mapping.lisp - clic - Clic is an command line interactive client for gopher written in Common LISP
 (HTM) git clone git://bitreich.org/clic/ git://enlrupgkhuxnvlhsf6lc3fziv5h2hhfrinws65d7roiv6bfj7d652fid.onion/clic/
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       ---
       mapping.lisp (2910B)
       ---
            1 ;;;; -*- Mode: lisp; indent-tabs-mode: nil -*-
            2 ;;;
            3 ;;; mapping.lisp --- An example for mapping Lisp objects to ints.
            4 ;;;
            5 ;;; Copyright (C) 2007, Luis Oliveira  <loliveira@common-lisp.net>
            6 ;;;
            7 ;;; Permission is hereby granted, free of charge, to any person
            8 ;;; obtaining a copy of this software and associated documentation
            9 ;;; files (the "Software"), to deal in the Software without
           10 ;;; restriction, including without limitation the rights to use, copy,
           11 ;;; modify, merge, publish, distribute, sublicense, and/or sell copies
           12 ;;; of the Software, and to permit persons to whom the Software is
           13 ;;; furnished to do so, subject to the following conditions:
           14 ;;;
           15 ;;; The above copyright notice and this permission notice shall be
           16 ;;; included in all copies or substantial portions of the Software.
           17 ;;;
           18 ;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
           19 ;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
           20 ;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
           21 ;;; NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
           22 ;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
           23 ;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
           24 ;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
           25 ;;; DEALINGS IN THE SOFTWARE.
           26 ;;;
           27 
           28 ;;; This is an example on how to tackle the problem of passing Lisp
           29 ;;; object identifiers to foreign code.  It is not a great example,
           30 ;;; but might be useful nevertheless.
           31 ;;;
           32 ;;; Requires trivial-garbage: <http://cliki.net/trivial-garbage>
           33 
           34 (defpackage #:cffi-mapping-test
           35   (:use #:common-lisp #:cffi #:trivial-garbage)
           36   (:export #:run))
           37 
           38 (in-package #:cffi-mapping-test)
           39 
           40 (define-foreign-type lisp-object-type ()
           41   ((weakp :initarg :weakp))
           42   (:actual-type :unsigned-int))
           43 
           44 (define-parse-method lisp-object (&key weak-mapping)
           45   (make-instance 'lisp-object-type :weakp weak-mapping))
           46 
           47 (defvar *regular-hashtable* (make-hash-table))
           48 (defvar *weak-hashtable* (make-weak-hash-table :weakness :value))
           49 (defvar *regular-counter* 0)
           50 (defvar *weak-counter* 0)
           51 
           52 (defun increment-counter (value)
           53   (mod (1+ value) (expt 2 (* 8 (foreign-type-size :unsigned-int)))))
           54 
           55 (define-modify-macro incf-counter () increment-counter)
           56 
           57 (defmethod translate-to-foreign (value (type lisp-object-type))
           58   (with-slots (weakp) type
           59     (let ((id (if weakp
           60                   (incf-counter *weak-counter*)
           61                   (incf-counter *regular-counter*)))
           62           (ht (if weakp *weak-hashtable* *regular-hashtable*)))
           63       (setf (gethash id ht) value)
           64       id)))
           65 
           66 (defmethod translate-from-foreign (int (type lisp-object-type))
           67   (with-slots (weakp) type
           68     (gethash int (if weakp *weak-hashtable* *regular-hashtable*))))
           69 
           70 ;;;; Silly example.
           71 
           72 (defctype weak-mapping (lisp-object :weak-mapping t))
           73 
           74 ;;; (run) => #<FUNCTION (LAMBDA (X)) {11AB46F5}>
           75 (defun run ()
           76   (foreign-funcall "abs" weak-mapping (lambda (x) x) weak-mapping))