DropCollection.cs

using System;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Persistence.SQL
{
    public class DropCollection : ScriptNode, IEvaluateAsync
    {
        private SourceDefinition source;
 
        public DropCollection(SourceDefinition Source, int Start, int Length, Expression Expression)
            : base(Start, Length, Expression)
        {
            this.source = Source;
            this.source?.SetParent(this);
        }
 
        public override bool IsAsynchronous => true;
 
        public override IElement Evaluate(Variables Variables)
        {
            return this.EvaluateAsync(Variables).Result;
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            IDataSource Source = await this.source.GetSource(Variables);
            await Source.DropCollection();
            return ObjectValue.Null;
        }
 
        public override bool ForAllChildNodes(ScriptNodeEventHandler Callback, object State, SearchMethod Order)
        {
            if (Order == SearchMethod.DepthFirst)
            {
                if (!(this.source?.ForAllChildNodes(Callback, State, Order) ?? true))
                    return false;
            }
 
            bool b;
 
            if (!(this.source is null))
            {
                b = !Callback(this.source, out ScriptNode NewNode, State);
                if (!(NewNode is null) && NewNode is SourceDefinition Source2)
                {
                    this.source = Source2;
                    this.source.SetParent(this);
                }
 
                if (b || (Order == SearchMethod.TreeOrder && !this.source.ForAllChildNodes(Callback, State, Order)))
                    return false;
            }
 
            if (Order == SearchMethod.BreadthFirst)
            {
                if (!(this.source?.ForAllChildNodes(Callback, State, Order) ?? true))
                    return false;
            }
 
            return true;
        }
 
        public override bool Equals(object obj)
        {
            return (obj is DropCollection O &&
                AreEqual(this.source, O.source) &&
                base.Equals(obj));
        }
 
        public override int GetHashCode()
        {
            int Result = base.GetHashCode();
            Result ^= Result << 5 ^ GetHashCode(this.source);
            return Result;
        }
 
    }
}