/// <returns> The value represented by this xpath. Can only be evaluated when this xpath represents exactly one
/// reference, or when it represents 0 references after a filtering operation (a reference which _could_ have
/// existed, but didn't, rather than a reference which could not represent a real node).
/// </returns>
public override System.Object unpack()
{
lock (evaluated)
{
if (evaluated)
{
return(base.unpack());
}
//this element is the important one. For Basic nodeset evaluations (referring to one node with no
//multiplicites) we should be able to do this without doing the expansion
//first, see if this treeref is usable without expansion
int size = unExpandedRef.size();
bool safe = true;;
for (int i = 0; i < size; ++i)
{
//We can't evaluated any predicates for sure
if (unExpandedRef.getPredicate(i) != null)
{
safe = false;
break;
}
int mult = unExpandedRef.getMultiplicity(i);
if (!(mult >= 0 || mult == TreeReference.INDEX_UNBOUND))
{
safe = false;
break;
}
}
if (!safe)
{
performEvaluation();
return(base.unpack());
}
//TOOD: Evaluate error fallbacks, here. I don't know whether this handles the 0 case
//the same way, although invalid multiplicities should be fine.
try
{
//TODO: This doesn't handle templated nodes (repeats which may exist in the future)
//figure out if we can roll that in easily. For now the catch handles it
return(XPathPathExpr.getRefValue(instance, ec, unExpandedRef));
}
catch (XPathException xpe)
{
//This isn't really a best effort attempt, so if we can, see if evaluating cleany works.
performEvaluation();
return(base.unpack());
}
}
}
private void InitBlock()
{
TreeReference ref_Renamed = this.getReference();
//Either concretely the sentinal, or "."
if (ref_Renamed.Equals(sentinal) || (ref_Renamed.RefLevel == 0))
{
return(sentinal);
}
else
{
//It's very, very hard to figure out how to pivot predicates. For now, just skip it
for (int i = 0; i < ref_Renamed.size(); ++i)
{
if (ref_Renamed.getPredicate(i) != null && ref_Renamed.getPredicate(i).size() > 0)
{
throw new UnpivotableExpressionException("Can't pivot filtered treereferences. Ref: " + ref_Renamed.toString(true) + " has predicates.");
}
}
return(this.eval(model, evalContext));
}
}