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;;; "structure.scm" syntax-case structure macros
;;; Copyright (C) 1992 R. Kent Dybvig
;;;
;;; Permission to copy this software, in whole or in part, to use this
;;; software for any lawful purpose, and to redistribute this software
;;; is granted subject to the restriction that all copies made of this
;;; software must include this copyright notice in full. This software
;;; is provided AS IS, with NO WARRANTY, EITHER EXPRESS OR IMPLIED,
;;; INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY
;;; OR FITNESS FOR ANY PARTICULAR PURPOSE. IN NO EVENT SHALL THE
;;; AUTHORS BE LIABLE FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES OF ANY
;;; NATURE WHATSOEVER.
;;; 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
;@ A syntax-case macro:
(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 (syntax name) "-" x "-set!"))
(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)))
...)))))))
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