Re: [boost] Heads up - string_ref landing

Subject: Re: [boost] Heads up - string_ref landing
From: Yakov Galka (ybungalobill_at_[hidden])
Date: 2012-11-16 13:34:35

On Fri, Nov 16, 2012 at 8:16 PM, Peter Dimov <lists_at_[hidden]> wrote:

> [...]
>
>> Lastly, and I don't know how big a deal this is, but one could write more
>> tailored range algorithms for contiguous_ranges of POD types (using
>> std::memcpy or std::memset, for example, which may produce more optimal
>> code (?) than std::copy or std::fill, resp.). So I can see a plausible
>> advantage in having a single template class abstracting contiguous ranges.
>>
>
> To do this, you should accept an arbitrary Range and check a trait
> (is_contiguous), not hardcode contiguous_range<> (for instance, std::vector
> isn't contiguous_range<>, bit it is a contiguous range).
>

I would attack this problem in a different way. There should be a
contiguous_iterator_tag : random_access_iterator_tag in the standard, then
we get two things for free:

* Paragraphs ?.2.2/3 are not longer relevant. We will be able to construct
a string_ref from any Range of contiguous_iterators.
* The standard library implementation can specialize the standard
algorithms for std::copy to use the optimized memcpy whenever a
contiguous_iterators to a POD is given.

contiguous_range<> would be essentially an iterator_range<> with
contiguous_iterators.

-- 
Yakov