Singly-linked list/Element definition: Difference between revisions
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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. |
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. |
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==[[Pop11]]== |
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[[Category:Pop11]] |
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List are built in into Pop11, so normally on would just use them: |
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;;; Use shorthand syntax to createlist. |
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lvars l1 = [1 2 three 'four']; |
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;;; Allocate a single list node, with value field 1 and the link field |
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;;; pointing to empty list |
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lvars l2 = cons(1, []); |
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;;; print first element of l1 |
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front(l1) => |
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;;; print the rest of l1 |
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back(l1) => |
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;;; Use index notation to access third element |
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l1(3) => |
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;;; modify link field of l2 to point to l1 |
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l1 -> back(l2); |
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;;; Print l2 |
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l2 => |
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If however one wants to definie equivalent user-defined type, one |
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can do this: |
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uses objectclass; |
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define :class ListNode; |
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slot value = []; |
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slot next = []; |
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enddefine; |
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;;; Allocate new node and assign to l1 |
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newListNode() -> l1; |
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;;; Print it |
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l1 => |
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;;; modify value |
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1 -> value(l1); |
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l1 => |
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;;; Allocate new node with initialized values and assign to link field |
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;;; of l1 |
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consListNode(2, []) -> next(l1); |
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l1 => |
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