3 files changed, 595 insertions, 0 deletions
diff --git a/base/src/main/java/bjc/utils/graph/AdjacencyMap.java b/base/src/main/java/bjc/utils/graph/AdjacencyMap.java
new file mode 100644
index 0000000..446ab5b
--- /dev/null
+++ b/base/src/main/java/bjc/utils/graph/AdjacencyMap.java
@@ -0,0 +1,216 @@
+package bjc.utils.graph;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+import bjc.utils.data.IHolder;
+import bjc.utils.data.Identity;
+import bjc.utils.funcdata.FunctionalList;
+import bjc.utils.funcdata.FunctionalMap;
+import bjc.utils.funcdata.IList;
+import bjc.utils.funcdata.IMap;
+import bjc.utils.funcutils.FuncUtils;
+
+/**
+ * An adjacency map representing a graph
+ *
+ * @author ben
+ *
+ * @param <T>
+ *                The type of the nodes in the graph
+ */
+public class AdjacencyMap<T> {
+	/**
+	 * Create an adjacency map from a stream of text
+	 *
+	 * @param stream
+	 *                The stream of text to read in
+	 * @return An adjacency map defined by the text
+	 */
+	public static AdjacencyMap<Integer> fromStream(final InputStream stream) {
+		if (stream == null) throw new NullPointerException("Input source must not be null");
+
+		// Create the adjacency map
+		AdjacencyMap<Integer> adjacency;
+
+		try (Scanner input = new Scanner(stream)) {
+			input.useDelimiter("\n");
+
+			int vertexCount;
+
+			final String possible = input.next();
+
+			try {
+				// First, read in number of vertices
+				vertexCount = Integer.parseInt(possible);
+			} catch (final NumberFormatException nfex) {
+				final InputMismatchException imex = new InputMismatchException(
+						"The first line must contain the number of vertices. " + possible
+								+ " is not a valid number");
+
+				imex.initCause(nfex);
+
+				throw imex;
+			}
+
+			if (vertexCount <= 0)
+				throw new InputMismatchException("The number of vertices must be greater than 0");
+
+			final IList<Integer> vertices = new FunctionalList<>();
+
+			FuncUtils.doTimes(vertexCount, (vertexNo) -> vertices.add(vertexNo));
+
+			adjacency = new AdjacencyMap<>(vertices);
+
+			final IHolder<Integer> row = new Identity<>(0);
+
+			input.forEachRemaining((strang) -> {
+				readRow(adjacency, vertexCount, row, strang);
+			});
+		}
+
+		return adjacency;
+	}
+
+	private static void readRow(final AdjacencyMap<Integer> adjacency, final int vertexCount,
+			final IHolder<Integer> row, final String strang) {
+		final String[] parts = strang.split(" ");
+
+		if (parts.length != vertexCount)
+			throw new InputMismatchException("Must specify a weight for all " + vertexCount + " vertices");
+
+		int column = 0;
+
+		for (final String part : parts) {
+			int weight;
+
+			try {
+				weight = Integer.parseInt(part);
+			} catch (final NumberFormatException nfex) {
+				final InputMismatchException imex = new InputMismatchException(
+						"" + part + " is not a valid weight.");
+
+				imex.initCause(nfex);
+
+				throw imex;
+			}
+
+			adjacency.setWeight(row.getValue(), column, weight);
+
+			column++;
+		}
+
+		row.transform((rowNumber) -> rowNumber + 1);
+	}
+
+	/**
+	 * The backing storage of the map
+	 */
+	private final IMap<T, IMap<T, Integer>> adjacency = new FunctionalMap<>();
+
+	/**
+	 * Create a new map from a set of vertices
+	 *
+	 * @param vertices
+	 *                The set of vertices to create a map from
+	 */
+	public AdjacencyMap(final IList<T> vertices) {
+		if (vertices == null) throw new NullPointerException("Vertices must not be null");
+
+		vertices.forEach(vertex -> {
+			final IMap<T, Integer> row = new FunctionalMap<>();
+
+			vertices.forEach(target -> {
+				row.put(target, 0);
+			});
+
+			adjacency.put(vertex, row);
+		});
+	}
+
+	/**
+	 * Check if the graph is directed
+	 *
+	 * @return Whether or not the graph is directed
+	 */
+	public boolean isDirected() {
+		final IHolder<Boolean> result = new Identity<>(true);
+
+		adjacency.forEach((sourceKey, sourceValue) -> {
+			sourceValue.forEach((targetKey, targetValue) -> {
+				final int inverseValue = adjacency.get(targetKey).get(sourceKey);
+
+				if (targetValue != inverseValue) {
+					result.replace(false);
+				}
+			});
+		});
+
+		return result.getValue();
+	}
+
+	/**
+	 * Set the weight of an edge
+	 *
+	 * @param source
+	 *                The source node of the edge
+	 * @param target
+	 *                The target node of the edge
+	 * @param weight
+	 *                The weight of the edge
+	 */
+	public void setWeight(final T source, final T target, final int weight) {
+		if (source == null)
