Howard Hinnant 397717b7c8 constexpr applied to <array>. ... llvm-svn: 160564		2012-07-20 19:20:49 +00:00
..
associative	The rules for emplace in map, multimap, unordered_map and unordered_multimap changed a while back and I'm just now updating to these new rules. In a nutshell, you've got to know you're emplacing to a pair and use one of pair's constructors. I made one extension: If you want to emplace the key and default construct the mapped_type, you can just emplace(key), as opposed to emplace(piecewise_construct, forward_as_tuple(key), forward_as_tuple()).	2012-05-25 22:04:21 +00:00
container.adaptors	noexcept for <stack>. This completes noexcept for Chapter 23 [containers].	2011-06-04 22:09:19 +00:00
container.requirements	license change	2010-11-16 22:09:02 +00:00
containers.general	license change	2010-11-16 22:09:02 +00:00
sequences	constexpr applied to <array>.	2012-07-20 19:20:49 +00:00
unord	This commit establishes a new bucket_count policy in the unordered containers: The policy now allows a power-of-2 number of buckets to be requested (and that request honored) by the client. And if the number of buckets is set to a power of 2, then the constraint of the hash to the number of buckets uses & instead of %. If the client does not specify a number of buckets, then the policy remains unchanged: a prime number of buckets is selected. The growth policy is that the number of buckets is roughly doubled when needed. While growing, either the prime, or the power-of-2 strategy will be preserved. There is a small run time cost for putting in this switch. For very cheap hash functions, e.g. identity for int, the cost can be as high as 18%. However with more typical use cases, e.g. strings, the cost is in the noise level. I've measured cases with very cheap hash functions (int) that using a power-of-2 number of buckets can make look up about twice as fast. However I've also noted that a power-of-2 number of buckets is more susceptible to accidental catastrophic collisions. Though I've also noted that accidental catastrophic collisions are also possible when using a prime number of buckets (but seems far less likely). In short, this patch adds an extra tuning knob for those clients trying to get the last bit of performance squeezed out of their hash containers. Casual users of the hash containers will not notice the introduction of this tuning knob. Those clients who swear by power-of-2 hash containers can now opt-in to that strategy. Clients who prefer a prime number of buckets can continue as they have.	2012-07-06 17:31:14 +00:00
Copyable.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
DefaultOnly.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
Emplaceable.h	Suppress some warings in the tests.	2011-05-13 23:59:50 +00:00
MoveOnly.h	Changed __config to react to all of clang's currently documented has_feature flags, and renamed _LIBCPP_MOVE to _LIBCPP_HAS_NO_RVALUE_REFERENCES to be more consistent with the rest of the libc++'s flags, and with clang's nomenclature.	2010-09-04 23:28:19 +00:00
NotConstructible.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
iterators.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
nothing_to_do.pass.cpp	license change	2010-11-16 22:09:02 +00:00
stack_allocator.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
test_allocator.h	Changed __config to react to all of clang's currently documented has_feature flags, and renamed _LIBCPP_MOVE to _LIBCPP_HAS_NO_RVALUE_REFERENCES to be more consistent with the rest of the libc++'s flags, and with clang's nomenclature.	2010-09-04 23:28:19 +00:00
test_compare.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00
test_hash.h	Fixing whitespace problems	2010-08-22 00:15:28 +00:00