, 2007 at 15:34 UTC
I told you it was untested! ;--) Of course at some point you get to the last child, and `$aheadtext->next_sibling;` doesn't exist, so `$more_text` becomes `undef`. So the test should not be `while( $more_text->tag ne 'shead')`, which will die when you trying to call the `tag` method on the `undef` value in `$more_text`, but `while( $more_text && ($more_text->tag ne 'shead'))`. Does that help?	[reply] [d/l] [select]