112 lines
3.6 KiB
Scheme
112 lines
3.6 KiB
Scheme
#| -*-Scheme-*-
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Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
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1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
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2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
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2017, 2018, 2019, 2020 Massachusetts Institute of Technology
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This file is part of MIT/GNU Scheme.
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MIT/GNU Scheme 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 of the License, or (at
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your option) any later version.
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MIT/GNU Scheme is distributed in the hope that it will be useful, but
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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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You should have received a copy of the GNU General Public License
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along with MIT/GNU Scheme; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
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USA.
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|#
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;;;; Class/Object System
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;;; ******************************************************************
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;;; This software is intended for use in the Edwin window system only.
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;;; Don't think about using it for anything else, since it is not, and
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;;; likely will not ever, be supported as a part of the Scheme system.
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;;; ******************************************************************
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(define-structure (class (constructor %make-class))
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(name false read-only true)
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(superclass false read-only true)
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object-size
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instance-transforms
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(methods false read-only true))
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(define (class-method class name)
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(class-methods/ref (class-methods class) name))
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(define (class-methods/ref methods name)
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(or (method-lookup methods name)
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(error "Unknown method:" name)))
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(define (method-lookup methods name)
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(let loop ((methods methods))
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(and methods
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(let ((entry (assq name (car methods))))
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(if entry
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(cdr entry)
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(loop (cdr methods)))))))
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(define (class-method-define class name method)
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(let ((methods (class-methods class)))
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(let ((entry (assq name (car methods))))
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(if entry
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(set-cdr! entry method)
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(set-car! methods (cons (cons name method) (car methods))))))
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name)
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(define-integrable (usual-method class name)
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(class-method (class-superclass class) name))
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(define (subclass? class class*)
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(or (eq? class class*)
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(let loop ((class (class-superclass class)))
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(and class
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(or (eq? class class*)
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(loop (class-superclass class)))))))
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(define (make-object class)
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(if (not (class? class))
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(error:wrong-type-argument class "class" 'MAKE-OBJECT))
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(let ((object (make-vector (class-object-size class) false)))
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(vector-set! object 0 class)
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object))
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(define (object? object)
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(and (vector? object)
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(not (zero? (vector-length object)))
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(class? (vector-ref object 0))))
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(define (object-of-class? class object)
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(and (vector? object)
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(not (zero? (vector-length object)))
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(eq? class (vector-ref object 0))))
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(define-integrable (object-class object)
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(vector-ref object 0))
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(define-integrable (object-methods object)
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(class-methods (object-class object)))
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(define-integrable (object-method object name)
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(class-method (object-class object) name))
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(define (send object operation . args)
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(apply (object-method object operation) object args))
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(define (send-if-handles object operation . args)
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(let ((method (method-lookup (object-methods object) operation)))
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(and method (apply method object args))))
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(define (send-usual class object operation . args)
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(apply (usual-method class operation) object args))
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