--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lisp/skk/queue-m.el	Mon Aug 13 10:09:35 2007 +0200
@@ -0,0 +1,142 @@
+;;;; $Id: queue-m.el,v 1.1 1997/12/02 08:48:36 steve Exp $
+;;;; This file implements a simple FIFO queue using macros.
+
+;; Copyright (C) 1991-1995 Free Software Foundation
+
+;; Author: Inge Wallin <inge@lysator.liu.se>
+;; Maintainer: elib-maintainers@lysator.liu.se
+;; Created: before 12 May 1991
+;; Last Modified: $Date: 1997/12/02 08:48:36 $
+;; Keywords: extensions, lisp
+
+;;;;
+;;;; This file is part of the GNU Emacs lisp library, Elib.
+;;;;
+;;;; GNU Elib 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, or (at your option)
+;;;; any later version.
+;;;;
+;;;; GNU Elib 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 GNU Elib; see the file COPYING.  If not, write to
+;;;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;;;; Boston, MA 02111-1307, USA
+;;;;
+;;;; Author: Inge Wallin
+;;;; 
+
+;;; Commentary:
+
+;;; The queue is implemented as a two cons cell list, the first 
+;;; containing the tag 'QUEUE.  The car of the the second cons
+;;; cell points at the first element of the queue and the cdr points
+;;; at the last.  All entries and removals are done using destructive
+;;; functions.
+;;;
+;;; This file implements the short functions as macros for speed in 
+;;; compiled code.
+;;;
+
+
+;;; Code:
+
+;; Provide the function version and remove the macro version
+(provide 'queue-m)
+(setq features (delq 'queue-f features))
+
+
+;;; ================================================================
+
+
+(defmacro queue-create ()
+  "Create an empty fifo queue."
+  (` (cons 'QUEUE (cons nil nil))))
+
+
+(defmacro queue-p (queue)
+  "Return t if QUEUE is a queue, otherwise return nil."
+  (` (eq (car-safe (, queue)) 'QUEUE)))
+
+
+(defun queue-enqueue (queue element)
+  "Enter an element into a queue.
+Args: QUEUE ELEMENT"
+  (let ((elementcell (cons element nil)))
+    (if (null (car (cdr queue)))
+	;; QUEUE is empty
+	(setcar (cdr queue)
+		(setcdr (cdr queue) 
+			elementcell))
+      (setcdr (cdr (cdr queue))
+	      elementcell)
+      (setcdr (cdr queue)
+	      elementcell))))
+
+
+(defun queue-dequeue (queue)
+  "Remove the first element of QUEUE and return it.
+If QUEUE is empty, return nil and do nothing."
+  (if (car (cdr queue))
+      (prog1
+	  (car (car (cdr queue)))
+	(setcar (cdr queue)
+		(cdr (car (cdr queue))))
+	(if (null (car (cdr queue)))
+	    (setcdr (cdr queue) nil)))))
+
+
+(defmacro queue-empty (queue)
+  "Return t if QUEUE is empty, otherwise return nil."
+  (` (null (car (cdr (, queue))))))
+
+
+(defmacro queue-first (queue)
+  "Return the first element of QUEUE or nil if it is empty.
+The element is not removed."
+  (` (car-safe (car (cdr (, queue))))))
+
+
+(defmacro queue-nth (queue n)
+  "Return the nth element of a queue, but don't remove it.
+Args: QUEUE N
+If the length of the queue is less than N, return nil.
+
+The oldest element (the first one) has number 0."
+  (` (nth (, n) (car (cdr (, queue))))))
+
+
+(defmacro queue-last (queue)
+  "Return the last element of QUEUE or nil if it is empty."
+  (` (car-safe (cdr (cdr (, queue))))))
+
+
+(defmacro queue-all (queue)
+  "Return a list of all elements of QUEUE or nil if it is empty.
+The oldest element in the queue is the first in the list."
+  (` (car (cdr (, queue)))))
+
+
+(defun queue-copy (queue)
+  "Return a copy of QUEUE.  All entries in QUEUE are also copied."
+  (let* ((first  (copy-sequence (car (cdr queue))))
+	 (last first))
+    (while (cdr last)
+      (setq last (cdr last)))
+    (cons 'QUEUE (cons first last))))
+
+
+(defmacro queue-length (queue)
+  "Return the number of elements in QUEUE."
+  (` (length (car (cdr (, queue))))))
+
+
+(defmacro queue-clear (queue)
+  "Remove all elements from QUEUE."
+  (` (setcdr (, queue) (cons nil nil))))
+
+;;; queue-m.el ends here