VectorForDefinition.cs

using System.Collections.Generic;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Abstraction.Sets;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Script.Operators.Conditional;
 
namespace Waher.Script.Operators.Vectors
{
    public class VectorForDefinition : QuaternaryOperator
    {
        private readonly string variableName;
 
        public VectorForDefinition(For Elements, int Start, int Length, Expression Expression)
            : base(Elements.LeftOperand, Elements.MiddleOperand, Elements.Middle2Operand, Elements.RightOperand, Start, Length, Expression)
        {
            this.variableName = Elements.VariableName;
        }
 
        public string VariableName => this.variableName;
 
        public override IElement Evaluate(Variables Variables)
        {
            if (!(this.left.Evaluate(Variables) is ICommutativeRingWithIdentityElement From))
                throw new ScriptRuntimeException("Invalid range.", this);
 
            if (!(this.middle.Evaluate(Variables) is ICommutativeRingWithIdentityElement To))
                throw new ScriptRuntimeException("Invalid range.", this);
 
            if (!(From.AssociatedSet is IOrderedSet S))
                throw new ScriptRuntimeException("Cannot compare range.", this);
 
            IElement Step;
            int Direction = S.Compare(From, To);
            bool Done;
 
            if (!(this.middle2 is null))
            {
                Step = this.middle2.Evaluate(Variables);
 
                if (Direction < 0)
                {
                    if (S.Compare(Step, From.Zero) <= 0)
                        throw new ScriptRuntimeException("Invalid step size for corresponding range.", this);
                }
                else if (Direction > 0)
                {
                    if (S.Compare(Step, From.Zero) >= 0)
                        throw new ScriptRuntimeException("Invalid step size for corresponding range.", this);
                }
            }
            else
            {
                if (Direction <= 0)
                    Step = From.One;
                else
                    Step = From.One.Negate();
            }
 
            LinkedList<IElement> Elements = new LinkedList<IElement>();
 
            do
            {
                Variables[this.variableName] = From;
                Elements.AddLast(this.right.Evaluate(Variables));
 
                if (Direction == 0)
                    Done = true;
                else
                {
                    From = Arithmetics.Add.EvaluateAddition(From, Step, this) as ICommutativeRingWithIdentityElement;
                    if (From is null)
                        throw new ScriptRuntimeException("Invalid step size.", this);
 
                    if (Direction > 0)
                        Done = S.Compare(From, To) < 0;
                    else
                        Done = S.Compare(From, To) > 0;
                }
            }
            while (!Done);
 
            return this.Encapsulate(Elements);
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            if (!this.isAsync)
                return this.Evaluate(Variables);
 
            if (!(await this.left.EvaluateAsync(Variables) is ICommutativeRingWithIdentityElement From))
                throw new ScriptRuntimeException("Invalid range.", this);
 
            if (!(await this.middle.EvaluateAsync(Variables) is ICommutativeRingWithIdentityElement To))
                throw new ScriptRuntimeException("Invalid range.", this);
 
            if (!(From.AssociatedSet is IOrderedSet S))
                throw new ScriptRuntimeException("Cannot compare range.", this);
 
            IElement Step;
            int Direction = S.Compare(From, To);
            bool Done;
 
            if (!(this.middle2 is null))
            {
                Step = await this.middle2.EvaluateAsync(Variables);
 
                if (Direction < 0)
                {
                    if (S.Compare(Step, From.Zero) <= 0)
                        throw new ScriptRuntimeException("Invalid step size for corresponding range.", this);
                }
                else if (Direction > 0)
                {
                    if (S.Compare(Step, From.Zero) >= 0)
                        throw new ScriptRuntimeException("Invalid step size for corresponding range.", this);
                }
            }
            else
            {
                if (Direction <= 0)
                    Step = From.One;
                else
                    Step = From.One.Negate();
            }
 
            LinkedList<IElement> Elements = new LinkedList<IElement>();
 
            do
            {
                Variables[this.variableName] = From;
                Elements.AddLast(await this.right.EvaluateAsync(Variables));
 
                if (Direction == 0)
                    Done = true;
                else
                {
                    From = Arithmetics.Add.EvaluateAddition(From, Step, this) as ICommutativeRingWithIdentityElement;
                    if (From is null)
                        throw new ScriptRuntimeException("Invalid step size.", this);
 
                    if (Direction > 0)
                        Done = S.Compare(From, To) < 0;
                    else
                        Done = S.Compare(From, To) > 0;
                }
            }
            while (!Done);
 
            return this.Encapsulate(Elements);
        }
 
        protected virtual IElement Encapsulate(LinkedList<IElement> Elements)
        {
            return VectorDefinition.Encapsulate(Elements, true, this);
        }
 
    }
}