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116 lines
3.9 KiB
Scheme
116 lines
3.9 KiB
Scheme
;;; srfi-9.scm --- define-record-type
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;; Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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;;
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;; This program is free software; you can redistribute it and/or
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;; modify it under the terms of the GNU General Public License as
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;; published by the Free Software Foundation; either version 2, or
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;; (at your option) any later version.
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;;
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;; General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public License
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;; along with this software; see the file COPYING. If not, write to
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;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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;; Boston, MA 02111-1307 USA
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;;
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;; As a special exception, the Free Software Foundation gives permission
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;; for additional uses of the text contained in its release of GUILE.
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;;
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;; The exception is that, if you link the GUILE library with other files
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;; to produce an executable, this does not by itself cause the
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;; resulting executable to be covered by the GNU General Public License.
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;; Your use of that executable is in no way restricted on account of
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;; linking the GUILE library code into it.
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;;
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;; This exception does not however invalidate any other reasons why
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;; the executable file might be covered by the GNU General Public License.
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;;
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;; This exception applies only to the code released by the
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;; Free Software Foundation under the name GUILE. If you copy
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;; code from other Free Software Foundation releases into a copy of
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;; GUILE, as the General Public License permits, the exception does
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;; not apply to the code that you add in this way. To avoid misleading
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;; anyone as to the status of such modified files, you must delete
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;; this exception notice from them.
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;;
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;; If you write modifications of your own for GUILE, it is your choice
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;; whether to permit this exception to apply to your modifications.
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;; If you do not wish that, delete this exception notice.
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;;; Commentary:
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;; This module exports the syntactic form `define-record-type', which
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;; is the means for creating record types defined in SRFI-9.
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;;
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;; The syntax of a record type definition is:
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;;
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;; <record type definition>
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;; -> (define-record-type <type name>
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;; (<constructor name> <field tag> ...)
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;; <predicate name>
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;; <field spec> ...)
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;;
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;; <field spec> -> (<field tag> <accessor name>)
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;; -> (<field tag> <accessor name> <modifier name>)
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;;
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;; <field tag> -> <identifier>
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;; <... name> -> <identifier>
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;;
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;; Usage example:
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;;
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;; guile> (use-modules (srfi srfi-9))
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;; guile> (define-record-type :foo (make-foo x) foo?
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;; (x get-x) (y get-y set-y!))
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;; guile> (define f (make-foo 1))
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;; guile> f
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;; #<:foo x: 1 y: #f>
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;; guile> (get-x f)
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;; 1
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;; guile> (set-y! f 2)
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;; 2
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;; guile> (get-y f)
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;; 2
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;; guile> f
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;; #<:foo x: 1 y: 2>
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;; guile> (foo? f)
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;; #t
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;; guile> (foo? 1)
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;; #f
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;;; Code:
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(define-module (srfi srfi-9)
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:export-syntax (define-record-type))
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(cond-expand-provide (current-module) '(srfi-9))
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(define-macro (define-record-type type-name constructor/field-tag
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predicate-name . field-specs)
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`(begin
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(define ,type-name
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(make-record-type ',type-name ',(map car field-specs)))
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(define ,(car constructor/field-tag)
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(record-constructor ,type-name ',(cdr constructor/field-tag)))
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(define ,predicate-name
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(record-predicate ,type-name))
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,@(map
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(lambda (spec)
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(cond
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((= (length spec) 2)
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`(define ,(cadr spec)
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(record-accessor ,type-name ',(car spec))))
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((= (length spec) 3)
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`(begin
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(define ,(cadr spec)
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(record-accessor ,type-name ',(car spec)))
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(define ,(caddr spec)
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(record-modifier ,type-name ',(car spec)))))
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(else
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(error "invalid field spec " spec))))
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field-specs)))
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;;; srfi-9.scm ends here
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