using System;

using System.Collections.Generic;

using System.Threading.Tasks;

using System.Linq;

using System.Linq.Expressions;

public class Program

{

    public static  void Main()

    {

        Expression<Func<Event, bool>> searchForLogCorrelationKeyExpression = x => string.Equals(x.A, "A", StringComparison.CurrentCultureIgnoreCase);

        Expression<Func<Event, bool>> searchForLsidExpressionExpression =  x => string.Equals(x.B, "B", StringComparison.CurrentCultureIgnoreCase);

        Expression<Func<Event, bool>> searchForLogLocationExpression = x => string.Equals(x.C, "C", StringComparison.CurrentCultureIgnoreCase);

        var res = searchForLogCorrelationKeyExpression.AndAlso(searchForLsidExpressionExpression).AndAlso(searchForLogLocationExpression);

        Console.WriteLine(res.Compile()(new Event(){A="A",B="B",C="C"}));

    }

}

​

public class Event

{

    public string A {get;set;}

    public string B {get;set;}

    public string C {get;set;}

}

​

​

​

public static class Extensions

{

public static Expression<Func<T, Boolean>> AndAlso<T>(this Expression<Func<T, Boolean>> left, Expression<Func<T, Boolean>> right)

    {

        Expression<Func<T, Boolean>> combined = Expression.Lambda<Func<T, Boolean>>(

            Expression.AndAlso(

                left.Body,

                new ExpressionParameterReplacer(right.Parameters, left.Parameters).Visit(right.Body)

                ), left.Parameters);

                 return combined;

    }

}

public class ExpressionParameterReplacer : ExpressionVisitor

{

    private IDictionary<ParameterExpression, ParameterExpression> ParameterReplacements { get; set; }

​

    public ExpressionParameterReplacer(IList<ParameterExpression> fromParameters, IList<ParameterExpression> toParameters)

    {

        ParameterReplacements = new Dictionary<ParameterExpression, ParameterExpression>();

​

        for(int i = 0; i != fromParameters.Count && i != toParameters.Count; i++)

        { ParameterReplacements.Add(fromParameters[i], toParameters[i]); }

    }

​

    protected override Expression VisitParameter(ParameterExpression node)

    {

        ParameterExpression replacement;

​

        if(ParameterReplacements.TryGetValue(node, out replacement))

        { node = replacement; }

​

        return base.VisitParameter(node);

    }           

}