Looking for std::map::erase_if

[Dimitry Andric]

Well, -std=c++20 even, it is that new. :)

That said, it's always hazardous to rely on experimental features, they are effectively unsupported.

As shown on e.g. cppreference.com, you can use an equivalent function that looks like:

auto old_size = c.size();
for (auto i = c.begin(), last = c.end(); i != last; ) {
  if (pred(*i)) {
    i = c.erase(i);
  } else {
    ++i;
  }
}

-Dimitry

> On 20 Mar 2021, at 16:22, Alan Somers <asomers at FreeBSD.org> wrote:
> 
> I'm just guessing, but I think you should remove the "experimental" and
> build with -std=c++17 .
> -Alan
> 
> On Sat, Mar 20, 2021 at 9:06 AM Willem Jan Withagen <wjw at digiware.nl> wrote:
> 
>> On 20-3-2021 15:46, Alan Somers wrote:
>> 
>> It looks like it's in there.  What code are you trying that doesn't work?
>> 
>> Hi Alan,
>> 
>> I thought so too, but all tries last 2 weeks did not result into anything
>> that got it compiling...
>> But could be that I did not try hard enough, real work is pulling a lot
>> atm.
>> 
>> Code is at:
>> 
>> https://github.com/dillaman/ceph/blob/138d71fb0635682510cadda8e4ad5aaab3f39e44/src/librbd/api/Trash.cc#L299
>> 
>> Thanx,
>> --WjW
>> 
>> 
>>> grep erase_if  /usr/include/c++/v1/map
>>  void erase_if(map<Key, T, Compare, Allocator>& c, Predicate pred);  //
>> C++20
>>  void erase_if(multimap<Key, T, Compare, Allocator>& c, Predicate pred);
>> // C++20
>> void erase_if(map<_Key, _Tp, _Compare, _Allocator>& __c, _Predicate __pred)
>> { __libcpp_erase_if_container(__c, __pred); }
>> void erase_if(multimap<_Key, _Tp, _Compare, _Allocator>& __c, _Predicate
>> __pred)
>> { __libcpp_erase_if_container(__c, __pred); }
>> 
>> On Sat, Mar 20, 2021 at 8:39 AM Willem Jan Withagen via freebsd-hackers <
>> freebsd-hackers at freebsd.org> wrote:
>> 
>>> Hi,
>>> 
>>> [ Trying this on FBSD 12.2 ]
>>> 
>>> In the Ceph code new code uses std::map::erase_if.
>>> Which is in Linux imported from <experimental/map>
>>> 
>>> Anybody suggestions on libraries to get something matching??
>>> 
>>> Thanx,
>>> --WjW
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>>> 
>> 
>> 
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