+			throw new NullPointerException("Source vertex must not be null");
+		else if (target == null) throw new NullPointerException("Target vertex must not be null");
+
+		if (!adjacency.containsKey(source))
+			throw new IllegalArgumentException("Source vertex " + source + " isn't present in map");
+		else if (!adjacency.containsKey(target))
+			throw new IllegalArgumentException("Target vertex " + target + " isn't present in map");
+
+		adjacency.get(source).put(target, weight);
+	}
+
+	/**
+	 * Convert this to a different graph representation
+	 *
+	 * @return The new representation of this graph
+	 */
+	public Graph<T> toGraph() {
+		final Graph<T> ret = new Graph<>();
+
+		adjacency.forEach((sourceKey, sourceValue) -> {
+			sourceValue.forEach((targetKey, targetValue) -> {
+				ret.addEdge(sourceKey, targetKey, targetValue, true);
+			});
+		});
+
+		return ret;
+	}
+
+	/**
+	 * Convert an adjacency map back into a stream
+	 *
+	 * @param sink
+	 *                The stream to convert to
+	 */
+	public void toStream(final OutputStream sink) {
+		if (sink == null) throw new NullPointerException("Output source must not be null");
+
+		final PrintStream outputPrinter = new PrintStream(sink);
+
+		adjacency.forEach((sourceKey, sourceValue) -> {
+			sourceValue.forEach((targetKey, targetValue) -> {
+				outputPrinter.printf("%d", targetValue);
+			});
+
+			outputPrinter.println();
+		});
+
+		outputPrinter.close();
+	}
+}
diff --git a/base/src/main/java/bjc/utils/graph/Edge.java b/base/src/main/java/bjc/utils/graph/Edge.java
new file mode 100644
index 0000000..0152e3d
--- /dev/null
+++ b/base/src/main/java/bjc/utils/graph/Edge.java
@@ -0,0 +1,112 @@
+package bjc.utils.graph;
+
+/**
+ * An edge in a weighted graph
+ *
+ * @author ben
+ *
+ * @param <T>
+ *                The type of the nodes in the graph
+ */
+public class Edge<T> {
+	/*
+	 * The distance from initial to terminal node
+	 */
+	private final int distance;
+
+	/*
+	 * The initial and terminal nodes of this edge
+	 */
+	private final T source, target;
+
+	/**
+	 * Create a new edge with set parameters
+	 *
+	 * @param initial
+	 *                The initial node of the edge
+	 * @param terminal
+	 *                The terminal node of the edge
+	 * @param distance
+	 *                The distance between initial and terminal edge
+	 */
+	public Edge(final T initial, final T terminal, final int distance) {
+		if (initial == null)
+			throw new NullPointerException("Initial node must not be null");
+		else if (terminal == null) throw new NullPointerException("Terminal node must not be null");
+
+		this.source = initial;
+		this.target = terminal;
+		this.distance = distance;
+	}
+
+	@Override
+	public boolean equals(final Object obj) {
+		if (this == obj)
+			return true;
+		else if (obj == null)
+			return false;
+		else if (getClass() != obj.getClass())
+			return false;
+		else {
+			final Edge<?> other = (Edge<?>) obj;
+
+			if (distance != other.distance)
+				return false;
+			else if (source == null) {
+				if (other.source != null) return false;
+			} else if (!source.equals(other.source))
+				return false;
+			else if (target == null) {
+				if (other.target != null) return false;
+			} else if (!target.equals(other.target)) return false;
+
+			return true;
+		}
+	}
+
+	/**
+	 * Get the distance in this edge
+	 *
+	 * @return The distance between the initial and terminal nodes of this
+	 *         edge
+	 */
+	public int getDistance() {
+		return distance;
+	}
+
+	/**
+	 * Get the initial node of an edge
+	 *
+	 * @return The initial node of this edge
+	 */
+	public T getSource() {
+		return source;
+	}
+
+	/**
+	 * Get the target node of an edge
+	 *
+	 * @return The target node of this edge
+	 */
+	public T getTarget() {
+		return target;
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+
+		int result = 1;
+
+		result = prime * result + distance;
+		result = prime * result + (source == null ? 0 : source.hashCode());
+		result = prime * result + (target == null ? 0 : target.hashCode());
+
+		return result;
+	}
+
+	@Override
+	public String toString() {
+		return " first vertex " + source + " to vertex " + target + " with distance: " + distance;
+	}
+}
diff --git a/base/src/main/java/bjc/utils/graph/Graph.java b/base/src/main/java/bjc/utils/graph/Graph.java
new file mode 100644
index 0000000..280a7f5
--- /dev/null
+++ b/base/src/main/java/bjc/utils/graph/Graph.java
@@ -0,0 +1,267 @@
+package bjc.utils.graph;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.PriorityQueue;
