org.jgrapht.graph.MaskSubgraph Maven / Gradle / Ivy
/*
* (C) Copyright 2007-2020, by France Telecom and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.graph;
import org.jgrapht.*;
import java.io.*;
import java.util.*;
import java.util.function.*;
/**
* An unmodifiable subgraph induced by a vertex/edge masking function. The subgraph will keep track
* of edges being added to its vertex subset as well as deletion of edges and vertices. When
* iterating over the vertices/edges, it will iterate over the vertices/edges of the base graph and
* discard vertices/edges that are masked (an edge with a masked extremity vertex is discarded as
* well).
*
* @param the graph vertex type
* @param the graph edge type
*
*/
public class MaskSubgraph
extends
AbstractGraph
implements
Serializable
{
private static final long serialVersionUID = -7397441126669119179L;
private static final String UNMODIFIABLE = "this graph is unmodifiable";
protected final Graph base;
protected final GraphType baseType;
protected final Set edges;
protected final Set vertices;
protected final Predicate vertexMask;
protected final Predicate edgeMask;
/**
* Creates a new induced subgraph. Running-time = O(1).
*
* @param base the base (backing) graph on which the subgraph will be based.
* @param vertexMask vertices to exclude in the subgraph. If a vertex is masked, it is as if it
* is not in the subgraph. Edges incident to the masked vertex are also masked.
* @param edgeMask edges to exclude in the subgraph. If an edge is masked, it is as if it is not
* in the subgraph.
*/
public MaskSubgraph(Graph base, Predicate vertexMask, Predicate edgeMask)
{
super();
this.base = Objects.requireNonNull(base, "Invalid graph provided");
this.baseType = base.getType();
this.vertexMask = Objects.requireNonNull(vertexMask, "Invalid vertex mask provided");
this.edgeMask = Objects.requireNonNull(edgeMask, "Invalid edge mask provided");
this.vertices = new MaskVertexSet<>(base.vertexSet(), vertexMask);
this.edges = new MaskEdgeSet<>(base, base.edgeSet(), vertexMask, edgeMask);
}
/**
* {@inheritDoc}
*/
@Override
public E addEdge(V sourceVertex, V targetVertex)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean addEdge(V sourceVertex, V targetVertex, E edge)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public V addVertex()
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean addVertex(V v)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean containsEdge(E e)
{
return edgeSet().contains(e);
}
/**
* {@inheritDoc}
*/
@Override
public boolean containsVertex(V v)
{
return vertexSet().contains(v);
}
/**
* {@inheritDoc}
*/
@Override
public Set edgeSet()
{
return edges;
}
/**
* {@inheritDoc}
*/
@Override
public Set edgesOf(V vertex)
{
assertVertexExist(vertex);
return new MaskEdgeSet<>(base, base.edgesOf(vertex), vertexMask, edgeMask);
}
/**
* {@inheritDoc}
*
*
* By default this method returns the sum of in-degree and out-degree. The exact value returned
* depends on the type of the underlying graph.
*/
@Override
public int degreeOf(V vertex)
{
if (baseType.isDirected()) {
return inDegreeOf(vertex) + outDegreeOf(vertex);
} else {
int degree = 0;
Iterator it = edgesOf(vertex).iterator();
while (it.hasNext()) {
E e = it.next();
degree++;
if (getEdgeSource(e).equals(getEdgeTarget(e))) {
degree++;
}
}
return degree;
}
}
/**
* {@inheritDoc}
*/
@Override
public Set incomingEdgesOf(V vertex)
{
assertVertexExist(vertex);
return new MaskEdgeSet<>(base, base.incomingEdgesOf(vertex), vertexMask, edgeMask);
}
/**
* {@inheritDoc}
*/
@Override
public int inDegreeOf(V vertex)
{
if (baseType.isUndirected()) {
return degreeOf(vertex);
} else {
return incomingEdgesOf(vertex).size();
}
}
/**
* {@inheritDoc}
*/
@Override
public Set outgoingEdgesOf(V vertex)
{
assertVertexExist(vertex);
return new MaskEdgeSet<>(base, base.outgoingEdgesOf(vertex), vertexMask, edgeMask);
}
/**
* {@inheritDoc}
*/
@Override
public int outDegreeOf(V vertex)
{
if (baseType.isUndirected()) {
return degreeOf(vertex);
} else {
return outgoingEdgesOf(vertex).size();
}
}
/**
* {@inheritDoc}
*/
@Override
public Set getAllEdges(V sourceVertex, V targetVertex)
{
if (containsVertex(sourceVertex) && containsVertex(targetVertex)) {
return new MaskEdgeSet<>(
base, base.getAllEdges(sourceVertex, targetVertex), vertexMask, edgeMask);
} else
return null;
}
/**
* {@inheritDoc}
*/
@Override
public E getEdge(V sourceVertex, V targetVertex)
{
Set edges = getAllEdges(sourceVertex, targetVertex);
if (edges == null) {
return null;
} else {
return edges.stream().findAny().orElse(null);
}
}
/**
* {@inheritDoc}
*/
@Override
public Supplier getVertexSupplier()
{
return base.getVertexSupplier();
}
/**
* {@inheritDoc}
*/
@Override
public Supplier getEdgeSupplier()
{
return base.getEdgeSupplier();
}
/**
* {@inheritDoc}
*/
@Override
public V getEdgeSource(E edge)
{
assert (edgeSet().contains(edge));
return base.getEdgeSource(edge);
}
/**
* {@inheritDoc}
*/
@Override
public V getEdgeTarget(E edge)
{
assert (edgeSet().contains(edge));
return base.getEdgeTarget(edge);
}
/**
* {@inheritDoc}
*/
@Override
public GraphType getType()
{
return baseType.asUnmodifiable();
}
/**
* {@inheritDoc}
*/
@Override
public double getEdgeWeight(E edge)
{
assert (edgeSet().contains(edge));
return base.getEdgeWeight(edge);
}
/**
* {@inheritDoc}
*/
@Override
public void setEdgeWeight(E edge, double weight)
{
assert (edgeSet().contains(edge));
base.setEdgeWeight(edge, weight);
}
/**
* {@inheritDoc}
*/
@Override
public boolean removeAllEdges(Collection edges)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public Set removeAllEdges(V sourceVertex, V targetVertex)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean removeAllVertices(Collection vertices)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean removeEdge(E e)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public E removeEdge(V sourceVertex, V targetVertex)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public boolean removeVertex(V v)
{
throw new UnsupportedOperationException(UNMODIFIABLE);
}
/**
* {@inheritDoc}
*/
@Override
public Set vertexSet()
{
return vertices;
}
}