Exercise 2: Entities, Relationships, and Values

Design an Entity class

An entity can have an id

Implement Set method which allows a property of an entity to be given a value. For the time being, implement words as entities whos IDs are surrounded by single quotes. ex. 'Daniel'

Implement a Get method which returns the value of a entity's property

Implement an AddRelationship method

Design a Relationship class as a subclass of Entity

Design a Brain class which allows entities to be created via CreateEntity and relationships to be created using CreateEntity. Make the Entity and Relationship classes internal to this class and expose their functionality with the interfaces IEntity and IRelationship.

Enforce entity IDs, if specified, to be unique.

Pass the following test case:

[Test] public void Test1() {    IEntity is_a = Brain.CreateEntity("is_a");    IEntity has_a = Brain.CreateEntity("has_a");    IEntity Daniel = Brain.CreateEntity("Daniel");    IEntity person = Brain.CreateEntity("person");    Brain.CreateRelationship(Daniel, is_a, person);    IEntity first_name = Brain.CreateEntity("first_name");    Brain.CreateRelationship(person, has_a, first_name);    IEntity wDaniel = Brain.CreateEntity("'Daniel'");    Daniel.Set(first_name, wDaniel);    Assert.AreEqual("'Daniel'", Daniel.Get(first_name).Id); }}