using System;

using System.Collections.Generic;

using System.Linq.Expressions;

using ExpressionTreeToolkit;

​

public class Program

{

    static Dictionary<Expression, String> expressions;

    public static void Main()

    {

        expressions = new Dictionary<Expression, string>(ExpressionEqualityComparer.Default);

​

        Console.WriteLine("Expression equality:");

        Expression<Func<int, int, int>> sumXYExpression = (x, y) => x + y;

        Expression<Func<int, int, int>> prodXYExpression = (x, y) => x * y;

        Expression<Func<int, int, int>> sumABExpression = (a, b) => a + b;

        Expression<Func<int, int, int>> diffABExpression = (a, b) => a - b;

        AddExpression(sumXYExpression, "x + y");

        AddExpression(prodXYExpression, "x * y");

        AddExpression(sumABExpression, "a + b");

        AddExpression(diffABExpression, "a - b");

        Console.WriteLine();

    }

​

    static void AddExpression(Expression exp, string name)

    {

        try

        {

            expressions.Add(exp, name);

            Console.WriteLine("Added {0}, Count = {1}, HashCode = {2}",

                name, expressions.Count.ToString(), exp.GetHashCode());

        }

        catch (ArgumentException)

        {

            Console.WriteLine("An expression equal to {0} is already in the collection.", name);

        }

    }

}

/* This example produces the following output:

 *

    Expression equality:

    Added x + y, Count = 1, HashCode = 9265398

    Added x * y, Count = 2, HashCode = 261086

    An expression equal to a + b is already in the collection.

    Added a - b, Count = 3, HashCode = 7571494

 *

*/

​