using System;
using System.Linq.Expressions;

public class Test
{
	
	
    public static Expression<Func<T, bool>> Or<T>(
    	Expression<Func<T, bool>> source, Expression<Func<T, bool>> expression
    ) {
        if (source == null)
            return expression;
        var p = Expression.Parameter(typeof(T));
        return (Expression<Func<T,bool>>)Expression.Lambda(
        	Expression.Or(
        		Expression.Invoke(source, p)
        	,   Expression.Invoke(expression, p)
        	)
        ,   p
        );
    }	
	
	public static void Main()
	{
		Expression<Func<int,bool>> a = x=>x > 5;
		Expression<Func<int,bool>> b = x=>x < -5;
		var or = Or(a, b);
		var f = (Func<int,bool>)or.Compile();
		for (int i = -10 ; i <= 10 ; i++) {
			Console.WriteLine("{0} - {1}", i, f(i));
		}
	}
}