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package bjc.utils.graph;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.function.BiConsumer;
import java.util.function.BiPredicate;
import bjc.funcdata.*;
/**
* A directed weighted graph, where the vertices have some arbitrary label.
*
* @author ben
*
* @param <VertexLabel>
* The label for vertices.
* @param <EdgeLabel> The label for edges
*/
public class Graph<VertexLabel, EdgeLabel> {
/**
* Create a graph from a list of edges.
*
* @param <E>
* The type of data stored in the edges.
*
* @param edges
* The list of edges to build from.
*
* @return A graph built from the provided edge-list.
*/
public static <E, L> Graph<E, L> fromEdgeList(final List<Edge<E, L>> edges) {
final Graph<E, L> g = new Graph<>();
edges.forEach(edge -> {
g.addEdge(edge.getSource(), edge.getTarget(), edge.getDistance(), true);
});
return g;
}
/** The backing representation of the graph. */
private final MapEx<VertexLabel, MapEx<VertexLabel, EdgeLabel>> backing;
/** Create a new empty graph. */
public Graph() {
backing = new FunctionalMap<>();
}
/**
* Add a edge to the graph.
*
* @param source
* The source vertex for this edge.
*
* @param target
* The target vertex for this edge.
*
* @param label
* The distance from the source vertex to the target vertex.
*
* @param directed
* Whether or not the edge is directed or not.
*/
public void addEdge(final VertexLabel source, final VertexLabel target, final EdgeLabel label,
final boolean directed) {
/* Can't add edges with a null source or target. */
if (source == null) throw new NullPointerException("The source vertex cannot be null");
else if (target == null) throw new NullPointerException("The target vertex cannot be null");
/* Initialize adjacency list for vertices if necessary. */
if (!backing.containsKey(source)) backing.put(source, new FunctionalMap<VertexLabel, EdgeLabel>());
/* Add the edge to the graph. */
backing.get(source).get().put(target, label);
/* Handle possible directed edges. */
if (!directed) {
if (!backing.containsKey(target)) {
backing.put(target, new FunctionalMap<VertexLabel, EdgeLabel>());
}
backing.get(target).get().put(source, label);
}
}
/**
* Execute an action for all edges of a specific vertex matching conditions.
*
* @param source
* The vertex to test edges for.
*
* @param matcher
* The conditions an edge must match.
*
* @param action
* The action to execute for matching edges.
*/
public void forAllEdgesMatchingAt(final VertexLabel source,
final BiPredicate<VertexLabel, EdgeLabel> matcher, final BiConsumer<VertexLabel, EdgeLabel> action) {
if (matcher == null) throw new NullPointerException("Matcher must not be null");
else if (action == null) throw new NullPointerException("Action must not be null");
getEdges(source).forEach((target, label) -> {
if (matcher.test(target, label)) action.accept(target, label);
});
}
/**
* Get all the edges that begin at a particular source vertex.
*
* @param source
* The vertex to use as a source.
* @return All of the edges with the specified vertex as a source.
*/
public MapEx<VertexLabel, EdgeLabel> getEdges(final VertexLabel source) {
/* Can't find edges for a null source. */
if (source == null) {
throw new NullPointerException("The source cannot be null.");
} else if (!backing.containsKey(source)) {
throw new IllegalArgumentException("Vertex " + source + " is not in graph");
}
return backing.get(source).get();
}
/**
* Get the initial vertex of the graph.
*
* @return The initial vertex of the graph.
*/
public VertexLabel getInitial() {
return backing.keyList().first();
}
/**
* Get the count of the vertices in this graph.
*
* @return A count of the vertices in this graph.
*/
public int getVertexCount() {
return backing.size();
}
/**
* Get all of the vertices in this graph.
*
* @return A unmodifiable set of all the vertices in the graph.
*/
public ListEx<VertexLabel> getVertices() {
return backing.keyList();
}
/**
* Remove the edge starting at the source and ending at the target.
*
* @param source
* The source vertex for the edge.
*
* @param target
* The target vertex for the edge.
*/
public void removeEdge(final VertexLabel source, final VertexLabel target) {
/* Can't remove things w/ null vertices. */
if (source == null) {
throw new NullPointerException("The source vertex cannot be null");
} else if (target == null) {
throw new NullPointerException("The target vertex cannot be null");
}
/* Can't remove if one vertice doesn't exists. */
if (!backing.containsKey(source)) {
String msg = String.format("vertex %s does not exist", source);
throw new NoSuchElementException(msg);
}
if (!backing.containsKey(target)) {
String msg = String.format("vertex %s does not exist", target);
throw new NoSuchElementException(msg);
}
backing.get(source).get().remove(target);
/*
* Uncomment this to turn the graph undirected
*
* graph.get(target).remove(source);
*/
}
/**
* Convert a graph into a adjacency map/matrix.
*
* @return A adjacency map representing this graph.
*/
public AdjacencyMap<VertexLabel, EdgeLabel> toAdjacencyMap() {
final AdjacencyMap<VertexLabel, EdgeLabel> adjacency = new AdjacencyMap<>(backing.keyList());
backing.forEach((sourceKey, sourceValue) -> {
sourceValue.forEach((targetKey, targetValue) -> {
adjacency.setLabel(sourceKey, targetKey, targetValue);
});
});
return adjacency;
}
}
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