chibi-scheme/lib/srfi/9.scm
Alex Shinn 8b5eb68238 File descriptors maintain a reference count of ports open on them
They can be close()d explicitly with close-file-descriptor, and
will close() on gc, but only explicitly closing the last port on
them will close the fileno.  Notably needed for network sockets
where we open separate input and output ports on the same socket.
2014-02-20 22:32:50 +09:00

72 lines
3 KiB
Scheme

(define-syntax define-record-type
(er-macro-transformer
(lambda (expr rename compare)
(let* ((name+parent (cadr expr))
(name (if (pair? name+parent) (car name+parent) name+parent))
(parent (and (pair? name+parent) (cadr name+parent)))
(name-str (symbol->string (identifier->symbol name)))
(procs (cddr expr))
(make (caar procs))
(make-fields (cdar procs))
(pred (cadr procs))
(fields (cddr procs))
(_define (rename 'define))
(_lambda (rename 'lambda))
(_let (rename 'let))
(_register (rename 'register-simple-type))
(_slot-set! (rename 'slot-set!))
(_type_slot_offset (rename 'type-slot-offset)))
;; catch a common mistake
(if (eq? name make)
(error "same binding for record rtd and constructor" name))
`(,(rename 'begin)
;; type
(,_define ,name (,_register ,name-str ,parent ',(map car fields)))
;; predicate
(,_define ,pred (,(rename 'make-type-predicate)
,(symbol->string (identifier->symbol pred))
,name))
;; fields
,@(map (lambda (f)
(and (pair? f) (pair? (cdr f))
`(,_define ,(cadr f)
(,(rename 'make-getter)
,(symbol->string
(identifier->symbol (cadr f)))
,name
(,_type_slot_offset ,name ',(car f))))))
fields)
,@(map (lambda (f)
(and (pair? f) (pair? (cdr f)) (pair? (cddr f))
`(,_define ,(car (cddr f))
(,(rename 'make-setter)
,(symbol->string
(identifier->symbol (car (cddr f))))
,name
(,_type_slot_offset ,name ',(car f))))))
fields)
;; constructor
(,_define ,make
,(let lp ((ls make-fields) (sets '()))
(cond
((null? ls)
`(,_let ((%make (,(rename 'make-constructor)
,(symbol->string (identifier->symbol make))
,name)))
(,_lambda ,make-fields
(,_let ((res (%make)))
,@sets
res))))
(else
(let ((field (assq (car ls) fields)))
(cond
((not field)
(error "unknown record field in constructor" (car ls)))
((pair? (cddr field))
(lp (cdr ls)
(cons `(,(car (cddr field)) res ,(car ls)) sets)))
(else
(lp (cdr ls)
(cons `(,_slot-set! ,name res (,_type_slot_offset ,name ',(car ls)) ,(car ls))
sets))))))))))))))