NTERA/NTERA.Interpreter/Value.cs

using System;

namespace NTERA.Interpreter
{
    public enum ValueType
    {
        Real,
        String
    }

    public struct Value
    {
        public ValueType Type { get; set; }

        public double Real { get; }
        public string String { get; }

        public Value(bool boolean) : this(boolean ? 1d : 0d)
        {

        }

        public Value(double real) : this()
        {
            Type = ValueType.Real;
            Real = real;
            String = real.ToString("N");
        }

        public Value(string str)
            : this()
        {
            Type = ValueType.String;
            String = str;
            Real = Double.NaN;
        }

        public Value Operate(Value b, Token tok)
        {
            Value a = this;

            bool isStringOperation = a.Type == ValueType.String || b.Type == ValueType.String;

            if (isStringOperation)
            {
                switch (tok)
                {
                    case Token.Plus: return new Value(a.String + b.String);
                    case Token.Equal: return new Value(a.String == b.String);
                    case Token.NotEqual: return new Value(a.String != b.String);
                }
            }
            else
            {
                switch (tok)
                {
                    case Token.Plus: return new Value(a.Real + b.Real);
                    case Token.Equal: return new Value(a.Real == b.Real);
                    case Token.NotEqual: return new Value(a.Real != b.Real);
                    case Token.Minus: return new Value(a.Real - b.Real);
                    case Token.Asterisk: return new Value(a.Real * b.Real);
                    case Token.Slash: return new Value(a.Real / b.Real);
                    case Token.Caret: return new Value(Math.Pow(a.Real, b.Real));
                    case Token.Less: return new Value(a.Real < b.Real ? 1 : 0);
                    case Token.More: return new Value(a.Real > b.Real ? 1 : 0);
                    case Token.LessEqual: return new Value(a.Real <= b.Real ? 1 : 0);
                    case Token.MoreEqual: return new Value(a.Real >= b.Real ? 1 : 0);
                }
            }

            throw new Exception($"Invalid operation on value ({tok}) on {(isStringOperation ? "string" : "double")}");
        }

        public override string ToString()
        {
            return String;
        }

        public static implicit operator double(Value value)
        {
            return value.Real;
        }

        public static implicit operator string(Value value)
        {
            return value.String;
        }

        public static implicit operator bool(Value value)
        {
            return value.Real != 0;
        }

        public static implicit operator Value(double value)
        {
            return new Value(value);
        }

        public static implicit operator Value(string value)
        {
            return new Value(value);
        }

        public static implicit operator Value(bool value)
        {
            return new Value(value);
        }
    }
}