Constructor
Reference key. May be changed at any time but becomes effective on the next iteration start.
Set to true to skip key duplicates. This flag may be changed during iteration.
foreach iterator over nodes in the tree. Any tree modification is permitted during iteration.
foreach_reverse iterator over nodes in the tree. Any tree modification is permitted during iteration.
Provides 'foreach' and 'foreach_reverse' iteration over the nodes in the tree, starting with the first node whose key is greater or less than a reference key, respectively.