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Common Lisp implementation running on the JVM
;;; define-modify-macro.lisp
;;;
;;; Copyright (C) 2003-2005 Peter Graves
;;; $Id$
;;;
;;; This program is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License
;;; as published by the Free Software Foundation; either version 2
;;; of the License, or (at your option) any later version.
;;;
;;; This program 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 General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program; if not, write to the Free Software
;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;;;
;;; As a special exception, the copyright holders of this library give you
;;; permission to link this library with independent modules to produce an
;;; executable, regardless of the license terms of these independent
;;; modules, and to copy and distribute the resulting executable under
;;; terms of your choice, provided that you also meet, for each linked
;;; independent module, the terms and conditions of the license of that
;;; module. An independent module is a module which is not derived from
;;; or based on this library. If you modify this library, you may extend
;;; this exception to your version of the library, but you are not
;;; obligated to do so. If you do not wish to do so, delete this
;;; exception statement from your version.
;;; Adapted from SBCL.
(in-package #:system)
;; FIXME See section 5.1.3.
(defmacro define-modify-macro (name lambda-list function &optional doc-string)
"Creates a new read-modify-write macro like PUSH or INCF."
(let ((other-args nil)
(rest-arg nil)
(env (gensym))
(reference (gensym)))
;; Parse out the variable names and &REST arg from the lambda list.
(do ((ll lambda-list (cdr ll))
(arg nil))
((null ll))
(setq arg (car ll))
(cond ((eq arg '&optional))
((eq arg '&rest)
(if (symbolp (cadr ll))
(setq rest-arg (cadr ll))
(error "Non-symbol &REST arg in definition of ~S." name))
(if (null (cddr ll))
(return nil)
(error "Illegal stuff after &REST argument in DEFINE-MODIFY-MACRO.")))
((memq arg '(&key &allow-other-keys &aux))
(error "~S not allowed in DEFINE-MODIFY-MACRO lambda list." arg))
((symbolp arg)
(push arg other-args))
((and (listp arg) (symbolp (car arg)))
(push (car arg) other-args))
(t (error "Illegal stuff in DEFINE-MODIFY-MACRO lambda list."))))
(setq other-args (nreverse other-args))
`(eval-when (:compile-toplevel :load-toplevel :execute)
(defmacro ,name (,reference ,@lambda-list &environment ,env)
,doc-string
(multiple-value-bind (dummies vals newval setter getter)
(get-setf-expansion ,reference ,env)
(do ((d dummies (cdr d))
(v vals (cdr v))
(let-list nil (cons (list (car d) (car v)) let-list)))
((null d)
(push (list (car newval)
,(if rest-arg
`(list* ',function getter ,@other-args ,rest-arg)
`(list ',function getter ,@other-args)))
let-list)
`(let* ,(nreverse let-list)
,setter))))))))
(define-modify-macro incf-complex (&optional (delta 1)) +
"The first argument is some location holding a number. This number is
incremented by the second argument, DELTA, which defaults to 1.")
(define-modify-macro decf-complex (&optional (delta 1)) -
"The first argument is some location holding a number. This number is
decremented by the second argument, DELTA, which defaults to 1.")
(defmacro incf (place &optional (delta 1))
(cond ((symbolp place)
(cond ((constantp delta)
`(setq ,place (+ ,place ,delta)))
(t
;; See section 5.1.3.
(let ((temp (gensym)))
`(let ((,temp ,delta))
(setq ,place (+ ,place ,temp)))))))
((and (consp place) (eq (car place) 'THE))
(let ((res (gensym)))
`(let ((,res (the ,(second place) (+ ,place ,delta))))
(setf ,(third place) ,res))))
(t
`(incf-complex ,place ,delta))))
(defmacro decf (place &optional (delta 1))
(cond ((symbolp place)
(cond ((constantp delta)
`(setq ,place (- ,place ,delta)))
(t
;; See section 5.1.3.
(let ((temp (gensym)))
`(let ((,temp ,delta))
(setq ,place (- ,place ,temp)))))))
((and (consp place) (eq (car place) 'THE))
(let ((res (gensym)))
`(let ((,res (the ,(second place) (- ,place ,delta))))
(setf ,(third place) ,res))))
(t
`(decf-complex ,place ,delta))))