Package org.graph4j.traversal

Class TopologicalOrderIterator

java.lang.Object

org.graph4j.traversal.TopologicalOrderIterator

All Implemented Interfaces:

IntIterator

public class TopologicalOrderIterator
extends Object
implements IntIterator

A topological order iterator for a directed acyclic graph (DAG). In a topological ordering, each vertex appears before all the other vertices it has an outgoing edge to. If the input digraph is not acyclic, the hasNext() method will throw an IllegalArgumentException when the ordering cannot be continued, without being complete.

Author:

Cristian Frăsinaru

Constructor Summary

Constructors

Constructor	Description
TopologicalOrderIterator(Digraph graph)	Creates a topological order iterator for a directed graph.

Method Summary

Modifier and Type	Method	Description
boolean	hasNext()	Returns true if the iteration has more elements.
int	level()	Returns the level of the current vertex (the one returned by the next() method.
int	next()	Returns the next element in the iteration.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.graph4j.util.IntIterator

remove

Constructor Details

TopologicalOrderIterator

public TopologicalOrderIterator(Digraph graph)

Creates a topological order iterator for a directed graph.

Parameters:

graph - the input directed graph.

Method Details

hasNext

public boolean hasNext()
                throws IllegalArgumentException

Returns true if the iteration has more elements.

Specified by:

hasNext in interface IntIterator

Returns:

true if the iteration has more elements.

Throws:

IllegalArgumentException - if the digraph is not acyclic.

next

public int next()

Description copied from interface: IntIterator

Returns the next element in the iteration.

Specified by:

next in interface IntIterator

Returns:

the next element in the iteration.

level

public int level()

Returns the level of the current vertex (the one returned by the next() method.

Returns:

the level of the current vertex.