class1.cs

来自DoFactory的设计模式, 由于是本人根据已有代码创建,没有NETOptimized项

// Visitor pattern -- Structural example  

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Visitor.Structural
{

    // MainApp test application 

    class MainApp
    {
        static void Main()
        {
            // Setup structure 
            ObjectStructure o = new ObjectStructure();
            o.Attach(new ConcreteElementA());
            o.Attach(new ConcreteElementB());

            // Create visitor objects 
            ConcreteVisitor1 v1 = new ConcreteVisitor1();
            ConcreteVisitor2 v2 = new ConcreteVisitor2();

            // Structure accepting visitors 
            o.Accept(v1);
            o.Accept(v2);

            // Wait for user 
            Console.Read();
        }
    }

    // "Visitor" 

    abstract class Visitor
    {
        public abstract void VisitConcreteElementA(
          ConcreteElementA concreteElementA);
        public abstract void VisitConcreteElementB(
          ConcreteElementB concreteElementB);
    }

    // "ConcreteVisitor1" 

    class ConcreteVisitor1 : Visitor
    {
        public override void VisitConcreteElementA(
          ConcreteElementA concreteElementA)
        {
            Console.WriteLine("{0} visited by {1}",
              concreteElementA.GetType().Name, this.GetType().Name);
        }

        public override void VisitConcreteElementB(
          ConcreteElementB concreteElementB)
        {
            Console.WriteLine("{0} visited by {1}",
              concreteElementB.GetType().Name, this.GetType().Name);
        }
    }

    // "ConcreteVisitor2" 

    class ConcreteVisitor2 : Visitor
    {
        public override void VisitConcreteElementA(
          ConcreteElementA concreteElementA)
        {
            Console.WriteLine("{0} visited by {1}",
              concreteElementA.GetType().Name, this.GetType().Name);
        }

        public override void VisitConcreteElementB(
          ConcreteElementB concreteElementB)
        {
            Console.WriteLine("{0} visited by {1}",
              concreteElementB.GetType().Name, this.GetType().Name);
        }
    }

    // "Element" 

    abstract class Element
    {
        public abstract void Accept(Visitor visitor);
    }

    // "ConcreteElementA" 

    class ConcreteElementA : Element
    {
        public override void Accept(Visitor visitor)
        {
            visitor.VisitConcreteElementA(this);
        }

        public void OperationA()
        {
        }
    }

    // "ConcreteElementB" 

    class ConcreteElementB : Element
    {
        public override void Accept(Visitor visitor)
        {
            visitor.VisitConcreteElementB(this);
        }

        public void OperationB()
        {
        }
    }

    // "ObjectStructure" 

    class ObjectStructure
    {
        private ArrayList elements = new ArrayList();

        public void Attach(Element element)
        {
            elements.Add(element);
        }

        public void Detach(Element element)
        {
            elements.Remove(element);
        }

        public void Accept(Visitor visitor)
        {
            foreach (Element e in elements)
            {
                e.Accept(visitor);
            }
        }
    }
}