Composite Pattern - [Structural Patterns]

Definition
[Download cs c#]

Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.

    //Component class

    abstract class Component

    {

        protected string name;

        public Component(string name)

        {

            this.name = name;

        }

        public abstract void Add(Component c);

        public abstract void Remove(Component c);

        public abstract void Display(int Dept);

    }

    //Composite Class

    class Composite : Component

    {

        private List<Component> _com = new List<Component>();

        public Composite(string name):base(name)

        {

        }

        public override void Add(Component c)

        {

            _com.Add(c);

        }

        public override void Remove(Component c)

        {

            _com.Remove(c);

        }

        public override void Display(int Dept)

        {

            Console.WriteLine(new String('-',Dept)+name);

            foreach (Component component in _com)

            {

                component.Display(Dept + 2);

            }

        }

    }

        //Leaf Class

        class Leaf : Component

        {

            public Leaf(string name):base(name)

            {

            }

            public override void Add(Component c)

            {

                Console.WriteLine("Can not add to a leaf");

            }

            public override void Remove(Component c)

            {

                Console.WriteLine("Can not remove from a leaf");

            }

            public override void Display(int Dept)

            {

                Console.WriteLine(new String('-', Dept) + name);

            }

        }

            //---Composite Calling...

            Composite root = new Composite("root");

            root.Add(new Leaf("Leaf A"));

            root.Add(new Leaf("Leaf B"));

            Composite comp = new Composite("Composite X");

            comp.Add(new Leaf("Leaf XA"));

            comp.Add(new Leaf("Leaf XAB"));

            root.Add(comp);

            root.Add(new Leaf("Leaf C"));

            // Add and remove a leaf

            Leaf leaf = new Leaf("Leaf D");

            root.Add(leaf);

            root.Remove(leaf);

            // Recursively display tree

            root.Display(1);