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105 lines
3.8 KiB
Scheme
105 lines
3.8 KiB
Scheme
;;; installed-scm-file
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;;;; Copyright (C) 1995, 1996, 1998, 2001, 2003 Free Software Foundation, Inc.
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;;;;
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;;;; This program is free software; you can redistribute it and/or modify
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;;;; it under the terms of the GNU General Public License as published by
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;;;; the Free Software Foundation; either version 2, or (at your option)
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;;;; 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
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;;;; GNU 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., 51 Franklin Street, Fifth Floor,
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;;;; Boston, MA 02110-1301 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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;;;;
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(define-module (ice-9 hcons)
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:export (hashq-cons-hash hashq-cons-assoc hashq-cons-get-handle
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hashq-cons-create-handle! hashq-cons-ref hashq-cons-set! hashq-cons
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hashq-conser make-gc-buffer))
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;;; {Eq? hash-consing}
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;;;
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;;; A hash conser maintains a private universe of pairs s.t. if
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;;; two cons calls pass eq? arguments, the pairs returned are eq?.
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;;;
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;;; A hash conser does not contribute life to the pairs it returns.
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;;;
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(define (hashq-cons-hash pair n)
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(modulo (logxor (hashq (car pair) 4194303)
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(hashq (cdr pair) 4194303))
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n))
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(define (hashq-cons-assoc key l)
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(and (not (null? l))
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(or (and (pair? l) ; If not a pair, use its cdr?
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(pair? (car l))
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(pair? (caar l))
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(eq? (car key) (caaar l))
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(eq? (cdr key) (cdaar l))
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(car l))
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(hashq-cons-assoc key (cdr l)))))
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(define (hashq-cons-get-handle table key)
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(hashx-get-handle hashq-cons-hash hashq-cons-assoc table key))
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(define (hashq-cons-create-handle! table key init)
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(hashx-create-handle! hashq-cons-hash hashq-cons-assoc table key init))
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(define (hashq-cons-ref table key)
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(hashx-ref hashq-cons-hash hashq-cons-assoc table key #f))
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(define (hashq-cons-set! table key val)
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(hashx-set! hashq-cons-hash hashq-cons-assoc table key val))
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(define (hashq-cons table a d)
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(car (hashq-cons-create-handle! table (cons a d) #f)))
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(define (hashq-conser hash-tab-or-size)
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(let ((table (if (vector? hash-tab-or-size)
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hash-tab-or-size
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(make-doubly-weak-hash-table hash-tab-or-size))))
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(lambda (a d) (hashq-cons table a d))))
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(define (make-gc-buffer n)
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(let ((ring (make-list n #f)))
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(append! ring ring)
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(lambda (next)
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(set-car! ring next)
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(set! ring (cdr ring))
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next)))
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