NTERA/NTERA.Interpreter/Value.cs

using System;
using NTERA.Interpreter.Compiler;

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 static Value operator +(Value value1, Value value2)
		{
			return value1.Operate(value2, Token.Plus);
		}

		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);
		}
	}
}