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Core compiler artifact for the ASTRA Language
There is a newer version: 1.4.3
package graph.algorithm;

import graph.core.AbstractGraphAlgorithm;
import graph.core.Edge;
import graph.core.Graph;
import graph.core.Parameter;
import graph.core.Vertex;
import graph.gui.GraphOverlay;
import graph.util.Heap;
import graph.util.LinkedList;
import graph.util.List;
import graph.util.Position;
import graph.util.PriorityQueue;

import java.awt.Color;
import java.util.HashMap;
import java.util.Map;

public class DijkstraShortestPathAlgorithm extends AbstractGraphAlgorithm {
	@SuppressWarnings("rawtypes")
	private class DijkstraOverlay implements GraphOverlay {
		@Override
		public Color edgeColor(Edge edge) {
			for (Edge e : spEdgeList) {
				if (edge.equals(e)) return Color.RED;
			}
			return Color.BLACK;
		}

		@Override
		public Color vertexColor(Vertex vertex) {
			for (Vertex v : spVertexList) {
				if (vertex.equals(v)) return Color.RED;
			}
			return Color.BLACK;
		}
	}
	
	private List> spVertexList;
	private List> spEdgeList;
	private Graph G;
	private Map, Integer> distanceMap;
	private Map, Position>> positionMap;
	private Map, Edge> parentMap;
	
	public DijkstraShortestPathAlgorithm() {
		super();
		distanceMap = new HashMap, Integer>();
		positionMap = new HashMap, Position>>();
		parentMap = new HashMap, Edge>();
		addParameter(new Parameter("s","Give the start vertex for the algorithm"));
		addParameter(new Parameter("e","Give the end vertex for the algorithm"));
	}
	
	public DijkstraShortestPathAlgorithm(Graph graph) {
		this();
		G = graph;
	}
	
	public void setGraph(Graph graph) {
		G = graph;
	}
	
	public void search(Map> parameters) {
		Vertex s = parameters.get("s");
		
		PriorityQueue> Q = new Heap>();

		spVertexList = new LinkedList>();
		spEdgeList = new LinkedList>();
		
		distanceMap.clear();
		parentMap.clear();
		for (Vertex vertex: G.vertices()) {
			int value = Integer.MAX_VALUE;
			if (vertex.equals(s)) value = 0;
			distanceMap.put(vertex, value);
			Position> p = Q.insert(value, vertex);
			positionMap.put(vertex, p);
		}
		
		while (!Q.isEmpty()) {
			Vertex u = Q.remove();
			for (Edge e : G.incidentEdges(u)) {
				Vertex z = G.opposite(u, e);
				int r = distanceMap.get(u) + Integer.parseInt(e.element().toString());
				if (r < distanceMap.get(z)) {
					distanceMap.put(z, r);
					Q.replaceKey(positionMap.get(z), r);
					parentMap.put(z, e);
				}
			}
		}
		
		// Work out shortest path
		// NOTE: This is the only change to the STP algorithm
		Vertex v = parameters.get("e");
		while (!v.equals(s)) {
			spVertexList.insertFirst(v);
			Edge e = parentMap.get(v);
			spEdgeList.insertFirst(e);
			v = G.opposite(v, e);
		}
		spVertexList.insertFirst(v);
	}
	
	@Override
	public GraphOverlay getOverlay() {
		return new DijkstraOverlay();
	}
}