Extends the System.Linq.Dynamic.ExpressionParser sample to build a generic expression parser.

FunctionFactory.cs

    public static class FunctionFactory
    {
        private static Delegate CreateInternal(Type[] argumentTypes, Type returnType, string expression, string[] argumentNames = null)
        {
            if (argumentNames != null)
            {
                if (argumentTypes.Length != argumentNames.Length)
                    throw new ArgumentException("The number of argument names does not equal the number of argument types.");
            }

            var @params = argumentTypes.Select(
                (t, i) => Expression.Parameter(t, argumentNames[i])).ToArray();
            ExpressionParser parser = new ExpressionParser(@params, expression, null);

            var @delegate = Expression.Lambda(parser.Parse(returnType), @params).Compile();
            return @delegate;
        }

        public static Func<TReturn> Create<TReturn>(string expression, string[] argumentNames = null)
        {
            return (Func<TReturn>)CreateInternal(new Type[0], typeof(TReturn), expression, argumentNames);
        }

        public static Func<A, TReturn> Create<A, TReturn>(string expression, string[] argumentNames = null)
        {
            return (Func<A, TReturn>)CreateInternal(new[] { typeof(A) }, typeof(TReturn), expression, argumentNames);
        }

        public static Func<A, B, TReturn> Create<A, B, TReturn>(string expression, string[] argumentNames = null)
        {
            return (Func<A, B, TReturn>)CreateInternal(new[] { typeof(A), typeof(B) }, typeof(TReturn), expression, argumentNames);
        }
    }