Re: [boost] Review managers wanted for augmented data structures

on Mon Mar 04 2013, Vadim Stadnik wrote:

On Mon, Mar 4, 2013 at 7:35 PM, Stefan Strasser wrote:

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Am 04.03.2013 08:48, schrieb Martin Knoblauch Revuelta:

Do you mean that you would declare them RandomAccess iterators?

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We can expect to have containers with millions of elements. For that size, O(log N) is about 20 times faster than O(log N log N). That makes a big difference.

isn't that a reason for providing optimized specializations of some STL algorithms, instead of introducing another iterator category?

how would a new iterator category even help? as long as your iterator is a forward iterator, the user is allowed to call std::binary_search on your iterator, which uses the same algorithm on any iterator category. (only functions used by binary_search like std::advance are specialized on the category) where in all this would your tree-optimized binary_search code be called?

the standard doesn't require random access iterator ops to be constant time.

Unfortunately, there is a problem of iterator categories with augmented trees. The C++ standard specifies computational complexity for iterator operations, although they are not shown in tables, since all of them are required to be constant time. In both C++03 and C++11 this is formulated in the section 24.1.8.

Are you sure these iterators don't fall under the *amortized* constant time requirements, just like those of the ordered associative containers? -- Dave Abrahams