+import java.util.Queue;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BiPredicate;
+
+import bjc.utils.data.IHolder;
+import bjc.utils.data.Identity;
+import bjc.utils.funcdata.FunctionalMap;
+import bjc.utils.funcdata.IList;
+import bjc.utils.funcdata.IMap;
+
+/**
+ * A directed weighted graph, where the vertices have some arbitrary label
+ *
+ * @author ben
+ *
+ * @param <T>
+ *                The label for vertices
+ */
+public class Graph<T> {
+	/**
+	 * 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> Graph<E> fromEdgeList(final List<Edge<E>> edges) {
+		final Graph<E> 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 IMap<T, IMap<T, Integer>> backing;
+
+	/**
+	 * Create a new 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 distance
+	 *                The distance from the source vertex to the target
+	 *                vertex
+	 * @param directed
+	 *                Whether or not
+	 */
+	public void addEdge(final T source, final T target, final int distance, 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<T, Integer>());
+		}
+
+		// Add the edge to the graph
+		backing.get(source).put(target, distance);
+
+		// Handle possible directed edges
+		if (!directed) {
+			if (!backing.containsKey(target)) {
+				backing.put(target, new FunctionalMap<T, Integer>());
+			}
+
+			backing.get(target).put(source, distance);
+		}
+	}
+
+	/**
+	 * 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 T source, final BiPredicate<T, Integer> matcher,
+			final BiConsumer<T, Integer> 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, weight) -> {
+			if (matcher.test(target, weight)) {
+				action.accept(target, weight);
+			}
+		});
+	}
+
+	/**
+	 * 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 IMap<T, Integer> getEdges(final T 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 the initial vertex of the graph
+	 *
+	 * @return The initial vertex of the graph
+	 */
+	public T getInitial() {
+		return backing.keyList().first();
+	}
+
+	/**
+	 * Uses Prim's algorothm to calculate a MST for the graph.
+	 *
+	 * If the graph is non-connected, this will lead to unpredictable
+	 * results.
+	 *
+	 * @return a list of edges that constitute the MST
+	 */
+	public List<Edge<T>> getMinimumSpanningTree() {
+		// Set of all of the currently available edges
+		final Queue<Edge<T>> available = new PriorityQueue<>(10,
+				(left, right) -> left.getDistance() - right.getDistance());
+
+		// The MST of the graph
+		final List<Edge<T>> minimums = new ArrayList<>();
+
+		// The set of all of the visited vertices.
+		final Set<T> visited = new HashSet<>();
+
+		// Start at the initial vertex and visit it
+		final IHolder<T> source = new Identity<>(getInitial());
+
+		visited.add(source.getValue());
+
+		// Make sure we visit all the nodes
+		while (visited.size() != getVertexCount()) {
+			// Grab all edges adjacent to the provided edge
+
+			forAllEdgesMatchingAt(source.getValue(), (target, weight) -> {
+				return !visited.contains(target);
+			}, (target, weight) -> {
+				final T vert = source.unwrap(vertex -> vertex);
+
+				available.add(new Edge<>(vert, target, weight));
+			});
+
+			// Get the edge with the minimum distance
+			final IHolder<Edge<T>> minimum = new Identity<>(available.poll());
+
+			// Only consider edges where we haven't visited the
+			// target of
+			// the edge
+			while (visited.contains(minimum.getValue().getTarget())) {
+				minimum.transform((edge) -> available.poll());
+			}
+
+			// Add it to our MST
+			minimums.add(minimum.getValue());
+
+			// Advance to the next node
+			source.transform((vertex) -> minimum.unwrap(edge -> edge.getTarget()));
+
+			// Visit this node
+			visited.add(source.getValue());
+		}
+
+		return minimums;
+	}
+
+	/**
+	 * 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 IList<T> 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 T source, final T 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))
+			throw new NoSuchElementException("vertex " + source + " does not exist.");
+
+		if (!backing.containsKey(target))
+			throw new NoSuchElementException("vertex " + target + " does not exist.");
+
+		backing.get(source).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<T> toAdjacencyMap() {
+		final AdjacencyMap<T> adjacency = new AdjacencyMap<>(backing.keyList());
+
+		backing.forEach((sourceKey, sourceValue) -> {
+			sourceValue.forEach((targetKey, targetValue) -> {
+				adjacency.setWeight(sourceKey, targetKey, targetValue);
+			});
+		});
+
+		return adjacency;
+	}
+}