Citadel-Station-13-RP/code/modules/scripting/Interpreter/Evaluation.dm

/proc/isobject(x)
	return (istype(x, /datum) || istype(x, /list) || istype(x, /savefile) || istype(x, /client) || (x==world))

/n_Interpreter
	proc
		Eval(node/expression/exp)
			if(istype(exp, /node/expression/FunctionCall))
				return RunFunction(exp)
			else if(istype(exp, /node/expression/operator))
				return EvalOperator(exp)
			else if(istype(exp, /node/expression/value/literal))
				var/node/expression/value/literal/lit=exp
				return lit.value
			else if(istype(exp, /node/expression/value/reference))
				var/node/expression/value/reference/ref=exp
				return ref.value
			else if(istype(exp, /node/expression/value/variable))
				var/node/expression/value/variable/v=exp
				if(!v.object)
					return Eval(GetVariable(v.id.id_name))
				else
					var/datum/D
					if(istype(v.object, /node/identifier))
						D=GetVariable(v.object:id_name)
					else
						D=v.object
					D=Eval(D)
					if(!isobject(D))
						return null
					if(!D.vars.Find(v.id.id_name))
						RaiseError(new/runtimeError/UndefinedVariable("[v.object.ToString()].[v.id.id_name]"))
						return null
					return Eval(D.vars[v.id.id_name])
			else if(istype(exp, /node/expression))
				RaiseError(new/runtimeError/UnknownInstruction())
			else
				return exp

		EvalOperator(node/expression/operator/exp)
			if(istype(exp, /node/expression/operator/binary))
				var/node/expression/operator/binary/bin=exp
				switch(bin.type)
					if(/node/expression/operator/binary/Equal)
						return Equal(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/NotEqual)
						return NotEqual(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Greater)
						return Greater(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Less)
						return Less(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/GreaterOrEqual)
						return GreaterOrEqual(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/LessOrEqual)
						return LessOrEqual(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/LogicalAnd)
						return LogicalAnd(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/LogicalOr)
						return LogicalOr(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/LogicalXor)
						return LogicalXor(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/BitwiseAnd)
						return BitwiseAnd(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/BitwiseOr)
						return BitwiseOr(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/BitwiseXor)
						return BitwiseXor(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Add)
						return Add(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Subtract)
						return Subtract(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Multiply)
						return Multiply(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Divide)
						return Divide(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Power)
						return Power(Eval(bin.exp), Eval(bin.exp2))
					if(/node/expression/operator/binary/Modulo)
						return Modulo(Eval(bin.exp), Eval(bin.exp2))
					else
						RaiseError(new/runtimeError/UnknownInstruction())
			else
				switch(exp.type)
					if(/node/expression/operator/unary/Minus)
						return Minus(Eval(exp.exp))
					if(/node/expression/operator/unary/LogicalNot)
						return LogicalNot(Eval(exp.exp))
					if(/node/expression/operator/unary/BitwiseNot)
						return BitwiseNot(Eval(exp.exp))
					if(/node/expression/operator/unary/group)
						return Eval(exp.exp)
					else
						RaiseError(new/runtimeError/UnknownInstruction())


	//Binary//
		//Comparison operators
		Equal(a, b) 				return a==b
		NotEqual(a, b)			return a!=b //LogicalNot(Equal(a, b))
		Greater(a, b)				return a>b
		Less(a, b)					return a<b
		GreaterOrEqual(a, b)return a>=b
		LessOrEqual(a, b)		return a<=b
		//Logical Operators
		LogicalAnd(a, b)		return a&&b
		LogicalOr(a, b)			return a||b
		LogicalXor(a, b)		return (a||b) && !(a&&b)
		//Bitwise Operators
		BitwiseAnd(a, b)		return a&b
		BitwiseOr(a, b)			return a|b
		BitwiseXor(a, b)		return a^b
		//Arithmetic Operators
		Add(a, b)
			if(istext(a)&&!istext(b)) 		 b="[b]"
			else if(istext(b)&&!istext(a)) a="[a]"
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("+", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("+", a, b))
				return null
			return a+b
		Subtract(a, b)
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("-", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("-", a, b))
				return null
			return a-b
		Divide(a, b)
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("/", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("/", a, b))
				return null
			if(b==0)
				RaiseError(new/runtimeError/DivisionByZero())
				return null
			return a/b
		Multiply(a, b)
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("*", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("*", a, b))
				return null
			return a*b
		Modulo(a, b)
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("%", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("%", a, b))
				return null
			return a%b
		Power(a, b)
			if(isobject(a) && !isobject(b))
				RaiseError(new/runtimeError/TypeMismatch("**", a, b))
				return null
			else if(isobject(b) && !isobject(a))
				RaiseError(new/runtimeError/TypeMismatch("**", a, b))
				return null
			return a**b

	//Unary//
		Minus(a)						return -a
		LogicalNot(a)				return !a
		BitwiseNot(a)				return ~a