searching children of ancestors

mphare · October 8th, 2008, 12:27 PM

This may take a minute to explain, so please be patient.

I am using Saxon 9 on Windows.

I have a source document a simple structure such as:

a - b - x - y
      + c - d - e
      + c - d - e
      + c - d - e
  + b - x - y
      + c - d - e
      + c - d - e
      + c - d - e
  + b - x - y
      + c - d - e
      + c - d - e
      + c - d - e

My structure is really much deeper, but this will do to explain my problem.

I find myself at a 'y' node and I decide I need information from all the 'e' nodes that are descendants of my current 'b' node. I don't care about the 'e' nodes that are descendants of the other 'b' nodes.

My initial thought was to use: ancestor::node()//e to get the information. Problem is, and it is now obvious to me, I am getting all the 'e' nodes in the document, not just the ones that are descendants of my 'b' node.

What I need is a way to stop the ancestor once it has a hit on a descendant 'e' node, then reuse that ancestor to find all the 'e' nodes I am interested in.

Or I need another solution.

------------------------
Keep Moving Forward

GnuPG Key fingerprint = 1AD4 726D E359 A31D 05BF ACE5 CA93 7AD5 D8E3 A876

Michael Hare

samjudson · October 8th, 2008, 12:55 PM

There are many different ways of doing this depending out how fixed your structure is. But simply doing this should work:

ancestor::b//e

obviously if you know what b is two levels up from y, and e is two levels down, then something like the following would be much faster:

../../b/c/d/e

or perhaps if you don't know what c and d will be then the following:

../../b/*/*/e

/- Sam Judson : Wrox Technical Editor -/

mphare · October 8th, 2008, 01:09 PM

Yes, that is a possibility. What I had tried was to be more generic than needing to know the depth of the 'y' and the static relative position from it to the 'e' nodes.

Now, ancestor::b//e seems interesting. Maybe I was not using the ancestor construct correctly.
I will try that and see if it works.

Thanks!

------------------------
Keep Moving Forward

GnuPG Key fingerprint = 1AD4 726D E359 A31D 05BF ACE5 CA93 7AD5 D8E3 A876

Michael Hare