On Tue, 2011-05-10 at 12:11 -0700, Cromwell Enage wrote:
Given the above, I get a bit confused about the meaning of methods like inorder_first(). A cursor, as defined above, seems to not mesh with any particular traversal mode. And the increment operators '++' seem to make sense only as 'increment to the next sibling.'
I couldn't find inorder_first() in the tree proposal. Did you mean inorder::begin(), which is a namespace-level algorithm?
I saw it here: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2101.html#tr.hierar... http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2101.html#tr.hierar... It looks like this: cursor inorder_first(); const_cursor inorder_cfirst() const; * Returns: A cursor to the binary_tree's first element in inorder (see [tr.order.iterators], ยง4). Perhaps it means "if you were going to traverse this tree in-order, here is the cursor that points to the first node you would visit in that traversal" I'm a little skeptical that such a thing is necessary. If I want in-order traversal, or breadth-first traversal, or any other particular kind of traversal, I'd use an appropriate iterator for that (which might very well be implemented on top of a cursor).
And yes, it doesn't look like a cursor is meant to be a drop-in replacement for a breadth-first or depth-first iterator, but that both can be defined in terms of cursors.
That is also a semantic that makes sense to me.