IsEmpty.cs

using System.Numerics;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Functions.Strings
{
    public class IsEmpty : FunctionOneScalarVariable
    {
        public IsEmpty(ScriptNode Argument, int Start, int Length, Expression Expression)
            : base(Argument, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(IsEmpty);
 
        public override string[] Aliases
        {
            get { return new string[] { "empty" }; }
        }
 
        public override IElement EvaluateScalar(IElement Argument, Variables Variables)
        {
            object Value = Argument.AssociatedObjectValue;
 
            if (Value is null)
                return BooleanValue.True;
            else if (Value is string s)
                return this.EvaluateScalar(s, Variables);
            else
                return this.EvaluateScalar(Value.ToString(), Variables);
        }
 
        public override Task<IElement> EvaluateScalarAsync(IElement Argument, Variables Variables)
        {
            return Task.FromResult(this.EvaluateScalar(Argument, Variables));
        }
 
        public override IElement EvaluateScalar(string Argument, Variables Variables)
        {
            if (string.IsNullOrEmpty(Argument))
                return BooleanValue.True;
            else
                return BooleanValue.False;
        }
 
        public override IElement EvaluateScalar(bool Argument, Variables Variables)
        {
            return BooleanValue.False;
        }
 
        public override IElement EvaluateScalar(double Argument, Variables Variables)
        {
            return BooleanValue.False;
        }
 
        public override IElement EvaluateScalar(Complex Argument, Variables Variables)
        {
            return BooleanValue.False;
        }
 
        public override IElement EvaluateScalar(PhysicalQuantity Argument, Variables Variables)
        {
            return BooleanValue.False;
        }
 
        public override IElement EvaluateScalar(Measurement Argument, Variables Variables)
        {
            return BooleanValue.False;
        }
    }
}