de.grogra.graph
Interface Path

All Known Implementing Classes:

ArrayPath

public interface Path

A Path consists of an alternating sequence of nodes and edges (starting with a node) of a graph. An edge of a graph is incident with its neighbouring nodes in the path.

The nodes and edges of this path are accessed using their index. Because a path starts with a node, nodes have even indices, while edges haves odd indices. If the index parameter to one of the methods of Path is negative, it is interpreted as an index relative to the end of the path, i.e., the actual index is path.getNodeAndEdgeCount () + index.

Author:

Ole Kniemeyer

Field Summary

static Path[]

PATH_0 A constant array of length 0.

Method Summary

int	getEdgeBits(int index) Returns the edge bits (see Graph.getEdgeBits(Object)) of the edge at index.
Graph	getGraph() Returns the graph which contains this path.
int	getNodeAndEdgeCount() Returns the number of nodes and edges of this path.
java.lang.Object	getObject(int index) Returns the node or edge at index.
long	getObjectId(int index)
boolean	isInEdgeDirection(int index) Checks whether the path traverses the edge at index in edge direction or in reverse edge direction.
boolean	isInstancingEdge(int index)

Field Detail

PATH_0

static final Path[] PATH_0

A constant array of length 0.

Method Detail

getEdgeBits

int getEdgeBits(int index)

Returns the edge bits (see Graph.getEdgeBits(Object)) of the edge at index. If index is negative, it is relative to the end of the list, i.e., it is incremented by getNodeAndEdgeCount(). The actual index has to be odd because edges have odd indices.

Parameters:

index - edge index

Returns:

edge bits of edge

getGraph

Graph getGraph()

Returns the graph which contains this path.

Returns:

graph of path

getNodeAndEdgeCount

int getNodeAndEdgeCount()

Returns the number of nodes and edges of this path. If this is even, the path ends in an edge; if this is odd, the path ends in a node.

Returns:

number of nodes and edges

getObject

java.lang.Object getObject(int index)

Returns the node or edge at index. Because a path always starts with a node, even values of index address nodes, while odd values address edges. Edges may be returned as null, in this case only the information provided by getEdgeBits(int) and isInEdgeDirection(int) is available for the edge. If index is negative, it is relative to the end of the list, i.e., it is incremented by getNodeAndEdgeCount().

Parameters:

index - node or edge index

Returns:

node or edge at index

getObjectId

long getObjectId(int index)

isInEdgeDirection

boolean isInEdgeDirection(int index)

Checks whether the path traverses the edge at index in edge direction or in reverse edge direction. If index is negative, it is relative to the end of the list, i.e., it is incremented by getNodeAndEdgeCount(). The actual index has to be odd because edges have odd indices.

Parameters:

index - edge index

Returns:

true iff path traverses edge in its direction

isInstancingEdge

boolean isInstancingEdge(int index)