/**
* create an identifier for a descendant area.
* as a BinContainerArea can only have one direct child area,
* the only valie identifiers are ones that are at the end of
* thier path, indicating that it identifies this this node,
* or an identifier with its' current element being zero, indicating
* that the current leg of its's path identifies the zero'th and
* only child node.
*/
public override Area GetArea(AreaIdentifier id)
{
if (id.End)
{
return(this);
}
else if (id.Current == 0)
{
id.MoveNext();
return(child.GetArea(id));
}
else
{
throw new InvalidIdentifier();
}
}
/**
* get the right side value.
* the identier is only valid if it is for the child
* node, or one of the child node's descendants. a
* bin container can not have a right side value.
*/
public override Scaled RightSide(AreaIdentifier id)
{
if (id.End)
{
throw new InvalidOperation();
}
else if (id.Current == 0)
{
id.MoveNext();
return(child.RightSide(id));
}
else
{
throw new InvalidIdentifier();
}
}
/**
* get a child area that has a path to this node
* if the identifier is at its's last item, this final step
* in the path, so return this node, otherwise, if the current step
* is valid (less than the size of the child node list, the child
* area at the current position will get the path moved to the next
* position. If the id is not at it's end, and the current item is
* out of range, an invalid id exception is thrown.
*/
public override Area GetArea(AreaIdentifier id)
{
if (id.End)
{
return(this);
}
else if (id.Current < content.Length)
{
Area current = content[id.Current];
id.MoveNext();
return(current.GetArea(id));
}
else
{
throw new InvalidIdentifier();
}
}
/**
* TODO write this up
*/
public override Scaled Origin(AreaIdentifier id)
{
if (id.End)
{
// get the origin for this node.
return(0);
}
else if (id.Current == 0)
{
// get the origin for the child node
id.MoveNext();
return(child.Origin(id));
}
else
{
// bad monkey
throw new InvalidIdentifier();
}
}