<flat_meow>: Don't do extra work in count(), contains(), and equal_range()
#5994
+141
−45
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…ull iterators for flat_map.
…hint is incorrect (Don't do extra work).
StephanTLavavej
added
performance
…atisfy strict_weak_order
…rs when generic key is not key_type.
StephanTLavavej
approved these changes
Jan 8, 2026
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Please note that there is some ongoing conversation and unanswered questions in #5992, so this is likely not the final state of this PR.
Optimize lookups in non-multi containers:
count()is the same ascontains()when searched key is not genericOptimize
equal_range()when its length is at most one and searched key is not genericDon't construct full key-value iterators in
contains()Delay construction of full key-value iterators in
_Flat_map_base::_Find()Shrink bounds for binary search in
_Flat_map_base::_Emplace_hintIntroduce helper
_Flat_map_base::_Iterator_from_key_iteratorfor simpler conversionkey_container_type::(const_)iterator->flat_map::(const_)iteratorReplace all calls to
_RANGES::lower_boundand similar with_STDversions (see discussion https://discord.com/channels/737189251069771789/832305953562427513/1458509280184369246)Resolves #5992