IExpressionTreeNode InjectInto(PredicateNode target, Func<IPredicateConnectiveNode> createConnectiveNode)
{
var source = this;
var targetParent = target.Parent;
//# target is child of source, do nothing
if (object.Equals(target.Parent, source))
return FindRoot();
//# target and this are children of same parent -> swap places
if(targetParent != null && object.Equals(targetParent, source.Parent))
{
targetParent.SwapChildren();
return FindRoot();
}
var originalTargetPosition = default(ChildNodePosition);
if(targetParent != null)
{
originalTargetPosition = targetParent.GetChildPosition(target);
}
bool targetIsDescendantOfSource = target.IsDescendantOf(source);
if(targetIsDescendantOfSource)
{
// target is a descendant of source
// before source is injected into a parent of a target (because target is a Predicate Node, source cannot be injected into it directly)
// attach target parent to parent of source
var targetGrandParent = targetParent.Parent;
targetGrandParent.ClearChildAssignment(targetParent);
targetParent.AssignParent(source.Parent);
if(source.Parent != null)
source.Parent.ReplaceChildNode(source, targetParent);
}
else
{
if (source.Parent != null)
{
source.Parent.ClearChildAssignment(source);
source.AssignParent(null);
}
}
//# check if source has an empty child slot
if(source.Left == null || source.Right == null)
{
// connect target to source
// connect source to target parent
source.AssignParent(targetParent);
targetParent.ReplaceChildNode(target, source);
target.AssignParent(source);
if (source.Left == null)
source.AssignChild(target, ChildNodePosition.Left);
else
source.AssignChild(target, ChildNodePosition.Right);
return FindRoot();
}
//# source has both children, create a new connective mode to link target parent, target and source
var newConnective = createConnectiveNode();
newConnective.CopyFrom(this);
newConnective.AssignChild(target, ChildNodePosition.Left);
newConnective.AssignChild(this, ChildNodePosition.Right);
target.AssignParent(newConnective);
targetParent.AssignChild(newConnective, originalTargetPosition);
newConnective.AssignParent(targetParent);
//# update this parent
if (this.Parent != null)
{
this.Parent.ClearChildAssignment(this);
}
this.AssignParent(newConnective);
return FindRoot();
}
