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Subject: Re: [boost] [range] fat iterators?
From: Daniel James (daniel_at_[hidden])
Date: 2013-11-12 13:44:02

On 12 November 2013 17:13, Eric Niebler <eniebler_at_[hidden]> wrote:
> On 11/12/2013 8:21 AM, Evgeny Panasyuk wrote:
>> 12.11.2013 19:41, Eric Niebler:
>>> I've now built a filter_range, transform_range, and an
>>> istream_range in this vein. Initial results are looking promising,
>>> but I haven't benchmarked performance, yet. A commenter on my blog
>>> claims to have benchmarked perf of istream_range, with good
>>> results, which is encouraging.
>> While new "slim" istream_range is faster than version with "fat"
>> iterators, it is still not the fastest possible. In particular, it
>> does two comparisons per cycle iteration: one is "!rng_->next()", and
>> another is comparison of iterators, like "it != last".
> <snip>
> The commenter on my blog claims this extra check is optimized away by a
> smart compiler like gcc. He says[^1]:

Regardless of efficiency, a range adaptor could make implementing
input and forward ranges much easier.

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