Upsilon/Upsilon/BaseTypes/ScriptString.cs

using System;
using Upsilon.BaseTypes.Number;
using Upsilon.BaseTypes.ScriptTypeInterfaces;
using Upsilon.Evaluator;
using Upsilon.Text;

namespace Upsilon.BaseTypes
{
    internal class ScriptString : ScriptType, IIndexable, ILengthType
    {
        public ScriptString(string value)
        {
            Value = value;
        }

        public string Value { get; }
        public override TypeContainer Type => BaseTypes.Type.String;
        public override object ToCSharpObject()
        {
            return Value;
        }

        public override System.Type GetCSharpType()
        {
            return typeof(string);
        }

        public override bool Equals(object obj)
        {
            if (obj == null)
                return false;
            if (obj is string str)
            {
                return string.Equals(str, Value);
            }
            if (!(obj is ScriptString s))
                return false;
            return Equals(s);
        }

        public override int GetHashCode()
        {
            return (Value != null ? Value.GetHashCode() : 0);
        }

        public static implicit operator string(ScriptString s)
        {
            return s.Value;
        }

        private bool Equals(ScriptString s)
        {
            return s != null && string.Equals(s.Value, Value);
        }

        public static ScriptString operator +(ScriptString a, ScriptType b)
        {
            switch (b)
            {
                case ScriptString s:
                    return a + s;
                case ScriptBoolean bl:
                    return a + bl;
                case ScriptNumberLong l:
                    return a + l;
                case ScriptNumberDouble d:
                    return a + d;
            }
            throw new ArgumentException($"Adding Type '{b.Type}' to a LuaString is not supported.");
        }

        public static ScriptString operator +(ScriptString a, ScriptString b)
        {
            return new ScriptString(a.Value + b.Value);
        }

        public static ScriptString operator +(ScriptString a, ScriptBoolean b)
        {
            return new ScriptString(a.Value + b.Value);
        }

        public static ScriptString operator +(ScriptString a, ScriptNumberLong b)
        {
            return new ScriptString(a.Value + b.Value);
        }

        public static ScriptString operator +(ScriptString a, ScriptNumberDouble b)
        {
            return new ScriptString(a.Value + b.Value);
        }

        public override string ToString()
        {
            return Value;
        }

        public ScriptNumberLong Length()
        {
            return new ScriptNumberLong(Value.Length);
        }

        public ScriptType Get(Diagnostics diagnostics, TextSpan span, ScriptType index, EvaluationScope scope)
        {
            int i;
            if (index.Type == BaseTypes.Type.String)
            {
                var str = (ScriptString)index;
                i = int.Parse(str.Value);
            }
            else if (index.Type == BaseTypes.Type.Number)
            {
                var ind = (Number.ScriptNumberLong) index;
                i = (int) ind.Value;
            }
            else
            {
                return null;
            }
            return new ScriptString(Value[i - 1].ToString());
        }

        public void Set(Diagnostics diagnostics, TextSpan span, ScriptType index, ScriptType value)
        {
            throw new NotSupportedException();
        }
    }
}