DynamicMember.cs

using System.Collections.Generic;
using System.Threading.Tasks;
using Waher.Runtime.Collections;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
 
namespace Waher.Script.Operators.Membership
{
    public class DynamicMember : NullCheckBinaryOperator
    {
        public DynamicMember(ScriptNode Left, ScriptNode Right, bool NullCheck, int Start, int Length, Expression Expression)
            : base(Left, Right, NullCheck, Start, Length, Expression)
        {
            this.isAsync = true;
        }
 
        public override bool IsAsynchronous => true;
 
        public override IElement Evaluate(Variables Variables)
        {
            return this.EvaluateAsync(Variables).Result;
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            IElement Operand = this.left.Evaluate(Variables);
            if (this.nullCheck && Operand.AssociatedObjectValue is null)
                return Operand;
 
            IElement Name = this.right.Evaluate(Variables);
 
            return await EvaluateDynamicMember(Operand, Name, this.nullCheck, this);
        }
 
        public static async Task<IElement> EvaluateDynamicMember(IElement Operand, IElement Member, bool NullCheck, ScriptNode Node)
        {
            if (Member.IsScalar)
            {
                if (!(Member.AssociatedObjectValue is string s))
                    throw new ScriptRuntimeException("Member names must be strings.", Node);
 
                return await NamedMember.EvaluateDynamic(Operand, s, NullCheck, Node);
            }
            else
            {
                if (Operand.IsScalar)
                {
                    ChunkedList<IElement> Elements = new ChunkedList<IElement>();
 
                    foreach (IElement E in Member.ChildElements)
                        Elements.Add(await EvaluateDynamicMember(Operand, E, NullCheck, Node));
 
                    return Member.Encapsulate(Elements, Node);
                }
                else
                {
                    ICollection <IElement> OperandElements = Operand.ChildElements;
                    ICollection<IElement> MemberElements = Member.ChildElements;
 
                    if (OperandElements.Count == MemberElements.Count)
                    {
                        ChunkedList<IElement> Elements = new ChunkedList<IElement>();
                        IEnumerator<IElement> eOperand = OperandElements.GetEnumerator();
                        IEnumerator<IElement> eMember = MemberElements.GetEnumerator();
 
                        try
                        {
                            while (eOperand.MoveNext() && eMember.MoveNext())
                                Elements.Add(await EvaluateDynamicMember(eOperand.Current, eMember.Current, NullCheck, Node));
                        }
                        finally
                        {
                            eOperand.Dispose();
                            eMember.Dispose();
                        }
 
                        return Operand.Encapsulate(Elements, Node);
                    }
                    else
                    {
                        ChunkedList <IElement> OperandResult = new ChunkedList<IElement>();
 
                        foreach (IElement OperandChild in OperandElements)
                        {
                            ChunkedList<IElement> MemberResult = new ChunkedList<IElement>();
 
                            foreach (IElement MemberChild in MemberElements)
                                MemberResult.Add(await EvaluateDynamicMember (OperandChild, MemberChild, NullCheck, Node));
 
                            OperandResult.Add(Member.Encapsulate(MemberResult, Node));
                        }
 
                        return Operand.Encapsulate(OperandResult, Node);
                    }
                }
            }
        }
 
    }
}