;;;; -*- Mode: lisp; indent-tabs-mode: nil -*-
;;;
;;; utils.lisp --- Various utilities.
;;;

;;; Copyright (C) 2005-2008, Luis Oliveira  <loliveira(@)common-lisp.net>

;;;
;;; Permission is hereby granted, free of charge, to any person
;;; obtaining a copy of this software and associated documentation
;;; files (the "Software"), to deal in the Software without
;;; restriction, including without limitation the rights to use, copy,
;;; modify, merge, publish, distribute, sublicense, and/or sell copies
;;; of the Software, and to permit persons to whom the Software is
;;; furnished to do so, subject to the following conditions:
;;;
;;; The above copyright notice and this permission notice shall be
;;; included in all copies or substantial portions of the Software.
;;;
;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
;;; NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
;;; DEALINGS IN THE SOFTWARE.
;;;

(in-package #:cffi)

(defmacro discard-docstring (body-var &optional force)

  "Discards the first element of the list in body-var if it's a

string and the only element (or if FORCE is T)."
  `(when (and (stringp (car ,body-var)) (or ,force (cdr ,body-var)))

     (pop ,body-var)))

(defun single-bit-p (integer)
  "Answer whether INTEGER, which must be an integer, is a single
set twos-complement bit."
  (if (<= integer 0)

      nil                            ; infinite set bits for negatives
      (loop until (logbitp 0 integer)
            do (setf integer (ash integer -1))
            finally (return (zerop (ash integer -1))))))

;;; This function is here because it needs to be defined early. It's
;;; used by DEFINE-PARSE-METHOD and DEFCTYPE to warn users when
;;; they're defining types whose names belongs to the KEYWORD or CL
;;; packages.  CFFI itself gets to use keywords without a warning.

(defun warn-if-kw-or-belongs-to-cl (name)
  (let ((package (symbol-package name)))

    (when (and (not (eq *package* (find-package '#:cffi)))
               (member package '(#:common-lisp #:keyword)
                       :key #'find-package))

      (warn "Defining a foreign type named ~S.  This symbol belongs to the ~A ~
             package and that may interfere with other code using CFFI."
            name (package-name package)))))