net.walend.digraph
Interface UEDigraph

All Superinterfaces:

HasState

All Known Subinterfaces:

MutableUEDigraph

All Known Implementing Classes:

AbstractHashUEDigraph, MutableHashUEDigraph

public interface UEDigraph

extends HasState

UEDigraph is an interface for representing directed graphs of nodes linked by zero or one edge. Each node and edge must be a unique Object in the digraph. Reusing edges and nodes may produce unpredictable results.

By default, this digraph uses equals() as the method to determine identity. Persistent versions may use hasSameIdentity() instead, for example.

One could create a subclass of UEDigraph that will work with zero or more edges by extending this interface. I have not done that.

Direct implementations of UEDigraph should have a single constructor that takes a UEDigraph as a parameter. Some implementations should provide a view of this UEDigraph, by implementing the net.walend.collection.View interface. Others should copy the parameter to produced an immutable UEDigraph.

Since:

20010612

Author:

David Walend

Field Summary

static UEDigraph

EMPTY

Method Summary

boolean	containsEdge(java.lang.Object edge) Returns true if edge exists in the digraph anywhere
boolean	containsEdge(java.lang.Object fromNode, java.lang.Object toNode) Returns true if the digraph contains any edge from fromNode to toNode
boolean	containsEdge(java.lang.Object fromNode, java.lang.Object toNode, java.lang.Object edge) Returns true if edge links fromNode to toNode
boolean	containsEdges(Set edges)
boolean	containsNode(java.lang.Object node)
boolean	containsNodes(Set nodes)
boolean	containsUEDigraph(UEDigraph digraph) Returns true if digraph is a subgraph of this UEDigraph.
int	countInboundEdges(java.lang.Object node)
int	countOutboundEdges(java.lang.Object node)
int	edgeCount()
EdgeIterator	edgeIterator()
java.lang.Object	getEdge(java.lang.Object fromNode, java.lang.Object toNode) Returns null if either node is not in the digraph or if no edge links fromNode to toNode
Set	getEdges()
java.lang.Object	getFromNode(java.lang.Object edge)
Set	getFromNodes(java.lang.Object node) Returns the set of nodes that can reach this node by crossing one edge.
Set	getInboundEdges(java.lang.Object node) Returns the empty set if node is not in the digraph, or if node has no inbound edges.
Set	getNodes()
Set	getOutboundEdges(java.lang.Object node) Returns the empty set if node is not in the digraph, or if node has no outbound edges.
java.lang.Object	getToNode(java.lang.Object edge)
Set	getToNodes(java.lang.Object node) Returns the set of nodes that can be reached from this node by crossing one edge.
UEDigraph	intersectWithUEDigraph(UEDigraph digraph) Returns a new digraph that is the intersection of this with digraph.
boolean	isEdgeFree() Returns true if this UEDigraph has no edges.
boolean	isEmpty()
int	nodeCount()
java.util.Iterator	nodeIterator() Implementations should explicitly state how they interpret nodeIterator()'s remove method.
boolean	sameUEDigraphAs(UEDigraph digraph) Returns true if digraph is the same as this; that is, if this.containsUEDigraph(digraph) and digraph.containsUEDigraph(this).
UEDigraph	unionUEDigraph(UEDigraph digraph) Returns a new digraph that is the union of this with digraph.

Methods inherited from interface net.walend.collection.HasState

getPrincipleInterface, sameStateAs

Field Detail

EMPTY

public static final UEDigraph EMPTY

Method Detail

nodeCount

public int nodeCount()

edgeCount

public int edgeCount()

isEmpty

public boolean isEmpty()

containsNode

public boolean containsNode(java.lang.Object node)

containsEdge

public boolean containsEdge(java.lang.Object fromNode,
                            java.lang.Object toNode)
                     throws NodeMissingException

Returns true if the digraph contains any edge from fromNode to toNode

Throws:

NodeMissingException - if either node is missing from the digraph.

containsEdge

public boolean containsEdge(java.lang.Object fromNode,
                            java.lang.Object toNode,
                            java.lang.Object edge)
                     throws NodeMissingException

Returns true if edge links fromNode to toNode

Throws:

NodeMissingException - if either node is missing from the digraph.

containsEdge

public boolean containsEdge(java.lang.Object edge)

Returns true if edge exists in the digraph anywhere

countInboundEdges

public int countInboundEdges(java.lang.Object node)
                      throws NodeMissingException

Throws:

NodeMissingException - if node is not in the digraph.

countOutboundEdges

public int countOutboundEdges(java.lang.Object node)
                       throws NodeMissingException

Throws:

NodeMissingException - if node is not in the digraph.

getInboundEdges

public Set getInboundEdges(java.lang.Object node)
                    throws NodeMissingException

Returns the empty set if node is not in the digraph, or if node has no inbound edges.

Throws:

NodeMissingException - if node is not in the digraph.

getOutboundEdges

public Set getOutboundEdges(java.lang.Object node)
                     throws NodeMissingException

Returns the empty set if node is not in the digraph, or if node has no outbound edges.

Throws:

NodeMissingException - if node is not in the digraph.

getFromNode

public java.lang.Object getFromNode(java.lang.Object edge)
                             throws EdgeMissingException

Throws:

EdgeMissingException - if the edge is not in the digraph.

getToNode

public java.lang.Object getToNode(java.lang.Object edge)
                           throws EdgeMissingException

Throws:

EdgeMissingException - if the edge is not in the digraph.

getEdge

public java.lang.Object getEdge(java.lang.Object fromNode,
                                java.lang.Object toNode)
                         throws NodeMissingException

Returns null if either node is not in the digraph or if no edge links fromNode to toNode

Throws:

NodeMissingException - if either node is missing from the digraph.

getFromNodes

public Set getFromNodes(java.lang.Object node)
                 throws NodeMissingException

Returns the set of nodes that can reach this node by crossing one edge.

Throws:

NodeMissingException - if node is not in the digraph.

getToNodes

public Set getToNodes(java.lang.Object node)
               throws NodeMissingException

Returns the set of nodes that can be reached from this node by crossing one edge.

Throws:

NodeMissingException - if node is not in the digraph.

nodeIterator

public java.util.Iterator nodeIterator()

Implementations should explicitly state how they interpret nodeIterator()'s remove method. It should either throw an UnsupportedOperationException or cause a hidden side effect of removing edges.

edgeIterator

public EdgeIterator edgeIterator()

getNodes

public Set getNodes()

getEdges

public Set getEdges()

isEdgeFree

public boolean isEdgeFree()

Returns true if this UEDigraph has no edges.

containsNodes

public boolean containsNodes(Set nodes)

containsEdges

public boolean containsEdges(Set edges)

containsUEDigraph

public boolean containsUEDigraph(UEDigraph digraph)

Returns true if digraph is a subgraph of this UEDigraph.

sameUEDigraphAs

public boolean sameUEDigraphAs(UEDigraph digraph)

Returns true if digraph is the same as this; that is, if this.containsUEDigraph(digraph) and digraph.containsUEDigraph(this).

intersectWithUEDigraph

public UEDigraph intersectWithUEDigraph(UEDigraph digraph)

Returns a new digraph that is the intersection of this with digraph. Implementations should generally return the same implementation of UEDigraph as they have themselves.

unionUEDigraph

public UEDigraph unionUEDigraph(UEDigraph digraph)

Returns a new digraph that is the union of this with digraph. Implementations should generally return the same implementation of UEDigraph as they are themselves. If the digraphs contain conflicting edges, then (unless you have a better rule) let digraph's edge win out.