FieldAggregatorEnumerator.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using Waher.Persistence.Serialization;
using Waher.Script.Model;
using Waher.Script.Persistence.SQL.Groups;
 
namespace Waher.Script.Persistence.SQL.Enumerators
{
    public class FieldAggregatorEnumerator : IResultSetEnumerator
    {
        private readonly KeyValuePair<string, ScriptNode>[] additionalFields;
        private readonly IResultSetEnumerator e;
        private readonly Variables variables;
        private ObjectProperties objectVariables = null;
        private object current = null;
 
        public FieldAggregatorEnumerator(IResultSetEnumerator ItemEnumerator, Variables Variables, KeyValuePair<string, ScriptNode>[] AdditionalFields)
        {
            this.e = ItemEnumerator;
            this.variables = Variables;
            this.additionalFields = AdditionalFields;
        }
 
        public object Current => this.current;
 
        public bool MoveNext()
        {
            return this.MoveNextAsync().Result;
        }
 
        public async Task<bool> MoveNextAsync()
        {
            if (!await this.e.MoveNextAsync())
                return false;
 
            this.current = this.e.Current;
 
            if (this.objectVariables is null)
                this.objectVariables = new ObjectProperties(this.current, this.variables);
            else
                this.objectVariables.Object = this.e.Current;
 
            if (this.current is GenericObject GenObj)
            {
                foreach (KeyValuePair<string, ScriptNode> P in this.additionalFields)
                    GenObj[P.Key] = P.Value.Evaluate(this.objectVariables);
            }
            else if (this.current is GroupObject GroupObj)
            {
                foreach (KeyValuePair<string, ScriptNode> P in this.additionalFields)
                    GroupObj[P.Key] = P.Value.Evaluate(this.objectVariables);
            }
            else
            {
                GroupObject Obj = new GroupObject(new object[] { this.current }, new object[0], new ScriptNode[0], this.objectVariables);
 
                foreach (KeyValuePair<string, ScriptNode> P in this.additionalFields)
                    Obj[P.Key] = P.Value.Evaluate(this.objectVariables);
 
                this.current = Obj;
            }
 
            return true;
        }
 
        public void Reset()
        {
            this.e.Reset();
            this.current = null;
        }
    }
}