PropertyOrder.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
 
namespace Waher.Script.Order
{
    public class PropertyOrder : IComparer<IElement>
    {
        private readonly ScriptNode node;
        private readonly string name;
        private readonly int sign;
        private Type lastType = null;
        private FieldInfo lastFieldInfo = null;
        private PropertyInfo lastPropertyInfo = null;
 
        public PropertyOrder(ScriptNode Node, string Name, int Sign)
        {
            this.node = Node;
            this.name = Name;
            this.sign = Sign;
        }
 
        public int Compare(IElement x, IElement y)
        {
            IElement v1 = this.GetValue(x);
            IElement v2 = this.GetValue(y);
 
            return this.sign * ElementOrder.Compare(v1, v2, this.node);
        }
 
        private IElement GetValue(IElement Obj)
        {
            object Value = Obj.AssociatedObjectValue;
            Type T = Value.GetType();
            if (T != this.lastType)
            {
                this.lastType = T;
 
                PropertyInfo PI = T.GetRuntimeProperty(this.name);
 
                if (!(PI is null))
                {
                    this.lastFieldInfo = null;
 
                    if (PI.CanRead && PI.GetMethod.IsPublic)
                        this.lastPropertyInfo = PI;
                    else
                        this.lastPropertyInfo = null;
                }
                else
                {
                    this.lastPropertyInfo = null;
 
                    FieldInfo FI = T.GetRuntimeField(this.name);
 
                    if (!(FI is null) && FI.IsPublic)
                        this.lastFieldInfo = FI;
                    else
                        this.lastFieldInfo = null;
                }
            }
 
            if (!(this.lastPropertyInfo is null))
                Value = ScriptNode.UnnestPossibleTaskSync(this.lastPropertyInfo.GetValue(Value));
            else if (!(this.lastFieldInfo is null))
                Value = ScriptNode.UnnestPossibleTaskSync(this.lastFieldInfo.GetValue(Value));
            else
                Value = null;
 
            return Expression.Encapsulate(Value);
        }
    }
}