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;;;; elib-node.el,v 1.2 1992/04/07 20:49:16 berliner Exp
;;;; This file implements the nodes used in binary trees and
;;;; doubly linked lists
;;;;
;;;; Copyright (C) 1991 Inge Wallin
;;;;
;;;; 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 1, 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 Emacs; see the file COPYING. If not, write to
;;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;;;;
;;;; Author: Inge Wallin
;;;;
;;;
;;; A node is implemented as an array with three elements, using
;;; (elt node 0) as the left pointer
;;; (elt node 1) as the right pointer
;;; (elt node 2) as the data
;;;
;;; Some types of trees, e.g. AVL trees, need bigger nodes, but
;;; as long as the first three parts are the left pointer, the
;;; right pointer and the data field, these macros can be used.
;;;
(provide 'elib-node)
(defmacro elib-node-create (left right data)
"Create a tree node from LEFT, RIGHT and DATA."
(` (vector (, left) (, right) (, data))))
(defmacro elib-node-left (node)
"Return the left pointer of NODE."
(` (aref (, node) 0)))
(defmacro elib-node-right (node)
"Return the right pointer of NODE."
(` (aref (, node) 1)))
(defmacro elib-node-data (node)
"Return the data of NODE."
(` (aref (, node) 2)))
(defmacro elib-node-set-left (node newleft)
"Set the left pointer of NODE to NEWLEFT."
(` (aset (, node) 0 (, newleft))))
(defmacro elib-node-set-right (node newright)
"Set the right pointer of NODE to NEWRIGHT."
(` (aset (, node) 1 (, newright))))
(defmacro elib-node-set-data (node newdata)
"Set the data of NODE to NEWDATA."
(` (aset (, node) 2 (, newdata))))
(defmacro elib-node-branch (node branch)
"Get value of a branch of a node.
NODE is the node, and BRANCH is the branch.
0 for left pointer, 1 for right pointer and 2 for the data."
(` (aref (, node) (, branch))))
(defmacro elib-node-set-branch (node branch newval)
"Set value of a branch of a node.
NODE is the node, and BRANCH is the branch.
0 for left pointer, 1 for the right pointer and 2 for the data.
NEWVAL is new value of the branch."
(` (aset (, node) (, branch) (, newval))))
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