SubtractFromSelf.cs

using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
 
namespace Waher.Script.Operators.Assignments.WithSelf
{
    public class SubtractFromSelf : Assignment
    {
        public SubtractFromSelf(string VariableName, ScriptNode Operand, int Start, int Length, Expression Expression)
            : base(VariableName, Operand, Start, Length, Expression)
        {
        }
 
        public override IElement Evaluate(Variables Variables)
        {
            if (!Variables.TryGetVariable(this.VariableName, out Variable v))
                throw new ScriptRuntimeException("Variable not found.", this);
 
            IElement E = this.op.Evaluate(Variables);
            E = Arithmetics.Subtract.EvaluateSubtraction(v.ValueElement, E, this);
 
            Variables[this.VariableName] = E;
 
            return E;
        }
 
        public override async Task<IElement> EvaluateAsync(Variables Variables)
        {
            if (!Variables.TryGetVariable(this.VariableName, out Variable v))
                throw new ScriptRuntimeException("Variable not found.", this);
 
            IElement E = await this.op.EvaluateAsync(Variables);
            E = Arithmetics.Subtract.EvaluateSubtraction(v.ValueElement, E, this);
 
            Variables[this.VariableName] = E;
 
            return E;
        }
    }
}