com.salesforce.jgrapht.graph.MaskSubgraph Maven / Gradle / Ivy

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/*
 * (C) Copyright 2007-2017, by France Telecom and Contributors.
 *
 * JGraphT : a free Java graph-theory library
 *
 * This program and the accompanying materials are dual-licensed under
 * either
 *
 * (a) the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation, or (at your option) any
 * later version.
 *
 * or (per the licensee's choosing)
 *
 * (b) the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation.
 */
package com.salesforce.jgrapht.graph;

import java.util.*;
import java.util.function.*;

import com.salesforce.jgrapht.*;

/**
 * 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
 * 
 * @see UndirectedMaskSubgraph
 * @see DirectedMaskSubgraph
 *
 * @author Guillaume Boulmier
 * @since July 5, 2007
 */
public class MaskSubgraph
    extends AbstractGraph
{
    private static final String UNMODIFIABLE = "this graph is unmodifiable";

    protected final Graph base;
    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 mask vertices and edges to exclude in the subgraph. If a vertex/edge is masked, it is
     *        as if it is not in the subgraph.
     * @deprecated in favor of using the constructor with lambdas
     */
    @Deprecated
    public MaskSubgraph(Graph base, MaskFunctor mask)
    {
        this(base, v -> mask.isVertexMasked(v), e -> mask.isEdgeMasked(e));
    }

    /**
     * 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.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 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}
     */
    @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 EdgeFactory getEdgeFactory()
    {
        return base.getEdgeFactory();
    }

    /**
     * {@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 double getEdgeWeight(E edge)
    {
        assert (edgeSet().contains(edge));

        return base.getEdgeWeight(edge);
    }

    /**
     * {@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;
    }
}

// End MaskSubgraph.java