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;;;; Copyright (C) 1999, 2001, 2006 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;
;; There are circularities here; you can't import (oop goops compile)
;; before (oop goops). So when compiling, make sure that things are
;; kosher.
(eval-when (compile) (resolve-module '(oop goops)))
(define-module (oop goops compile)
:use-module (oop goops)
:use-module (oop goops util)
:export (compute-cmethod)
:no-backtrace
)
;;;
;;; Method entries
;;;
(define code-table-lookup
(letrec ((check-entry (lambda (entry types)
(cond
((not (pair? entry)) (and (null? types) entry))
((null? types) #f)
(else
(and (eq? (car entry) (car types))
(check-entry (cdr entry) (cdr types))))))))
(lambda (code-table types)
(cond ((null? code-table) #f)
((check-entry (car code-table) types))
(else (code-table-lookup (cdr code-table) types))))))
(define (compute-cmethod methods types)
(or (code-table-lookup (slot-ref (car methods) 'code-table) types)
(let* ((method (car methods))
(cmethod (compile-method methods types))
(entry (append types cmethod)))
(slot-set! method 'code-table
(cons entry (slot-ref method 'code-table)))
cmethod)))
;;;
;;; Compiling next methods into method bodies
;;;
;;; So, for the reader: there basic idea is that, given that the
;;; semantics of `next-method' depend on the concrete types being
;;; dispatched, why not compile a specific procedure to handle each type
;;; combination that we see at runtime.
;;;
;;; In theory we can do much better than a bytecode compilation, because
;;; we know the *exact* types of the arguments. It's ideal for native
;;; compilation. A task for the future.
;;;
;;; I think this whole generic application mess would benefit from a
;;; strict MOP.
(define (compile-method methods types)
(let ((make-procedure (slot-ref (car methods) 'make-procedure)))
(if make-procedure
(make-procedure
(if (null? methods)
(lambda args
(no-next-method (method-generic-function (car methods)) args))
(compute-cmethod (cdr methods) types)))
(method-procedure (car methods)))))
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