enum.scm

(define-module (dns enum)
  :export (rr-types
           int->rr rr->int
           class-types
           int->class class->int
           rcode-types
           int->rcode rcode->int
           opcode-types
           int->opcode opcode->int))

(define (flip-cons c)
  (cons (cdr c) (car c)))

(define (make-mappings name table)
  (values
   (lambda (i)
     (cond ((assv i (map flip-cons table)) => cdr)
           ((integer? i) (inexact->exact i))
           (else (scm-error 'wrong-type-arg (format #f "int->~a" name)
                            "Unknown value ~s, expected known integer or one of ~a"
                            (list i (map car table)) (list (map car table))))))

   (lambda (value)
     (cond ((integer? value) (inexact->exact value))
           ((assv value table) => cdr)
           (else (scm-error 'wrong-type-arg (format #f "~a->int" name)
                            "Unknown value ~s"
                            (list value) #f)))  )))

;; All number are documented at
;; https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6

(define rr-types
  '(; 0 reserved
    (A     . 1)
    (NS    . 2)
    (MD    . 3)
    (MF    . 4)
    (CNAME . 5)
    (SOA   . 6)
    (MB    . 7)
    (MG    . 8)
    (MR    . 9)
    (NULL  . 10)
    (WKS   . 11)
    (PTR   . 12)
    (HINFO . 13)
    (MINFO . 14)
    (MX    . 15)
    (TXT   . 16)
    (RP    . 17)
    (AFSDB . 18)
    (X25   . 19)
    (ISDN  . 20)
    (RT    . 21)
    (NSAP  . 22)
    (NSAP-PTR . 23)
    (SIG   . 24)
    (KEY   . 25)
    (PX    . 26)
    (GPOS  . 27)
    (AAAA  . 28)
    (LOC   . 29)
    (NXT   . 30)
    (EID   . 30)
    (NIMLOC . 32)
    (SRV   . 33)
    (ATMA  . 34)
    (NAPTR . 35)
    (KX    . 36)