diva.graphx

Interface NodeAdapter

All Known Implementing Classes:

BasicNodeAdapter

public interface NodeAdapter

A node adapter is used by GraphModel to manipulate node objects in the application's graph data structure. Since GraphModel doesn't know what this data structure is, adapter objects are used to allow it to manipulate this data structure. Typically, an application will implement NodeAdapter once for each distinct type of node in the graph.

This adapter interface assumes certain things about the graph data structure. We have tried to make these assumptions such that it will not be too hard to write adapters for almost all types of graph Each node is connected to a single node at its head and tail (except for hyper-edges, see below). Nodes and edges are contained in a parent object, which can be the root graph, a composite node, or a hyper-edge. The adapter interfaces do not assume anything about whether edges can connect to objects outside of their parent object.

Sometimes, it will be possible to use the adapter to construct a graph that does not make sense for the native data structure. Implementations of the adapter can thrown an exception of this happens. However, there is no need to be regimental about it: the application is also responsible for constructing the interaction that takes place on the graph, and as long as that is built correctly then invalid graph structures should not occur.

Nodes can be composite, in which case they can contain nodes and edges themselves. Whether or not edges that connect to sub-nodes of the composite are parented by the composite, or by the root graph, is something that the adapter interfaces (and GraphModel) are indifferent to.

Version:

$Revision: 1.2 $

Author:

Michael Shilman, John Reekie

Method Summary

Modifier and Type	Method and Description
int	getNodeCount(Object composite) Return a count of the nodes this graph contains.
Object	getParent(Object node) Return the parent of the given node.
Iterator	inEdges(Object node) Return an iterator over the edges coming into the given node.
boolean	isComposite(Object node) Return true if the given node is a composite, that is, it contains other nodes.
Iterator	nodes(Object composite) Return an iterator over the nodes that this graph contains.
Iterator	outEdges(Object node) Return an iterator over the edges coming out of the given node.
void	setParent(Object node, Object parent) Set the graph parent of the given node.

Method Detail

nodes

Iterator nodes(Object composite)

Return an iterator over the nodes that this graph contains.

getParent

Object getParent(Object node)

Return the parent of the given node.

inEdges

Iterator inEdges(Object node)

Return an iterator over the edges coming into the given node.

isComposite

boolean isComposite(Object node)

Return true if the given node is a composite, that is, it contains other nodes.

getNodeCount

int getNodeCount(Object composite)

Return a count of the nodes this graph contains.

outEdges

Iterator outEdges(Object node)

Return an iterator over the edges coming out of the given node.

setParent

void setParent(Object node,
               Object parent)

Set the graph parent of the given node. Implementors of this method are also responsible for insuring that it is set properly as the child of the parent.