Integer.cs

using System;
using System.Collections.Generic;
using System.Numerics;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Functions.Scalar
{
    public class Integer : FunctionOneScalarVariable
    {
        public Integer(ScriptNode Argument, int Start, int Length, Expression Expression)
            : base(Argument, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(Integer);
 
        public override string[] Aliases
        {
            get { return new string[] { "int" }; }
        }
 
        public override IElement EvaluateScalar(double Argument, Variables Variables)
        {
            return new DoubleNumber(Math.Truncate(Argument));
        }
 
        public override IElement EvaluateScalar(bool Argument, Variables Variables)
        {
            return new DoubleNumber(Argument ? 1 : 0);
        }
 
        public override IElement EvaluateScalar(string Argument, Variables Variables)
        {
            if (!Expression.TryParse(Argument, out double d))
                throw new ScriptException("Not an integer.");
 
            return new DoubleNumber(Math.Truncate(d));
        }
 
        public override IElement EvaluateScalar(IElement Argument, Variables Variables)
        {
            return this.EvaluateScalar(Argument.ToString(), Variables);
        }
 
        public override Task<IElement> EvaluateScalarAsync(IElement Argument, Variables Variables)
        {
            return Task.FromResult(this.EvaluateScalar(Argument, Variables));
        }
 
        public override PatternMatchResult PatternMatch(IElement CheckAgainst, Dictionary<string, IElement> AlreadyFound)
        {
            object Obj = CheckAgainst.AssociatedObjectValue;
            
            if (!(Obj is BigInteger))
            {
                if (Obj is double d)
                {
                    if (Math.Truncate(d) != d)
                        return PatternMatchResult.NoMatch;
                }
                else if (Obj is string s)
                {
                    if (int.TryParse(s, out int i))
                        return this.Argument.PatternMatch(new DoubleNumber(i), AlreadyFound);
                    else if (long.TryParse(s, out long l) && ((long)((double)l)) == l)
                        return this.Argument.PatternMatch(new DoubleNumber(l), AlreadyFound);
                    else if (BigInteger.TryParse(s, out BigInteger I))
                        return this.Argument.PatternMatch(new Objects.Integer(I), AlreadyFound);
                }
                else
                    return PatternMatchResult.NoMatch;
            }
 
            return this.Argument.PatternMatch(CheckAgainst, AlreadyFound);
        }
    }
}