121 lines
3.1 KiB
Scheme
121 lines
3.1 KiB
Scheme
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; -*- Mode: Scheme; Syntax: Scheme; Package: Scheme; -*-
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; Copyright (c) 1993, 1994 Richard Kelsey and Jonathan Rees. See file COPYING.
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; This is file schemetoc-record.scm.
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; Synchronize any changes with the other *record.scm files.
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;;;; Records
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(define (make-record-type type-id field-names)
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(define unique (lambda () the-descriptor))
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(define size (+ (length field-names) 1))
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(define (constructor . names-option)
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(let* ((names (if (null? names-option)
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field-names
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(car names-option)))
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(foo (cons unique
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(map (lambda (name) 'uninitialized) field-names)))
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(number-of-inits (length names))
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(indexes (map field-index names)))
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(lambda field-values
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(if (= (length field-values) number-of-inits)
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(let ((record (list->%record foo)))
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(for-each (lambda (index value)
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(%record-set! record index value))
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indexes
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field-values)
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(%record-methods-set! record usual-record-methods)
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record)
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(error "wrong number of arguments to record constructor"
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field-values type-id names)))))
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(define (predicate obj)
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(and (%record? obj)
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(= (%record-length obj) size)
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(eq? (%record-ref obj 0) unique)))
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(define (accessor name)
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(let ((i (field-index name)))
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(lambda (record)
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(if (predicate record) ;Faster: (eq? (%record-ref record 0) unique)
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(%record-ref record i)
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(error "invalid argument to record accessor"
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record type-id name)))))
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(define (modifier name)
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(let ((i (field-index name)))
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(lambda (record new-value)
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(if (predicate record) ;Faster: (eq? (%record-ref record 0) unique)
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(%record-set! record i new-value)
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(error "invalid argument to record modifier"
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record type-id name)))))
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(define (field-index name)
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(let loop ((l field-names) (i 1))
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(if (null? l)
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(error "bad field name" name)
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(if (eq? name (car l))
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i
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(loop (cdr l) (+ i 1))))))
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(define (discloser r) (list type-id))
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(define the-descriptor
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(lambda (request)
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(case request
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((constructor) constructor)
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((predicate) predicate)
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((accessor) accessor)
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((modifier) modifier)
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((identification) type-id)
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((field-names) field-names)
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((discloser) discloser)
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((set-discloser!) (lambda (d) (set! discloser d))))))
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the-descriptor)
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(define (record-type x)
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(if (%record? x)
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(let ((probe (%record-ref x 0)))
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(if (procedure? probe)
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(probe)
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#f))
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#f))
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(define (record-type-identification r-t)
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(r-t 'identification))
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(define (record-type-field-names r-t)
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(r-t 'field-names))
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(define (record-constructor r-t . names-option)
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(apply (r-t 'constructor) names-option))
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(define (record-predicate r-t)
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(r-t 'predicate))
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(define (record-accessor r-t field-name)
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((r-t 'accessor) field-name))
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(define (record-modifier r-t field-name)
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((r-t 'modifier) field-name))
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(define (define-record-discloser r-t proc)
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((r-t 'set-discloser!) proc))
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(define (disclose-record r)
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(((record-type r) 'discloser) r))
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(define usual-record-methods
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(list (cons '%to-write
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(lambda (r port indent levels length seen)
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(write-char #\# port)
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(write-char %record-prefix-char port)
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(list (disclose-record r))))))
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(set! %record-prefix-char #\~)
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