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This artifact provides various common utility operations for analyzing and manipulating automata and graphs, such as traversal, minimization and copying.

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/* Copyright (C) 2013 TU Dortmund
 * This file is part of AutomataLib, http://www.automatalib.net/.
 * 
 * AutomataLib is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 3.0 as published by the Free Software Foundation.
 * 
 * AutomataLib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with AutomataLib; if not, see
 * http://www.gnu.de/documents/lgpl.en.html.
 */
package net.automatalib.util.graphs;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import net.automatalib.commons.util.mappings.Mapping;
import net.automatalib.commons.util.mappings.MutableMapping;
import net.automatalib.graphs.BidirectionalGraph;
import net.automatalib.graphs.Graph;
import net.automatalib.graphs.IndefiniteGraph;
import net.automatalib.graphs.UniversalIndefiniteGraph;
import net.automatalib.util.graphs.traversal.GraphTraversal;


public abstract class Graphs {
			
	public static  Mapping> incomingEdges(final Graph graph) {
		if(graph instanceof BidirectionalGraph)
			return new InEdgesMapping((BidirectionalGraph)graph);
		
		MutableMapping> inEdgesMapping
			= graph.createStaticNodeMapping();
		
		for(N node : graph) {
			Collection outEdges = graph.getOutgoingEdges(node);
			if(outEdges == null)
				continue;
			for(E e : outEdges) {
				N tgt = graph.getTarget(e);
				Collection inEdges = inEdgesMapping.get(tgt);
				if(inEdges == null) {
					inEdges = new ArrayList();
					inEdgesMapping.put(tgt, inEdges);
				}
				inEdges.add(e);
			}
		}
		
		return inEdgesMapping;
	}
	
	public static  Path findShortestPath(final IndefiniteGraph graph, int limit, N start, Collection targets) {
		FindShortestPathVisitor vis = new FindShortestPathVisitor(graph, targets);
		
		GraphTraversal.breadthFirst(graph, limit, Collections.singleton(start), vis);
		
		if(!vis.wasSuccessful())
			return null;
		
		return vis.getTargetPath().toPath(graph);
	}
	
	
	public static  Mapping nodeProperties(final UniversalIndefiniteGraph graph) {
		return new Mapping() {
			@Override
			public NP get(N elem) {
				return graph.getNodeProperty(elem);
			}
		};
	}
	
	public static  Mapping edgeProperties(final UniversalIndefiniteGraph graph) {
		return new Mapping() {
			@Override
			public EP get(E elem) {
				return graph.getEdgeProperty(elem);
			}
		};
	}
	
	private Graphs() {}
}