using System;

using System.Linq.Expressions;

using FastExpressionCompiler;

​

public static class Numbers

{

    public static int GetInt() => 40;

    public static int AddTwo(ref int value) => value + 2;

}

​

public class Program

{

    public static void Main()

    {

        var useFastCompile = true; // USE FASTCOMPILE

        var result1 = CompileAndExecute( CallWithAssign(), useFastCompile );

        Console.WriteLine( $"Call Assign: {result1}" );  

        var result2 = CompileAndExecute( CallInline(), useFastCompile ); 

        Console.WriteLine( $"Call Inline: {result2}");  

    }

​

    public static int CompileAndExecute( Expression expr, bool useFastCompile )

    {

        var lambda = useFastCompile

            ? Expression.Lambda<Func<int>>(expr).CompileFast()

            : Expression.Lambda<Func<int>>(expr).Compile();

        var result = lambda();

​

        return result;

    }

    public static Expression CallInline() 

    {

        var getIntMethod = typeof(Numbers).GetMethod(nameof(Numbers.GetInt));

        var addTwoMethod = typeof(Numbers).GetMethod(nameof(Numbers.AddTwo));

        var getIntCall = Expression.Call(getIntMethod);

​

        return Expression.Call(addTwoMethod, getIntCall);  

    }

    public static Expression CallWithAssign() 

    {

        var getIntMethod = typeof(Numbers).GetMethod(nameof(Numbers.GetInt));

        var addTwoMethod = typeof(Numbers).GetMethod(nameof(Numbers.AddTwo));

​

        var getIntCall = Expression.Call(getIntMethod);

        var variable = Expression.Variable(typeof(int), "local");

        var assignToVar = Expression.Assign(variable, getIntCall);

        var addTwoCall = Expression.Call(addTwoMethod, variable);

​

        var block = Expression.Block(

            new[] { variable },

            assignToVar,       

            addTwoCall         

        );

​

        return block;

    }

}