The basic operations interfaces define cornerstone methods or properties, that INSet<T>-derived interfaces reuse via interface inheritance. Although primary intended for NOV Data Structures, the general and simple nature of these interfaces, allows them to be used by other NOV modules (such as Graphics, Layout etc.). The basic operations interfaces are declared as follows:

// Implemented by objects that can be threated as finite or infinite sets of specific items.
public interface INContains<T>
{
    // Queries whether the specified item is contained in this object.
    bool Contains(T item);
}
// Implemented by objects that can provide a count for a specific type of items.
public interface INCountable<T>
{
    // Gets the count of items
    int Count { get; }
}
// Implemented by objects in which you can add items from a specific type.
public interface INAddable<T>
{
    // Adds the specified item
    void Add(T item);
}
// Implemented by objects from which you can remove items from a specific type.
public interface INRemovable<T>
{
    // Removes the specified item
    void Remove(T item);
}
// Implemented by objects from which you can remove all content (items).
public interface INClearable
{
    // Removes all content (items)
    void Clear();
}

The following image illustrates the INSet derived interfaces:

The INSet<T> derived interfaces are logically separating the sets by the following abilities:

• ability for random access - sets in which you can randomly access items at specific index (INIndexedSet<T>).
• ability for dynamic mutation - sets to which you can add items and remove items from (INDynamicSet<T>).
• ability to replace items - sets in which you can replace items at a specific index (INWritableIndexedSet<T>).
• ability to contain duplicate items - in the Sets Theory such sets are called multisets. In NOV we are primary interested in multisets that support random access (INIndexedMultiSet<T>), in order to define IndexOf/LastIndexOf operations.

Following are comments about the interfaces in the INSet<T> hierarchy: