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Allegro CL         ANSI Common Lisp 14 Conses 14.2 Dictionary of Conses

 14.2.10 copy-tree Function

Syntax:
copy-tree tree new-tree

Arguments and Values:
tree - a tree.

new-tree - a tree.

Description:
Creates a copy of a tree of conses.

If tree is not a cons, it is returned; otherwise, the result is a new cons of the results of calling copy-tree on the car and cdr of tree. In other words, all conses in the tree represented by tree are copied recursively, stopping only when non-conses are encountered.

copy-tree does not preserve circularities and the sharing of substructure.

Examples:
``` (setq object (list (cons 1 "one")
(cons 2 (list 'a 'b 'c)))) ((1 . "one") (2 A B C))
(setq object-too object) ((1 . "one") (2 A B C))
(setq copy-as-list (copy-list object))
(setq copy-as-alist (copy-alist object))
(setq copy-as-tree (copy-tree object))
(eq object object-too) true
(eq copy-as-tree object) false
(eql copy-as-tree object) false
(equal copy-as-tree object) true
(setf (first (cdr (second object))) "a"
(car (second object)) "two"
(car object) '(one . 1)) (ONE . 1)
object ((ONE . 1) ("two" "a" B C))
object-too ((ONE . 1) ("two" "a" B C))
copy-as-list ((1 . "one") ("two" "a" B C))
copy-as-alist ((1 . "one") (2 "a" B C))
copy-as-tree ((1 . "one") (2 A B C))
```         