c# 组合模式

结构图：

抽象对象：

    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 depth);
    }

无子节点的：

    class leaf : component
    {
        public leaf(string name)
            : base(name)
        { }
        public override void add(component c)
        {
            //throw new notimplementedexception();
            console.writeline("cannot add to a leaf");
        }
        public override void remove(component c)
        {
            //throw new notimplementedexception();
            console.writeline("cannot remove to a leaf");
        }
        public override void display(int depth)
        {
            //throw new notimplementedexception();
            console.writeline(new string('-', depth) + name);
        }
    }

可以有子结点：

    class composite : component
    {
        private list<component> children = new list<component>();
        public composite(string name)
            : base(name)
        { }
        public override void add(component c)
        {
            //throw new notimplementedexception();
            children.add(c);
        }
        public override void remove(component c)
        {
            //throw new notimplementedexception();
            children.remove(c);
        }
        public override void display(int depth)
        {
            //throw new notimplementedexception();
            console.writeline(new string('-', depth) + name);
            foreach (component component in children)
            {
                component.display(depth + 2);
            }
        }
    }

 主函数调用：

    class program
    {
        static void main(string[] args)
        {
            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 xb"));
            root.add(comp);
            composite comp2 = new composite("composite x");
            comp2.add(new leaf("leaf xya"));
            comp2.add(new leaf("leaf xyb"));
            comp.add(comp2);
            root.display(1);
            console.readkey();
        }
    }