source: branches/streams/abcl/src/org/armedbear/lisp/map-into.lisp

;;; map-into.lisp
;;;
;;; Copyright (C) 2003 Peter Graves
;;; $Id: map-into.lisp 11391 2008-11-15 22:38:34Z vvoutilainen $
;;;
;;; 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.

(in-package "COMMON-LISP")

(export 'map-into)

;;; MAP-INTO (from CMUCL)

(defun map-into (result-sequence function &rest sequences)
  (let* ((fp-result
    (and (arrayp result-sequence)
         (array-has-fill-pointer-p result-sequence)))
   (len (apply #'min
         (if fp-result
       (array-dimension result-sequence 0)
       (length result-sequence))
         (mapcar #'length sequences))))

    (when fp-result
      (setf (fill-pointer result-sequence) len))

    (dotimes (index len)
      (setf (elt result-sequence index)
      (apply function
       (mapcar #'(lambda (seq) (elt seq index))
         sequences)))))
  result-sequence)