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Singly-linked list/Element definition: Difference between revisions
Singly-linked list/Element definition (view source)
Revision as of 22:34, 12 May 2007
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Due to Forth's lack of typechecking, 'b' in the above examples does not have to be an actual cell, but can instead be the head pointer of the list.
==[[Pop11]]==
[[Category:Pop11]]
List are built in into Pop11, so normally on would just use them:
;;; Use shorthand syntax to createlist.
lvars l1 = [1 2 three 'four'];
;;; Allocate a single list node, with value field 1 and the link field
;;; pointing to empty list
lvars l2 = cons(1, []);
;;; print first element of l1
front(l1) =>
;;; print the rest of l1
back(l1) =>
;;; Use index notation to access third element
l1(3) =>
;;; modify link field of l2 to point to l1
l1 -> back(l2);
;;; Print l2
l2 =>
If however one wants to definie equivalent user-defined type, one
can do this:
uses objectclass;
define :class ListNode;
slot value = [];
slot next = [];
enddefine;
;;; Allocate new node and assign to l1
newListNode() -> l1;
;;; Print it
l1 =>
;;; modify value
1 -> value(l1);
l1 =>
;;; Allocate new node with initialized values and assign to link field
;;; of l1
consListNode(2, []) -> next(l1);
l1 =>
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