private static bool TryNonExclusiveQueryDeterministicParent(
out ELNode foundNode,
out ELNodeEnumerator enumerator,
ELNode parentNode,
object key,
LogicVariable v)
{
// Deterministic parent path
// The expression is UniqueParent/Something
if (parentNode.IsExclusive)
{
throw new ELNodeExclusionException("Non-exclusive query of an exclusive node", parentNode, key);
}
if (v == null)
{
// fully deterministic path
// UniqueParent/Key corresponds to at most one ELNode.
enumerator = null;
return parentNode.TryLookup(key, out foundNode);
}
// UniqueParent/Variable, so do a singly-nested iteration.
foundNode = null;
enumerator = new ELNodeEnumeratorLogicVariableFromNode(parentNode, v);
return true;
}
private static bool TryExclusiveQueryDeterministicParent(
out ELNode foundNode,
out ELNodeEnumerator enumerator,
ELNode parentNode,
object key,
LogicVariable v)
{
// Deterministic parent path
// UniqueParent:Something
if (parentNode.IsNonExclusive)
{
throw new ELNodeExclusionException("Exclusive query of an non-exclusive node", parentNode, key);
}
if (v == null)
{
// Deterministic child path
// UniqueParent:Key
enumerator = null;
return parentNode.TryLookup(key, out foundNode);
}
// Enumerated child path
// UniqueParent:Variable
if (parentNode.Children.Count > 0)
{
foundNode = null;
enumerator = new ELNodeEnumeratorBindAndUnbindVariable(parentNode.Children[0], v);
return true;
}
// parentNode is exclusive, but is childless, so we can't match.
foundNode = null;
enumerator = null;
return false;
}