SetUnit.cs

using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Script.Units;
 
namespace Waher.Script.Operators
{
    public class SetUnit : UnaryScalarOperator
    {
        private readonly Unit unit;
 
        public SetUnit(ScriptNode Operand, Unit Unit, int Start, int Length, Expression Expression)
            : base(Operand, Start, Length, Expression)
        {
            this.unit = Unit;
        }
 
        public Unit Unit => this.unit;
 
        public override IElement EvaluateScalar(IElement Operand, Variables Variables)
        {
            if (Operand.AssociatedObjectValue is double D)
                return new PhysicalQuantity(D, this.unit);
 
            if (Operand is Measurement M)
            {
                if (Unit.TryConvert(M.Magnitude, M.Unit, this.unit, out double Magnitude) &&
                    Unit.TryConvert(M.Error, M.Unit, this.unit, out double Error))
                {
                    return new Measurement(Magnitude, this.unit, Error);
                }
                else
                    throw new ScriptRuntimeException("Unable to convert from " + M.Unit.ToString() + " to " + this.unit.ToString() + ".", this);
            }
 
            if (Operand.AssociatedObjectValue is IPhysicalQuantity PQ)
            {
                PhysicalQuantity Q = PQ.ToPhysicalQuantity();
                if (Unit.TryConvert(Q.Magnitude, Q.Unit, this.unit, out double Magnitude))
                    return new PhysicalQuantity(Magnitude, this.unit);
                else
                    throw new ScriptRuntimeException("Unable to convert from " + Q.Unit.ToString() + " to " + this.unit.ToString() + ".", this);
            }
 
            throw new ScriptRuntimeException("Unable to set physical unit.", this);
        }
    }
}