GetHashObject.cs

using System.Threading.Tasks;
using Waher.Runtime.HashStore;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Persistence.Functions
{
    public class GetHashObject : FunctionMultiVariate
    {
        public GetHashObject(ScriptNode Hash, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Hash }, argumentTypes1Normal, Start, Length, Expression)
        {
        }
 
        public GetHashObject(ScriptNode Realm, ScriptNode Hash, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Realm, Hash },
                  new ArgumentType[] { ArgumentType.Scalar, ArgumentType.Normal },
                  Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(GetHashObject);
 
        public override string[] DefaultArgumentNames => new string[] { "Realm", "Hash" };
 
        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)
        {
            int c = Arguments.Length;
            object Result;
 
            if (!(Arguments[c - 1].AssociatedObjectValue is byte[] Hash))
                throw new ScriptRuntimeException("Expected last argument to be a hash digest.", this);
 
            if (Arguments.Length > 1)
            {
                if (!(Arguments[0].AssociatedObjectValue is string Realm))
                    throw new ScriptRuntimeException("Expected first argument to be string.", this);
 
                Result = await PersistedHashes.TryGetAssociatedObject(Realm, Hash);
            }
            else
                Result = await PersistedHashes.TryGetAssociatedObject(Hash);
 
            return new ObjectValue(Result);
        }
    }
}