Re: [Boost-users] [multi_index] iterating over keys and "extracting" key extractors

Subject: Re: [Boost-users] [multi_index] iterating over keys and "extracting" key extractors
From: Joaquin M Lopez Munoz (joaquin_at_[hidden])
Date: 2015-03-18 15:45:29

Nick Stokes <randomaccessiterator <at> gmail.com> writes:

> 
> Q1: Â Is there a builtin in way in MI to iterate over keys rather
> than elements? I.e. the iterator's value type will be that of the
> key, not the element. 

No, there's none. Some iterator adaption is needed as you mention
below.
 
> Q2: Â Is there a way to obtain the type of key extractors given a
> multi index container? Â (it is related to Q1, as this sort of a
> thing could be passed to boost::transform iterator to obtain an
> alternative answer for Q1)

  auto beg=boost::make_transform_iterator(
             foos.get<1>().begin(),foos.get<1>().key_extractor()),
       end=boost::make_transform_iterator(
             foos.get<1>().end(),foos.get<1>().key_extractor());
             
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