Concat.cs

using System.Text;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Functions.Strings
{
    public class Concat : FunctionMultiVariate, IIterativeEvaluation
    {
        public Concat(ScriptNode Vector, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Vector }, new ArgumentType[] { ArgumentType.Vector }, Start, Length, Expression)
        {
        }
 
        public Concat(ScriptNode Vector, ScriptNode Delimiter, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Vector, Delimiter }, new ArgumentType[] { ArgumentType.Vector, ArgumentType.Scalar }, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(Concat);
 
        public override string[] DefaultArgumentNames => new string[] { "Vector", "Delimiter" };
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            if (!(Arguments[0] is IVector Vector))
                return Arguments[0];
 
            string Delimiter = Arguments.Length > 1 ? ToString(Arguments[1]) : null;
 
            StringBuilder Result = new StringBuilder();
            bool First = true;
 
            foreach (IElement Item in Vector.VectorElements)
            {
                if (!(Item.AssociatedObjectValue is string s))
                    s = ToString(Item) ?? string.Empty;
 
                if (First)
                    First = false;
                else if (!(Delimiter is null))
                    Result.Append(Delimiter);
 
                Result.Append(s);
            }
 
            return new StringValue(Result.ToString());
        }
 
        #region IIterativeEvalaution
 
        public bool CanEvaluateIteratively => this.Arguments.Length == 1 ||
            (this.Arguments.Length == 2 && this.Arguments[1] is ConstantElement);
 
        public IIterativeEvaluator CreateEvaluator()
        {
            return new ConcatEvaluator(this);
        }
 
        #endregion
    }
}