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|
; -*- Mode: Scheme; Syntax: Scheme; Package: Scheme; -*-
; Part of Scheme 48 1.9. See file COPYING for notices and license.
; Authors: Richard Kelsey, Jonathan Rees
; This is file schemetoc-record.scm.
; Synchronize any changes with the other *record.scm files.
;;;; Records
(define (make-record-type type-id field-names)
(define unique (lambda () the-descriptor))
(define size (+ (length field-names) 1))
(define (constructor . names-option)
(let* ((names (if (null? names-option)
field-names
(car names-option)))
(foo (cons unique
(map (lambda (name) 'uninitialized) field-names)))
(number-of-inits (length names))
(indexes (map field-index names)))
(lambda field-values
(if (= (length field-values) number-of-inits)
(let ((record (list->%record foo)))
(for-each (lambda (index value)
(%record-set! record index value))
indexes
field-values)
(%record-methods-set! record usual-record-methods)
record)
(error "wrong number of arguments to record constructor"
field-values type-id names)))))
(define (predicate obj)
(and (%record? obj)
(= (%record-length obj) size)
(eq? (%record-ref obj 0) unique)))
(define (accessor name)
(let ((i (field-index name)))
(lambda (record)
(if (predicate record) ;Faster: (eq? (%record-ref record 0) unique)
(%record-ref record i)
(error "invalid argument to record accessor"
record type-id name)))))
(define (modifier name)
(let ((i (field-index name)))
(lambda (record new-value)
(if (predicate record) ;Faster: (eq? (%record-ref record 0) unique)
(%record-set! record i new-value)
(error "invalid argument to record modifier"
record type-id name)))))
(define (field-index name)
(let loop ((l field-names) (i 1))
(if (null? l)
(error "bad field name" name)
(if (eq? name (car l))
i
(loop (cdr l) (+ i 1))))))
(define (discloser r) (list type-id))
(define the-descriptor
(lambda (request)
(case request
((constructor) constructor)
((predicate) predicate)
((accessor) accessor)
((modifier) modifier)
((identification) type-id)
((field-names) field-names)
((discloser) discloser)
((set-discloser!) (lambda (d) (set! discloser d))))))
the-descriptor)
(define (record-type x)
(if (%record? x)
(let ((probe (%record-ref x 0)))
(if (procedure? probe)
(probe)
#f))
#f))
(define (record-type-identification r-t)
(r-t 'identification))
(define (record-type-field-names r-t)
(r-t 'field-names))
(define (record-constructor r-t . names-option)
(apply (r-t 'constructor) names-option))
(define (record-predicate r-t)
(r-t 'predicate))
(define (record-accessor r-t field-name)
((r-t 'accessor) field-name))
(define (record-modifier r-t field-name)
((r-t 'modifier) field-name))
(define (define-record-discloser r-t proc)
((r-t 'set-discloser!) proc))
(define (disclose-record r)
(((record-type r) 'discloser) r))
(define usual-record-methods
(list (cons '%to-write
(lambda (r port indent levels length seen)
(write-char #\# port)
(write-char %record-prefix-char port)
(list (disclose-record r))))))
(set! %record-prefix-char #\~)
|
