package fha.inf3.graph;
import java.util.Set;
public interface Graph {
/**
* Adds a new vertex to this graph. Vertices are unique within a graph.
* @param vertex the new node to be added.
* @return whether a new vertex could be added to this graph.
*/
public boolean addVertex(Object vertex);
/**
* Adds a new edge from the vertex from to the vertex to.
* from and to must already be vertices of this graph.
* If the graph is undirected, then an edge from to to
* from will be inserted as well. There can be no
* multiple edges between two vertices, i.e. if there exists already an
* edge between from and to, nothing will be done.
* @param from add a new edge from the vertex from.
* @param to add a new edge to the vertex to.
* @return false if from or to do not exist or
* if there is already an edge from from to to,
* returns true otherwise (edge was successfully added).
*/
public boolean addEdge(Object from, Object to);
/**
* Removes the edge between the vertex from and to.
* If there is no such vertex or from or to do not
* exist nothing will be done. If the graph is undirected, then the
* edge from to to from will be removed as well.
* @param from remove edge from the vertex from.
* @param to remove edge to the vertex to.
* @return false if from or to do not exist or
* if there was no edge from from to to,
* returns true otherwise (edge between from and to
* was successfully removed).
*/
public boolean removeEdge(Object from, Object to);
/**
* Is this graph directed?
* @return true if the graph is directed, false otherwise
*/
public boolean isDirected();
/**
* Returns the number of vertices of this graph.
* @return the number of vertices.
*/
public int getNofVertices();
/**
* Returns the number of edges in this graph.
* @return the number of edges.
*/
public int getNofEdges();
/**
* Returns a set of all objects refered to by all vertices in this graph.
*/
public Set getVertices();
/**
* Returns a set of all adjacent vertices of vertex.
* @param vertex we are interested in the adjacent vertices of vertex.
* @return a set of all adjacent vertices of vertex.
*/
public Set getAdjacentVertices(Object vertex);
/**
* Creates and returns a copy of this object.
* @return a clone of this graph.
*/
public Object clone();
}