Deserialize.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using Waher.Persistence;
using Waher.Persistence.NeuroLedger;
using Waher.Persistence.Serialization;
using Waher.Script;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Script.Objects.VectorSpaces;
 
namespace Waher.Service.NeuroLedger.Functions
{
    public class Deserialize : FunctionMultiVariate
    {
        public Deserialize(ScriptNode Argument, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Argument }, new ArgumentType[] { ArgumentType.Normal }, Start, Length, Expression)
        {
        }
 
        public Deserialize(ScriptNode Argument, ScriptNode BaseType, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Argument, BaseType }, new ArgumentType[] { ArgumentType.Normal, ArgumentType.Scalar }, 
                  Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(Deserialize);
 
        public override string[] Aliases => new string[] { "FromBinary" };
 
        public override string[] DefaultArgumentNames => new string[] { "ByteArray", "BaseType" };
 
        protected virtual IDeserializer GetDeserializer(Variables Variables, byte[] Data)
        {
            return new BinaryDeserializer(string.Empty, Encoding.UTF8, Data, 1);
        }
 
        public override bool IsAsynchronous => true;
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            return this.EvaluateAsync(Arguments, Variables).Result;
        }
 
        public override async Task<IElement> EvaluateAsync(IElement[] Arguments, Variables Variables)
        {
            if (!(Arguments[0].AssociatedObjectValue is byte[] Bin))
                throw new ScriptRuntimeException("The first argument to the Deserialize function must be a byte array.", this);
 
            Type BaseType;
 
            if (Arguments.Length < 2)
                BaseType = typeof(object);
            else if (Arguments[1].AssociatedObjectValue is Type TypeValue)
                BaseType = TypeValue;
            else
                throw new ScriptRuntimeException("The optional second argument to the Deserialize function must be a type value.", this);
 
            if (!(Ledger.Provider is NeuroLedgerProvider Provider))
                throw new ScriptRuntimeException("Neuro-Ledger not initialized properly.", this);
 
            IDeserializer Reader = this.GetDeserializer(Variables, Bin);
            IObjectSerializer Serializer = await Provider.GetObjectSerializer(BaseType);
            bool First = true;
            object Result = null;
            List<object> List = null;
 
            while (Reader.ReadBit())
            {
                if (First)
                    First = false;
                else if (List is null)
                    List = new List<object>() { Result };
 
                Result = await Serializer.Deserialize(Reader, null, false);
                List?.Add(Result);
            }
 
            if (List is null)
                return new ObjectValue(Result);
            else
                return new ObjectVector(List.ToArray());
        }
 
    }
}