lexer

const (
	ItemEOF ItemType = iota
	ItemEOL
	ItemError
	ItemDecimal
	ItemHexadecimal
	ItemOctal
	ItemOperator

	ErrorExpectedNumber           string = "expected a number"
	ErrorExpectedOperator         string = "expected an operator"
	ErrorHexadecimalNoDigits      string = "hexadecimal has no digits"
	ErrorHexadecimalNeedsExponent string = "hexadecimal needs exponent"
	ErrorExponentNoDigits         string = "exponent has no digits"
	ErrorInvalidOctalDigit        string = "invalid octal digit"
	ErrorUnexpectedCharacter      string = "unexpected character"
)