GroupObject.cs

using System;
using System.Collections.Generic;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
 
namespace Waher.Script.Persistence.SQL.Groups
{
    public class GroupObject
    {
        private readonly IElement[] aggregates;
        private readonly Variables variables;
        private readonly Dictionary<string, object> groupedValues = new Dictionary<string, object>();
        private readonly int groupCount;
 
        public GroupObject(object[] GroupByValues, IElement[] Aggregates,
            ScriptNode[] GroupNames, Variables Variables)
        {
            this.variables = Variables;
            this.aggregates = Aggregates;
 
            int i;
 
            this.groupCount = GroupNames.Length;
            if (GroupByValues.Length != this.groupCount)
                throw new ArgumentException("Length mismatch.", nameof(GroupByValues));
 
            string Name;
            ScriptNode Node;
            IElement E;
 
            for (i = 0; i < this.groupCount; i++)
            {
                Node = GroupNames[i];
                if (Node is null)
                    continue;
 
                if (Node is VariableReference Ref)
                    Name = Ref.VariableName;
                else
                {
                    E = Node.Evaluate(Variables);   // TODO: Async
                    Name = ScriptNode.ToString(E);
                }
 
                if (!string.IsNullOrEmpty(Name))
                    this.groupedValues[Name] = GroupByValues[i];
            }
        }
 
        public object this[string Name]
        {
            get
            {
                if (this.groupedValues.TryGetValue(Name, out object Value))
                    return Value;
                else if (this.variables.TryGetVariable(Name, out Variable v))
                    return v.ValueObject;
                else
                    return null;
            }
 
            set
            {
                this.groupedValues[Name] = value;
            }
        }
 
        public IElement[] Aggregates => this.aggregates;
    }
}