Creating a simplified version of ConstraintExpression with Type=RelativeToParent

ToParentExtension.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace Playground.Helpers
{
    [ContentProperty(nameof(Value))]
    public class ToParentExtension : IMarkupExtension<Constraint>
    {
        public String Value { get; set; }

        public Constraint ProvideValue(IServiceProvider serviceProvider)
        {
            if (Value is null)
                return null;
            var values = Value.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            if (values.Length != 3)
                return null;
            // Removing white spaces
            for (int i = 0; i < values.Length; i++)
                values[i] = values[i].Trim();
            // Getting values to define Constraint
            var property = values[0];
            if (!double.TryParse(values[1], out double constant))
                return null;
            if (!double.TryParse(values[2], out double factor))
                return null;
            //
            var pi = typeof(RelativeLayout).GetProperties()
                .FirstOrDefault(a => a.Name == property.ToString() && a.CanRead);
            return Constraint.RelativeToParent(p => (double)pi.GetValue(p) * factor + constant);
        }

        object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)
        {
            return ProvideValue(serviceProvider);
        }
    }
}