;;; rtree.el --- functions for manipulating range trees
-;; Copyright (C) 2010 Free Software Foundation, Inc.
+
+;; Copyright (C) 2010-2012 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; GNU Emacs 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 3, or (at your option)
-;; any later version.
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
;; GNU Emacs 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
+;; 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, Inc., 51 Franklin Street, Fifth Floor,
-;; Boston, MA 02110-1301, USA.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
((and (>= number (rtree-low tree))
(<= number (rtree-high tree)))
(setq tree nil))
- ;; Extend the low range.
- ((= number (1- (rtree-low tree)))
- (rtree-set-low tree number)
- ;; Check whether we need to merge this node with the child.
- (when (and (rtree-left tree)
- (= (rtree-high (rtree-left tree)) (1- number)))
- ;; Extend the range to the low from the child.
- (rtree-set-low tree (rtree-low (rtree-left tree)))
- ;; The child can't have a right child, so just transplant the
- ;; child's left tree to our left tree.
- (rtree-set-left tree (rtree-left (rtree-left tree))))
- (setq tree nil))
- ;; Extend the high range.
- ((= number (1+ (rtree-high tree)))
- (rtree-set-high tree number)
- ;; Check whether we need to merge this node with the child.
- (when (and (rtree-right tree)
- (= (rtree-low (rtree-right tree)) (1+ number)))
- ;; Extend the range to the high from the child.
- (rtree-set-high tree (rtree-high (rtree-right tree)))
- ;; The child can't have a left child, so just transplant the
- ;; child's left right to our right tree.
- (rtree-set-right tree (rtree-right (rtree-right tree))))
- (setq tree nil))
((< number (rtree-low tree))
- (if (rtree-left tree)
- (setq tree (rtree-left tree))
+ (cond
+ ;; Extend the low range.
+ ((= number (1- (rtree-low tree)))
+ (rtree-set-low tree number)
+ ;; Check whether we need to merge this node with the child.
+ (when (and (rtree-left tree)
+ (= (rtree-high (rtree-left tree)) (1- number)))
+ ;; Extend the range to the low from the child.
+ (rtree-set-low tree (rtree-low (rtree-left tree)))
+ ;; The child can't have a right child, so just transplant the
+ ;; child's left tree to our left tree.
+ (rtree-set-left tree (rtree-left (rtree-left tree))))
+ (setq tree nil))
+ ;; Descend further to the left.
+ ((rtree-left tree)
+ (setq tree (rtree-left tree)))
+ ;; Add a new node.
+ (t
(let ((new-node (rtree-make-node)))
(rtree-set-low new-node number)
(rtree-set-high new-node number)
(rtree-set-left tree new-node)
- (setq tree nil))))
+ (setq tree nil)))))
(t
- (if (rtree-right tree)
- (setq tree (rtree-right tree))
+ (cond
+ ;; Extend the high range.
+ ((= number (1+ (rtree-high tree)))
+ (rtree-set-high tree number)
+ ;; Check whether we need to merge this node with the child.
+ (when (and (rtree-right tree)
+ (= (rtree-low (rtree-right tree)) (1+ number)))
+ ;; Extend the range to the high from the child.
+ (rtree-set-high tree (rtree-high (rtree-right tree)))
+ ;; The child can't have a left child, so just transplant the
+ ;; child's left right to our right tree.
+ (rtree-set-right tree (rtree-right (rtree-right tree))))
+ (setq tree nil))
+ ;; Descend further to the right.
+ ((rtree-right tree)
+ (setq tree (rtree-right tree)))
+ ;; Add a new node.
+ (t
(let ((new-node (rtree-make-node)))
(rtree-set-low new-node number)
(rtree-set-high new-node number)
(rtree-set-right tree new-node)
- (setq tree nil)))))))
+ (setq tree nil))))))))
+
+(defun rtree-delq (tree number)
+ "Remove NUMBER from TREE destructively. Returns the new tree."
+ (let ((result tree)
+ prev)
+ (while tree
+ (cond
+ ((< number (rtree-low tree))
+ (setq prev tree
+ tree (rtree-left tree)))
+ ((> number (rtree-high tree))
+ (setq prev tree
+ tree (rtree-right tree)))
+ ;; The number is in this node.
+ (t
+ (cond
+ ;; The only entry; delete the node.
+ ((= (rtree-low tree) (rtree-high tree))
+ (cond
+ ;; Two children. Replace with successor value.
+ ((and (rtree-left tree) (rtree-right tree))
+ (let ((parent tree)
+ (successor (rtree-right tree)))
+ (while (rtree-left successor)
+ (setq parent successor
+ successor (rtree-left successor)))
+ ;; We now have the leftmost child of our right child.
+ (rtree-set-range tree (rtree-range successor))
+ ;; Transplant the child (if any) to the parent.
+ (rtree-set-left parent (rtree-right successor))))
+ (t
+ (let ((rest (or (rtree-left tree)
+ (rtree-right tree))))
+ ;; One or zero children. Remove the node.
+ (cond
+ ((null prev)
+ (setq result rest))
+ ((eq (rtree-left prev) tree)
+ (rtree-set-left prev rest))
+ (t
+ (rtree-set-right prev rest)))))))
+ ;; The lowest in the range; just adjust.
+ ((= number (rtree-low tree))
+ (rtree-set-low tree (1+ number)))
+ ;; The highest in the range; just adjust.
+ ((= number (rtree-high tree))
+ (rtree-set-high tree (1- number)))
+ ;; We have to split this range.
+ (t
+ (let ((new-node (rtree-make-node)))
+ (rtree-set-low new-node (rtree-low tree))
+ (rtree-set-high new-node (1- number))
+ (rtree-set-low tree (1+ number))
+ (cond
+ ;; Two children; insert the new node as the predecessor
+ ;; node.
+ ((and (rtree-left tree) (rtree-right tree))
+ (let ((predecessor (rtree-left tree)))
+ (while (rtree-right predecessor)
+ (setq predecessor (rtree-right predecessor)))
+ (rtree-set-right predecessor new-node)))
+ ((rtree-left tree)
+ (rtree-set-right new-node tree)
+ (rtree-set-left new-node (rtree-left tree))
+ (rtree-set-left tree nil)
+ (cond
+ ((null prev)
+ (setq result new-node))
+ ((eq (rtree-left prev) tree)
+ (rtree-set-left prev new-node))
+ (t
+ (rtree-set-right prev new-node))))
+ (t
+ (rtree-set-left tree new-node))))))
+ (setq tree nil))))
+ result))
(defun rtree-extract (tree)
"Convert TREE to range form."
(setq tree (rtree-left tree))))
result))
+(defun rtree-length (tree)
+ "Return the number of numbers stored in TREE."
+ (if (null tree)
+ 0
+ (+ (rtree-length (rtree-left tree))
+ (1+ (- (rtree-high tree)
+ (rtree-low tree)))
+ (rtree-length (rtree-right tree)))))
+
(provide 'rtree)
;;; rtree.el ends here
projects / gnus / blobdiff