Properties.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Waher.Runtime.Inventory;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Functions.Runtime.PropertyEnumerators;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Functions.Runtime
{
    public class Properties : FunctionOneVariable
    {
        public Properties(ScriptNode Argument, int Start, int Length, Expression Expression)
            : base(Argument, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(Properties);
 
        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 E = await this.Argument.EvaluateAsync(Variables);
            object Obj = E.AssociatedObjectValue;
            if (Obj is null)
                return ObjectValue.Null;
 
            IPropertyEnumerator Enumerator = GetEnumerator(Obj.GetType());
 
            if (Enumerator is null)
                return ObjectValue.Null;
            else
                return await Enumerator.EnumerateProperties(Obj);
        }
 
        private static readonly Dictionary<Type, IPropertyEnumerator> enumerators = new Dictionary<Type, IPropertyEnumerator>();
 
        private static IPropertyEnumerator GetEnumerator(Type T)
        {
            lock (enumerators)
            {
                if (enumerators.TryGetValue(T, out IPropertyEnumerator Enumerator))
                    return Enumerator;
            }
 
            IPropertyEnumerator Best = Types.FindBest<IPropertyEnumerator, Type>(T);
            
            lock (enumerators)
            {
                enumerators[T] = Best;
            }
 
            return Best;
        }
 
        public override IElement Evaluate(IElement Argument, Variables Variables)
        {
            return ObjectValue.Null;
        }
    }
}