home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Dream 44
/
Amiga_Dream_44.iso
/
RiscPc
/
programmation
/
scm4e2.arc
/
!Scm
/
slib
/
structure
< prev
next >
Wrap
Text File
|
1994-05-25
|
3KB
|
69 lines
;;; "structure.scm" syntax-case structure macros
;;; Written by Robert Hieb & Kent Dybvig
;;; This file was munged by a simple minded sed script since it left
;;; its original authors' hands. See syncase.sh for the horrid details.
;;; structure.ss
;;; Robert Hieb & Kent Dybvig
;;; 92/06/18
(define-syntax define-structure
(lambda (x)
(define construct-name
(lambda (template-identifier . args)
(implicit-identifier
template-identifier
(string->symbol
(apply string-append
(map (lambda (x)
(if (string? x)
x
(symbol->string (syntax-object->datum x))))
args))))))
(syntax-case x ()
((_ (name id1 ...))
(syntax (define-structure (name id1 ...) ())))
((_ (name id1 ...) ((id2 init) ...))
(with-syntax
((constructor (construct-name (syntax name) "make-" (syntax name)))
(predicate (construct-name (syntax name) (syntax name) "?"))
((access ...)
(map (lambda (x) (construct-name x (syntax name) "-" x))
(syntax (id1 ... id2 ...))))
((assign ...)
(map (lambda (x)
(construct-name x "set-" (syntax name) "-" x "!"))
(syntax (id1 ... id2 ...))))
(structure-length
(+ (length (syntax (id1 ... id2 ...))) 1))
((index ...)
(let f ((i 1) (ids (syntax (id1 ... id2 ...))))
(if (null? ids)
'()
(cons i (f (+ i 1) (cdr ids)))))))
(syntax (begin
(define constructor
(lambda (id1 ...)
(let* ((id2 init) ...)
(vector 'name id1 ... id2 ...))))
(define predicate
(lambda (x)
(and (vector? x)
(= (vector-length x) structure-length)
(eq? (vector-ref x 0) 'name))))
(define access
(lambda (x)
(vector-ref x index)))
...
; define macro accessors this way:
; (define-syntax access
; (syntax-case x ()
; ((_ x)
; (syntax (vector-ref x index))))))
; ...
(define assign
(lambda (x update)
(vector-set! x index update)))
...)))))))