[relax-ng-comment] Validation of a document during contruction

[Peter Wilson <PWILSON@GORGE.NET>]

Rick thank you for  your reply.

It was not the general approaches that I was asking about but rather the
ways in which the machinery of Relax NG patterns could be leveraged (and
the tools required to think about this problem). It seems to me that the
general approaches fall back what you would do if you were using DTDs.

For instance if you have an element A with children [X,Y,Z] (using []
for child nesting),
and a partially constructed document: A[Y].
Then if you can construct the patterns for *1 and *2 in A[*1,Y,*2] you
can then check possible insertions at points 1 and 2 by checking the
nullability of the derivatives of *1 and *2.
In general there will be sets of  *1..n matches for more complicated
patterns.

I have found an interesting paper at
http://www.cs.berkeley.edu/~maratb/cs264/paper/node5.html
which addresses this issue of performing tree matches with wildcard
subtrees.