1 files changed, 62 insertions, 0 deletions
diff --git a/src/main/java/bjc/data/Context.java b/src/main/java/bjc/data/Context.java
new file mode 100644
index 0000000..7efdc4d
--- /dev/null
+++ b/src/main/java/bjc/data/Context.java
@@ -0,0 +1,62 @@
+package bjc.data;
+
+/**
+ * Represents a 'context' which is a hierarchical set of objects.
+ * @author Ben Culkin
+ *
+ */
+public interface Context {
+	/**
+	 * Register an object with this context.
+	 * 
+	 * @param name The name of the object.
+	 * @param o The object to register.
+	 */
+	void register(String name, Object o);
+
+	/**
+	 * Get the parent of this context.
+	 * 
+	 * @return The parent of this context.
+	 */
+	Context getParent();
+
+	/**
+	 * Get an object from this context.
+	 * 
+	 * @param name The name of the object.
+	 * 
+	 * @return The object bound to that name.
+	 */
+	Object get(String name);
+	
+	/**
+	 * Get an object which is an instance of the provided class or a subclass
+	 * thereof.
+	 * 
+	 * @param <T> The type of the object.
+	 * 
+	 * @param contract The class of the object.
+	 * 
+	 * @return An instance of the provided class.
+	 */
+	<T> T get(Class<T> contract);
+	
+	/**
+	 * Get a named object which is an instance of the provided class or a subclass
+	 * thereof.
+	 * 
+	 * @param <T> The type of the object.
+	 * 
+	 * @param name The name of the object
+	 * @param contract The class of the object.
+	 * 
+	 * @return An instance of the provided class, with the given name..
+	 */
+	default <T> T get(String name, Class<T> contract) {
+		Object obj = get(name);
+		return obj == null 
+				? getParent().get(name, contract) 
+						: contract.cast(obj);
+	};
+}