1. List Iterator Implementation
Lecture 33
Fri, Apr 13, 2007

2. List Traversals
To traverse a list is to move from one end to the other, “visiting” each node along the way.
Forward traversals go from head to tail
Reverse traversals go from tail to head.
The meaning of “visiting” a node is left unspecified at this point.
The meaning will be specified at the time of the traversal.
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List Iterators

3. The Traversal Function
Introduce a new List member function
The parameter, named visit, is a pointer to a function.
The function visit() has prototype
void traverse(ListIterator& it,
void (* visit)(ListIterator&));
void visit(ListIterator&);
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4. Traversals and Iterators
A traversal may be implemented as follows.
void traverse(ListIterator& it,
void (* visit)(ListIterator&)) {
for (it.begin(); !it.atEnd(); ++it)
visit(it);
return; }
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5. Example: Print the List
Define a visiting function print().
Use print() to print (visit) the members of the List.
void print(ListIterator& it) {
cout << *it << endl;
return; }
ListIterator it(list);
list.traverse(it, print);
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6. The Visiting Function Suppose we made print() a member function.
The program would not compile because the prototype of print() would be
What can be done about this?
void print(List* this, ListIterator& it);
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7. Static Member Functions
A static member function does not have the implicit this parameter.
It may not invoke any non-static member function.
If we make print() a static member function
then it will work.
static void print(ListIterator& it);
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8. Implemention of Reverse Iterators
To construct a reverse iterator for a linked list,
Push NULL onto the stack.
Then push the addresses of the nodes onto a stack.
To increment the reverse list iterator
Pop an address off the stack.
Assign it to the node pointer.
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9. Insertion Sort with Iterators
InsertionSortwIter.cpp
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