Re: [boost] [range][iterator] contiguous iterators

Subject: Re: [boost] [range][iterator] contiguous iterators
From: Stefan Strasser (strasser_at_[hidden])
Date: 2013-03-19 06:03:47

 From [boost-users]:

Am 18.03.2013 16:06, schrieb Jeffrey Lee Hellrung, Jr.:
> On Sat, Mar 16, 2013 at 7:42 AM, Stefan Strasser <strasser_at_[hidden]
>     is there any way to generically determine at compiletime whether an
>     iterator or a boost range refers to contiguous memory?
>
>     is_contiguous<T *>::value == true
>     is_contiguous<vector<T>::iterator>::value == true
>     is_contiguous<std::list<T>::iterator>::value == false
> AFAIK, not presently, but this has been discussed quite a bit in several
> past threads on the Boost developers list.

Then I'd like to suggest this again to the maintainers of Boost.Iterator 
and Boost.Range.

I'd also like to suggest another addition to Boost.Range:
a RangeOutputIterator, i.e. an OutputIterator that doesn't only accept 
single values, but assignment of ranges:

template<class RangeOutputIterator> ... (...RangeOutputIterator out){
    *out=range;

where range can be any Boost.Range. You can find an implementation of 
this concept here, in the form of an back insert iterator that can 
insert entire ranges into a vector: http://pastebin.com/9M5rPDh9

Using these two things together can make generic algorithms as efficient 
as is possible, e.g. if the container that is being written to is a 
vector and the value type is a POD, there's one call to std::memcpy.
think e.g. about file or database operations like 
database.get(1024*1024,out);

This is in my "namespace detail" right now and I'd be willing to help 
make it public and document it.

Stefan