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In XPath 1.0, how can I select all descendant nodes C of current (context) node A, that are not contained in an intervening node of type B?

For example, find all <a> links contained in the current element, that are not inside a <p>. But if the current element is itself inside a <p>, that's irrelevant.

<p>                   <—— this is irrelevant, because it's outside the current element
    ...
    <div>             <—— current element (context node)
        ...
        <a></a>       <—— the xpath should select this node
        ...
        <p>
            ...
            <a></a>   <—— but not this, because it's inside a p, which is inside context
            ...
        <p>
        ...
    </div>
    ...
</p>

The ... in the example could be several depths of intervening nodes.

I'm writing XSLT 1.0, so the additional functions generate-id(), current(), and such are available.

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  • Something like /p/div/a ? And this is duplicate of stackoverflow.com/questions/15818191/… Commented Aug 28, 2015 at 13:37
  • 1
    @fukanchik no, I'm already in the div (current context node) and I need to select all a that are not inside a p, possibly with several middle nodes in between, for example several levels of div in between. Commented Aug 28, 2015 at 13:38

1 Answer 1

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This is one possible XPath :

.//a[not(ancestor::p/ancestor::* = current())]

This XPath checks if current descendant a element doesn't have ancestor p which ancestor is current context node. In other words, it checks if the a element doesn't have ancestor p intervening between the a and the current context node.

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5 Comments

That makes sense, but is the = doing the right thing there? Don't I need something like .//a[not(ancestor::p/ancestor::*[generate-id(.) = generate-id(current())])] ?
@Tobia Sorry, I'm not sure my self if the expression will compare the element's value or compare the elements by reference (which I hope it to do)
I don't think it's right, because "If both objects to be compared are node-sets, then the comparison will be true if and only if there is a node in the first node-set and a node in the second node-set such that the result of performing the comparison on the string-values of the two nodes is true." source
Still, either your expression or my generate-id() variant will do. Thanks!
why start with .// rather than // ?

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