private Node RenderFold(
Node n,
IEnumerable <Node> folds,
Stack <Configuration> configStack)
{
if (n.NodeKind == NodeKind.Config)
{
return(n);
}
Configuration conf;
if (n.TryGetConfiguration(out conf))
{
Contract.Assert(configStack.Count > 0 && configStack.Peek() == conf);
configStack.Pop();
}
if (folds.IsEmpty <Node>())
{
return(n);
}
else if (n.NodeKind == NodeKind.FuncTerm)
{
var rendered = folds.First <Node>() as Cnst;
Contract.Assert(rendered != null && rendered.CnstKind == CnstKind.String);
ImmutableCollection <Flag> flags;
var pres = Factory.Instance.ParseDataTerm(rendered.GetStringValue(), out flags);
Contract.Assert(pres == null || pres.Node.IsFuncOrAtom);
result.AddFlags(flags);
if (pres == null)
{
result.Failed();
return(n);
}
else
{
return(pres.Node);
}
}
Node resultNode = n;
//// TODO: This could be a performance bottle-neck if many children
//// have children with quotations. In this case, a new ShallowClone
//// function must implemented, which simultaneously replaces many children.
bool mF, mC;
int pos = 0;
using (var itF = folds.GetEnumerator())
{
using (var itC = n.Children.GetEnumerator())
{
while ((mF = itF.MoveNext()) & (mC = itC.MoveNext()))
{
if (itF.Current != itC.Current)
{
resultNode = resultNode.ShallowClone(itF.Current, pos);
}
++pos;
}
Contract.Assert(!mF && !mC);
}
}
return(resultNode);
}
