77 lines
2.8 KiB
Common Lisp
77 lines
2.8 KiB
Common Lisp
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;;;; -*- Mode: lisp; indent-tabs-mode: nil -*-
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;;;
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;;; mapping.lisp --- An example for mapping Lisp objects to ints.
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;;;
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;;; Copyright (C) 2007, Luis Oliveira <loliveira@common-lisp.net>
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;;;
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;;; Permission is hereby granted, free of charge, to any person
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;;; obtaining a copy of this software and associated documentation
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;;; files (the "Software"), to deal in the Software without
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;;; restriction, including without limitation the rights to use, copy,
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;;; modify, merge, publish, distribute, sublicense, and/or sell copies
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;;; of the Software, and to permit persons to whom the Software is
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;;; furnished to do so, subject to the following conditions:
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;;;
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;;; The above copyright notice and this permission notice shall be
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;;; included in all copies or substantial portions of the Software.
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;;;
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;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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;;; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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;;; DEALINGS IN THE SOFTWARE.
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;;;
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;;; This is an example on how to tackle the problem of passing Lisp
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;;; object identifiers to foreign code. It is not a great example,
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;;; but might be useful nevertheless.
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;;;
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;;; Requires trivial-garbage: <http://cliki.net/trivial-garbage>
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(defpackage #:cffi-mapping-test
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(:use #:common-lisp #:cffi #:trivial-garbage)
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(:export #:run))
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(in-package #:cffi-mapping-test)
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(define-foreign-type lisp-object-type ()
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((weakp :initarg :weakp))
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(:actual-type :unsigned-int))
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(define-parse-method lisp-object (&key weak-mapping)
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(make-instance 'lisp-object-type :weakp weak-mapping))
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(defvar *regular-hashtable* (make-hash-table))
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(defvar *weak-hashtable* (make-weak-hash-table :weakness :value))
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(defvar *regular-counter* 0)
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(defvar *weak-counter* 0)
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(defun increment-counter (value)
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(mod (1+ value) (expt 2 (* 8 (foreign-type-size :unsigned-int)))))
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(define-modify-macro incf-counter () increment-counter)
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(defmethod translate-to-foreign (value (type lisp-object-type))
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(with-slots (weakp) type
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(let ((id (if weakp
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(incf-counter *weak-counter*)
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(incf-counter *regular-counter*)))
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(ht (if weakp *weak-hashtable* *regular-hashtable*)))
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(setf (gethash id ht) value)
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id)))
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(defmethod translate-from-foreign (int (type lisp-object-type))
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(with-slots (weakp) type
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(gethash int (if weakp *weak-hashtable* *regular-hashtable*))))
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;;;; Silly example.
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(defctype weak-mapping (lisp-object :weak-mapping t))
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;;; (run) => #<FUNCTION (LAMBDA (X)) {11AB46F5}>
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(defun run ()
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(foreign-funcall "abs" weak-mapping (lambda (x) x) weak-mapping))
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