WhileDo.cs

using System;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Operators.Conditional
{
    public class WhileDo : BinaryOperator
    {
        public WhileDo(ScriptNode Condition, ScriptNode Statement, int Start, int Length, Expression Expression)
            : base(Condition, Statement, Start, Length, Expression)
        {
        }
 
        public override IElement Evaluate(Variables Variables)
        {
            IElement Last = null;
            BooleanValue Condition;
 
            Condition = this.left.Evaluate(Variables) as BooleanValue;
            if (Condition is null)
                throw new ScriptRuntimeException("Condition must evaluate to a boolean value.", this);
 
            while (Condition.Value)
            {
                Last = this.right.Evaluate(Variables);
 
                Condition = this.left.Evaluate(Variables) as BooleanValue;
                if (Condition is null)
                    throw new ScriptRuntimeException("Condition must evaluate to a boolean value.", this);
            }
 
            if (Last is null)
                return ObjectValue.Null;
            else
                return Last;
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            if (!this.isAsync)
                return this.Evaluate(Variables);
 
            IElement Last = null;
            BooleanValue Condition;
 
            Condition = await this.left.EvaluateAsync(Variables) as BooleanValue;
            if (Condition is null)
                throw new ScriptRuntimeException("Condition must evaluate to a boolean value.", this);
 
            while (Condition.Value)
            {
                Last = await this.right.EvaluateAsync(Variables);
 
                Condition = await this.left.EvaluateAsync(Variables) as BooleanValue;
                if (Condition is null)
                    throw new ScriptRuntimeException("Condition must evaluate to a boolean value.", this);
            }
 
            if (Last is null)
                return ObjectValue.Null;
            else
                return Last;
        }
    }
}