copy-tree

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)) 

See Also:

tree-equal

Expanded Reference: copy-tree

tip

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(copy-tree )