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/*
* (C) Copyright 2019-2023, by Semen Chudakov 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.alg.interfaces;
import org.jgrapht.*;
import java.util.*;
/**
* An algorithm which computes shortest paths from all sources to all targets.
*
* @param the graph vertex type
* @param the graph edge type
* @author Semen Chudakov
*/
public interface ManyToManyShortestPathsAlgorithm
extends ShortestPathAlgorithm
{
/**
* Computes shortest paths from all vertices in {@code sources} to all vertices in
* {@code targets}.
*
* @param sources list of sources vertices
* @param targets list of target vertices
* @return computed shortest paths
*/
ManyToManyShortestPaths getManyToManyPaths(Set sources, Set targets);
/**
* A set of paths from all sources vertices to all target vertices.
*
* @param the graph vertices type
* @param the graph edge type
*/
interface ManyToManyShortestPaths
{
/**
* Returns the set of source vertices for which this many-to-many shortest paths were
* computed.
*
* @return the set of source vertices
*/
Set getSources();
/**
* Returns the set of target vertices for which this many-to-many shortest paths were
* computed.
*
* @return the set of target vertices
*/
Set getTargets();
/**
* Return the path from the {@code source} vertex to the {@code target} vertex. If no such
* path exists, null is returned.
*
* @param source source vertex
* @param target target vertex
* @return path between {@code source} and {@code target} or null if no such path exists
*/
GraphPath getPath(V source, V target);
/**
* Return the weight of the path from the {@code source} vertex to the {@code target}vertex
* or {@link Double#POSITIVE_INFINITY} if there is no such path in the graph. The weight of
* the path between a vertex and itself is always zero.
*
* @param source source vertex
* @param target target vertex
* @return the weight of the path between source and sink vertices or
* {@link Double#POSITIVE_INFINITY} in case no such path exists
*/
double getWeight(V source, V target);
}
/**
* Base class for many-to-many shortest paths implementations.
*
* @param the graph vertex type
* @param the graph edge type
*/
abstract class BaseManyToManyShortestPathsImpl
implements ManyToManyShortestPaths
{
/**
* Set of source vertices.
*/
private final Set sources;
/**
* Set of source vertices.
*/
private final Set targets;
@Override
public Set getSources()
{
return sources;
}
@Override
public Set getTargets()
{
return targets;
}
/**
* Constructs an instance for the given {@code sources} and {@code targets}.
*
* @param sources source vertices
* @param targets target vertices
*/
protected BaseManyToManyShortestPathsImpl(Set sources, Set targets)
{
this.sources = sources;
this.targets = targets;
}
/**
* Checks that {@code source} and {@code target} are not null and are present in the
* {@code graph}.
*
* @param source a source vertex
* @param target a target vertex
*/
protected void assertCorrectSourceAndTarget(V source, V target)
{
Objects.requireNonNull(source, "source should not be null!");
Objects.requireNonNull(target, "target should not be null!");
if (!sources.contains(source) || !targets.contains(target)) {
throw new IllegalArgumentException(
"paths between " + source + " and " + target + " is not computed");
}
}
}
}