using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    private Switch<int> _switchStatement;

    public void Main()

    {

        _switchStatement = new Switch<int>(GetCases(), () => Console.WriteLine("Does not equal 3, 30, or 300"));

        PrintGetValue(3);

        PrintGetValue(30);

        PrintGetValue(300);

        PrintGetValue(301);

        PrintGetValue(500);

        // Add 500

        _switchStatement.AddCase(500, () => Console.WriteLine("Equals 500"));

        _switchStatement.UpdateDefaultCase(() => Console.WriteLine("Does not equal 3, 30, 300, or 500"));

        PrintGetValue(500);

        PrintGetValue(501);

    }

    private void PrintGetValue(int number)

    {

        Console.Write(number + ": ");

        _switchStatement.GetValue(number)();

    }

    private Dictionary<int, Action> GetCases()

    {

        return new Dictionary<int, Action>

        {

            { 3 ,    () => Console.WriteLine("Equals 3")   },

            { 30 ,   () => Console.WriteLine("Equals 30")  },

            { 300 ,  () => Console.WriteLine("Equals 300") }

        };

    }

    private Dictionary<Func<int, bool>, Action> GetComplexCases()

    {

        return new Dictionary<Func<int, bool>, Action>

        {

            { x => x < 3 ,    () => Console.WriteLine("Smaller than 3")   },

            { x => x < 30 ,   () => Console.WriteLine("Smaller than 30")  },

            { x => x < 300 ,  () => Console.WriteLine("Smaller than 300") }

        };

    }

}

​

public class Switch<T>

{

    private Dictionary<T, Action> Cases;

    private Action DefaultCase;

    public Switch(Dictionary<T, Action> cases, Action defaultCase)

    {

        this.Cases = cases;

        this.DefaultCase = defaultCase;

    }

    public Action GetValue(T key)

    {

        Action keyValue;

        if (Cases.TryGetValue(key, out keyValue))

            return keyValue;

        return DefaultCase;

    }

    public void AddCase(T key, Action caseValue)

    {

        if (Cases.ContainsKey(key))

            return;

        Cases.Add(key, caseValue);

    }

    public void UpdateDefaultCase(Action defaultCase)

    {

        this.DefaultCase = defaultCase;

    }

}