using System;
using System.Diagnostics;
using System.Linq.Expressions;


namespace ConsoleApp11
{
    class Program
    {
        static void Main(string[] args)
        {
            var c1 = BuildLambda<Class1, int>("Id").Compile();

            for (int i = 0; i < 100_000_000; i += 100_000)
            {
                Stopwatch sw = Stopwatch.StartNew();
                Test1(i);
                var time1 = sw.ElapsedMilliseconds;
                sw = Stopwatch.StartNew();
                Test2(i, c1);
                var time2 = sw.ElapsedMilliseconds;

                var start = $"{i:N0}".PadRight(10);
                Console.WriteLine($"{start} iterations - new: {time1}ms. | func {time2}ms.");

                i *= 5;
            }
        }

        static void Test1(int count)
        {
            for (int i = 0; i < count; i++)
            {
                var t = new Class1() { Id = i };
            }
        }

        static void Test2(int count, Func<int, Class1> c1)
        {
            for (int i = 0; i < count; i++)
            {
                var t = c1.Invoke(i);
            }
        }

        public static Expression<Func<A1, T>> BuildLambda<T, A1>(string param1Name)
        {
            var createdType = typeof(T);
            var param = Expression.Parameter(typeof(A1), param1Name);
            var ctor = Expression.New(createdType);
            var prop = createdType.GetProperty(param1Name);
            var displayValueAssignment = Expression.Bind(prop, param);
            var memberInit = Expression.MemberInit(ctor, displayValueAssignment);

            return
                Expression.Lambda<Func<A1, T>>(memberInit, param);
        }
    }

    public class Class1
    {
        public int Id { get; set; }

        public override string ToString()
        {
            return $"My Id is {Id}";
        }
    }

    public class ExpressionParam
    {
        public ExpressionParam(string name, Type type)
        {
            this.Name = name;
            this.Type = type;
        }
        public string Name { get; set; }

        public Type Type { get; set; }
    }

}