1 files changed, 83 insertions, 0 deletions
diff --git a/base/src/main/java/bjc/utils/graph/SimpleAlgGraph.java b/base/src/main/java/bjc/utils/graph/SimpleAlgGraph.java
new file mode 100644
index 0000000..2c7ba08
--- /dev/null
+++ b/base/src/main/java/bjc/utils/graph/SimpleAlgGraph.java
@@ -0,0 +1,83 @@
+package bjc.utils.graph;
+
+import java.util.*;
+
+/**
+ * A basic implementation of a directed algebraic graph.
+ * 
+ * @author bjcul
+ *
+ * @param <Vertex> The type of the vertices
+ */
+public class SimpleAlgGraph<Vertex> implements AlgGraph<Vertex, SimpleAlgGraph<?>> {
+	// TODO: consider if some function for labeling edges would make sense
+	private Set<Vertex> vertices;
+	private Map<Vertex, Vertex> edges;
+
+	/**
+	 * Create a new empty graph.
+	 */
+	public SimpleAlgGraph() {
+		vertices = new HashSet<>();
+		edges = new HashMap<>();
+	}
+
+	/**
+	 * Create a new graph with the given vertices, but no edges.
+	 * 
+	 * @param vertexes The vertices for the graph.
+	 */
+	@SafeVarargs
+	public SimpleAlgGraph(Vertex... vertexes) {
+		this();
+
+		for (Vertex vertex : vertexes)
+			vertices.add(vertex);
+	}
+
+	@Override
+	public <B> SimpleAlgGraph<B> empty() {
+		return new SimpleAlgGraph<>();
+	}
+	
+	@Override
+	public <B> SimpleAlgGraph<B> vertex(B val) {
+		return new SimpleAlgGraph<>();
+	}
+	
+	/**
+	 * Overlay a graph onto this one, adding its vertices and edges.
+	 * 
+	 * @param other The graph to overlay
+	 */
+	@Override
+	public void overlay(AlgGraph<Vertex, SimpleAlgGraph<?>> other) {
+		SimpleAlgGraph<Vertex> graph = (SimpleAlgGraph<Vertex>) other;
+		
+		vertices.addAll(graph.vertices);
+		edges.putAll(graph.edges);
+	}
+
+	/**
+	 * Connect a graph to this one, adding its vertices and edges; as well as
+	 * establishing an edge from each node in this graph, to each node in the other
+	 * graph.
+	 * 
+	 * @param other The graph to connect
+	 */
+	@Override
+	public void connect(AlgGraph<Vertex, SimpleAlgGraph<?>> other) {
+		SimpleAlgGraph<Vertex> graph = (SimpleAlgGraph<Vertex>) other;
+	
+		// note: this could be inefficent for large graphs
+		for (Vertex left : vertices) {
+			for (Vertex right : graph.vertices) {
+				edges.put(left, right);
+			}
+		}
+
+		overlay(other);
+	}
+
+
+}
+\ No newline at end of file