Please consider proposing btree to C++17

[GoogleCodeExporter]

btree_map and btree_set are both extremely useful. They beat STL 
unordered/map/set both in insertion time, lookup time and space consumption so 
it would be a very valuable addition. 

Many people from industry are not happy with STL associative containers and 
they usually create their own (see recent CppCon video 
https://www.youtube.com/watch?v=rX0ItVEVjHc. Also famous paper from committee 
member: http://lafstern.org/matt/col1.pdf)

Also consider changing the lookup interface along heterogeneous lookup proposal 
(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3657.htm) when 
available. There are too many std::string/QString/CString keys out there (see 
one sad story here: 
http://channel9.msdn.com/Shows/C9-GoingNative/GoingNative-29-Massive-Improvement
s-for-Browsing-in-Large-Codebases-)

Common google you can do it

Original issue reported on code.google.com by pecholt@gmail.com on 8 Oct 2014 at 11:25