On Friday, August 12, 2011 13:58 Ellery Newcomer wrote: > On 08/12/2011 03:29 PM, Steven Schveighoffer wrote: > > On Fri, 12 Aug 2011 15:54:53 -0400, Ellery Newcomer > > > > <ellery-newco...@utulsa.edu> wrote: > >> in std.container, the stable* container functions advocate that they > >> do not invalidate the ranges of their containers. What does it mean to > >> invalidate a range? > > > > Say for example, you are iterating a red black tree, and your current > > "front" points at a certain node. Then that node is removed from the > > tree. That range is now invalid, because the node it points to is not > > valid. > > Then there is no way to implement a stable remove from a node based > container?
Removing elements from a node-based container only invalidates ranges if they specifically point to an element which was removed. Whether an iterator is invalidated is more obvious, because it points to a specific element, and as long as it's not the one which was removed, you're fine. For a range, it's not as obvious, because you don't really know how it was implemented internally. However, as long as it's effectively holding the begin and end iterators for the range (which is almost certainly what it has to do), then you know that your rang is fine as long as the first element pointed to and the last elemented pointed to weren't removed. You _do_ have the possible concern that your range doesn't contain the same elements that it did before (if an element was removed from its middle), but the range is still valid. - Jonathan M Davis
