41 lines
1.1 KiB
Scheme
41 lines
1.1 KiB
Scheme
;;; Ported from Scheme 48 1.9. See file COPYING for notices and license.
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;;;
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;;; Port Author: Andrew Whatson
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;;;
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;;; Original Authors: Richard Kelsey, Jonathan Rees
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;;;
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;;; scheme48-1.9.2/scheme/alt/locations.scm
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;;;
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;;; Locations
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(define-module (prescheme locations)
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#:use-module (srfi srfi-9)
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#:use-module (prescheme record-discloser)
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#:export (location?
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location-defined?
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location-assigned?
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location-id
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set-location-id!
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make-undefined-location
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set-location-defined?!
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contents
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set-contents!))
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(define-record-type :location
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(make-location id defined? contents)
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location?
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(id location-id set-location-id!)
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(defined? location-defined? set-defined?!)
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(contents contents set-contents!))
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(define-record-discloser :location
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(lambda (l) `(location ,(location-id l))))
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(define (make-undefined-location id)
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(make-location id #f '*empty*))
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(define (set-location-defined?! loc ?)
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(set-defined?! loc ?)
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(if (not ?)
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(set-contents! loc '*empty*)))
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