Head First设计模式之访问者模式

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DesignPatterns.Visitor
{
    class Program
    {
        static void Main(string[] args)
        {
            Food a = new Potato();
            Food b = new Peanut();
            
            var combo = new Combo();
            combo.Add(a);
            combo.Add(b);

            Visitor charger = new Charger("张三");  
            Visitor workerOfPharmacy = new WorkerOfPharmacy("李四"); 

            combo.Accpet(charger); 
            Console.WriteLine();
            combo.Accpet(workerOfPharmacy);
        }
    }

    /// <summary>
    /// 抽象访问者
    /// </summary>
    public abstract class Visitor
    {
        protected string name { get; set; }

        public Visitor(string name)
        {
            this.name = name;
        }

        public abstract void visitor(Potato a);

        public abstract void visitor(Peanut b);
    }
    /// <summary>
    /// 具体访问者：张三
    /// </summary>
    public class Charger : Visitor
    {
        public Charger(string name) : base(name) { }

        public override void visitor(Potato a)
        {
            Console.WriteLine("张三：" + this.name + " 取菜 " + a.GetName());
        }

        public override void visitor(Peanut b)
        {
            Console.WriteLine("张三：" + this.name + " 取菜 " + b.GetName());
        }
    }

    /// <summary>
    /// 具体访问者：李四
    /// </summary>
    public class WorkerOfPharmacy : Visitor
    {
        public WorkerOfPharmacy(string name) : base(name) { }
        public override void visitor(Potato a)
        {
            Console.WriteLine("李四：" + this.name + " 取菜 " + a.GetName() );
        }

        public override void visitor(Peanut b)
        {
            Console.WriteLine("李四：" + this.name + " 取菜 " + b.GetName());
        }
    }
    
    /// <summary>
    /// 抽象元素：食物
    /// </summary>
    public abstract class Food
    {
        protected string name { get; set; } 

        public Food()
        {
            name = "我是食物";
        }

        public string GetName()
        {
            return name;
        }
         

        public abstract void Accept(Visitor visitor);
    }

    /// <summary>
    /// 具体元素：土豆
    /// </summary>
    public class Potato : Food
    {
        public Potato()
        { 
            this.name = "土豆"; 
        }

        public override void Accept(Visitor visitor)
        {
            visitor.visitor(this);
        }
    }
    /// <summary>
    /// 具体元素：花生
    /// </summary>
    public class Peanut : Food
    {
        public Peanut()
        { 
            this.name = "花生";
        }

        public override void Accept(Visitor visitor)
        {
            visitor.visitor(this);
        }
    }

    /// <summary>
    /// 具体元素：套餐
    /// </summary>
    public class Combo
    {
        private List<Food> list = new List<Food>();
        public void Accpet(Visitor visitor)
        {
            foreach (var item in list)
            {
                item.Accept(visitor);
            }
        }

        public void Add(Food med)
        {
            list.Add(med);
        }

        public void Remove(Food med)
        {
            list.Remove(med);
        }
    }
}