Only xpath for extracting text for multiple conditions in xml - no code possible - xpath

Question

I have an example file with three conditions to be met... I also have no control over the xml file I get:
<?xml version="1.0" encoding="UTF-8"?>
<rootelement>
<Description>
<Note countries="AR,GB,US" >
<P countries="AR" >We want this one as it's AR.</P>
<P countries="US" >We don't want this one as it's not AR.</P>
<P countries="GB" >We don't want this either as it's not AR.</P>
</Note>
</Description>
<Description>
<Note countries="AR,GB,US" >
<P>Everyone in AR, GB and US gets to buy.</P>
<P>No restrictions for this product in these countries.</P>
</Note>
</Description>
<Description>
<Note>
<P>No country, that's because it will be treated as AR.</P>
</Note>
</Description>
</rootelement>
The task is threefold:
Extract text from <P> where countries="AR", other values are always ignored
Extract text from <P> where it's parent element (in this example but it's not always the case) contains AR in the countries attribute (countries="AR,GB,US" for example)
Extract text from current element (<P> in this example, not always) when there is no countries attribute present in the current element or it's ancestors
I hope that's clear, I tried to put three examples in the xml above and I need to extract these texts with my rule(s):
<P countries="AR" >We want this one as it's AR.</P>
<P>Everyone in AR, GB and US gets to buy.</P>
<P>No restrictions for this product in these countries.</P>
<P>No country, that's because it will be treated as AR.</P>
Ideally I want one rule. But I could use several as the rules are applied hierarchically.
If I use this in the application I'm feeding:
//*[contains(#countries,'AR')]/*
All good to get the first three, but I also get US and GB which I don't want. I can exclude them with this:
//*[contains(#countries,'AR')]/*[not(contains(#countries,'US')) and not(contains(#countries,'GB'))]
But the expression will become unmanageable in practice as there are many languages and I often need to change the ones I'm looking for. I cannot figure out how to say just exclude any that don't contain AR.
And then I still have the last problem of being able to extract if the countries attribute is missing altogether. This bit I'm at a complete loss to know how to resolve without affecting the previous results.

Answer 1

Here's an XPath 1 expression which I think captures the logic you've described:
//*[text()[normalize-space()]]
[
not(ancestor-or-self::*/#countries) or
contains(ancestor-or-self::*[#countries][1]/#countries, 'AR')
]
Any element which has a child text node which is not just white space, and
which has no countries attribute of its own or on any of its ancestor elements, or
has 'AR' either in its own countries attribute or the first countries attribute of any of its ancestors.
NB the ancestor-or-self axis is a 'reverse' axis which means the expression ancestor-or-self::* will return the context node itself, then its parent, then its grand-parent, etc, in that order, finishing at the root element of the document. The expression ancestor-or-self::*[#countries] will filter that list to include only the elements which have a countries attribute, and ancestor-or-self::*[#countries][1] will return the first element in that list. If the element that contains the text has a countries attribute, then it will be first in that list, otherwise the nearest ancestor will be first. I think this "inheritance" is what you're wanting to achieve?
Results:
<P countries="AR">We want this one as it's AR.</P>
<P>Everyone in AR, GB and US gets to buy.</P>
<P>No restrictions for this product in these countries.</P>
<P>No country, that's because it will be treated as AR.</P>