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|
#| Copyright (C) 2025 Peter McGoron
|
| Permission is hereby granted, free of charge, to any person obtaining a
| copy of this software and associated documentation files (the
| "Software"), to deal in the Software without restriction, including
| without limitation the rights to use, copy, modify, merge, publish,
| distribute, sublicense, and/or sell copies of the Software, and to
| permit persons to whom the Software is furnished to do so, subject to
| the following conditions:
|
| The above copyright notice and this permission notice (including the
| next paragraph) shall be included in all copies or substantial portions
| of the Software.
|
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
| OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
| MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
| IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
| CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
| TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
| SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|#
(define-library (srfi 259)
(import (scheme base) (scheme write)
integer-map
(chicken base)
(chicken foreign)
(chicken condition)
(chicken fixnum))
(export define-procedure-tag)
(include "lowlevel.scm")
(begin
(define is-type? (condition-predicate 'type))
(define-syntax define-procedure-tag
(syntax-rules ()
((define-procedure-tag constructor predicate? accessor)
;; This uses `define-values` instead of a define for `id` because
;; Chicken breaks hygiene for top-level `define` names.
(define-values (constructor predicate? accessor)
(let ((id (unique-id)))
(values
;; constructor
(lambda (tag proc)
(handle-exceptions E (abort
(make-composite-condition
(make-property-condition
'exn
'location
(quote constructor)
'arguments
(list proc)
'message
"not a procedure")
E))
(set-tagged-mapping proc id tag)))
;; predicate?
(lambda (proc)
(cond
((not (procedure? proc)) #f)
((get-mapping proc)
=> (cut fxmapping-contains? <> id))
(else #f)))
;; accessor
(lambda (proc)
(define map
(handle-exceptions E (abort
(make-composite-condition
(make-property-condition
'exn
'location
(quote accessor)
'arguments
(list proc)
'message
"not a procedure")
E))
(get-mapping proc)))
(define (raise-error)
(abort
(make-composite-condition
(make-property-condition 'exn
'location
(quote accessor)
'arguments
(list proc)
'message
"tag was not found")
(make-property-condition 'assertion))))
(if map
(fxmapping-ref map id raise-error)
(raise-error)))))))))))
|
