RosettaCodeData/Task/Pattern-matching/Common-Lisp/pattern-matching.lisp

40 lines
1.4 KiB
Common Lisp

(mapc #'use-package '(#:toadstool #:toadstool-system))
(defstruct (red-black-tree (:constructor tree (color left val right)))
color left val right)
(defcomponent tree (operator macro-mixin))
(defexpand tree (color left val right)
`(class red-black-tree red-black-tree-color ,color
red-black-tree-left ,left
red-black-tree-val ,val
red-black-tree-right ,right))
(pushnew 'tree *used-components*)
(defun balance (color left val right)
(toad-ecase (color left val right)
(('black (tree 'red (tree 'red a x b) y c) z d)
(tree 'red (tree 'black a x b) y
(tree 'black c z d)))
(('black (tree 'red a x (tree 'red b y c)) z d)
(tree 'red (tree 'black a x b) y (tree 'black c z d)))
(('black a x (tree 'red (tree 'red b y c) z d))
(tree 'red (tree 'black a x b) y (tree 'black c z d)))
(('black a x (tree 'red b y (tree 'red c z d)))
(tree 'red (tree 'black a x b) y (tree 'black c z d)))
((color a x b)
(tree color a x b))))
(defun %insert (x s)
(toad-ecase1 s
(nil (tree 'red nil x nil))
((tree color a y b)
(cond ((< x y)
(balance color (%insert x a) y b))
((> x y)
(balance color a y (%insert x b)))
(t s)))))
(defun insert (x s)
(toad-ecase1 (%insert x s)
((tree t a y b) (tree 'black a y b))))