Deepcopy: Difference between revisions
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let newtree = tree.clone();
}</lang>
=={{header|Scheme}}==
<lang Scheme>
(define (deep-copy-1 exp)
;; basic version that copies an arbitrary tree made up of pairs
(cond ((pair? exp)
(cons (deep-copy-1 (car exp))
(deep-copy-1 (cdr exp))))
;; cases for extra container data types can be
;; added here, like vectors and so on
(else ;; atomic objects
(if (string? exp)
(string-copy exp)
exp))))
(define (deep-copy-2 exp)
(let ((sharing (make-hash-table)))
(let loop ((exp exp))
(cond ((pair? exp)
(cond ((get-hash-table sharing exp #f)
=> (lambda (copy)
copy))
(else
(let ((res (cons #f #f)))
(put-hash-table! sharing exp res)
(set-car! res (loop (car exp)))
(set-cdr! res (loop (cdr exp)))
res))))
(else
(if (string? exp)
(string-copy exp)
exp))))))
(define t1 '(a b c d))
(define t2 (list #f))
(set-car! t2 t2)
(define t2b (list #f))
(set-car! t2b t2b)
(define t3 (list #f #f))
(set-car! t3 t3)
(set-car! (cdr t3) t3)
(define t4 (list t2 t2b))
;> (print-graph #t)
;> (deep-copy-2 t1)
;(a b c d)
;> (deep-copy-2 t2)
;#0=(#0#)
;> (deep-copy-2 t3)
;#0=(#0# #0#)
;> (deep-copy-2 t4)
;(#0=(#0#) #1=(#1#))
</lang>
=={{header|Sidef}}==
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