using System;

using System.Collections.Generic;

using System.Linq;

using System.Linq.Expressions;

using System.Text;

public class Program

{

    public static void Main()

    {

        var sourceList = new List<Person>

        {

            new Person{FirstName = "John", LastName = "Doe", Email = "Jdoe@sample.com"}, 

            new Person{FirstName = "Jane", LastName = "Doe", Email = "JaneDoe@sample.com"},

            new Person{FirstName = "John", LastName = "Adams", Email = "JAdams@sample.com"},

            new Person{FirstName = "Jane", LastName = "Adams", Email = "JanAdams@sample.com"}

        };

        // ignore age

        var searcher = new GhettoSearcher<Person>()

            .Include(source => source.FirstName)

            .Include(source => source.LastName);

        // search 1

        var term = "jane";

        var result = searcher.Search(sourceList, term).ToList();

        OutputResult(term, result);

        // search 2

        term = "Jane doe";

        result = searcher.Search(sourceList, term).ToList();

        OutputResult(term, result);

        // search 3 (we didn't define age so it shouldn't find anything in this particular list)

        term = "21";

        result = searcher.Search(sourceList, term).ToList();

        OutputResult(term, result);

    }

    private static void OutputResult(string term, List<Person> results)

    {

        Console.WriteLine($"The term \"{term}\" returned {results.Count} results:");

        foreach (var result in results)     

            Console.WriteLine($"- {result.FirstName} {result.LastName} ({result.Email})");      

        Console.WriteLine();

    }

}

​

public class GhettoSearcher<T>

{

    private readonly List<Expression<Func<T, object>>> _maps = new List<Expression<Func<T, object>>>();

    public IEnumerable<T> Search(IEnumerable<T> source, string term)

    {

        term = term.ToLower();

        return source.Where(item => Combine(item).Contains(term));

    }   

    public GhettoSearcher<T> Include(Expression<Func<T, object>> property)

    {

        if (_maps.Contains(property))

            throw new ArgumentException("Already defined");

        _maps.Add(property);

        return this;

    }

    private string Combine(T input)

    {

        var sb = new StringBuilder();

        foreach (var map in _maps)

            sb.AppendFormat("{0} ", map.Compile()(input));      

        return sb.ToString().ToLower().Trim();

    }

}

​

public class Person

{

    public string FirstName {get;set;}

    public string LastName {get;set;}

    public string Email {get;set;}

}