Re: [boost] [Foreach] Proposal to simplify using Boost.Foreach with maps

Subject: Re: [boost] [Foreach] Proposal to simplify using Boost.Foreach with maps
From: Christian Schladetsch (christian.schladetsch_at_[hidden])
Date: 2009-09-14 18:13:47

Is there any performance difference between

BOOST_FOREACH_PAIR(K const &key, V &val, map)
{
}

and

BOOST_FOREACH(Map::reference ref, map)
{
}

?

On Tue, Sep 15, 2009 at 7:04 AM, Chris Purcell
<chris.purcell.39_at_[hidden]>wrote:

> 2009/9/14 Markus Werle <numerical.simulation_at_[hidden]>:
> > Chris Purcell <chris.purcell.39 <at> gmail.com> writes:
> >>     std::map<int, int> my_map;
> >>     BOOST_FOREACH_PAIR(int key, int value, my_map)
> >>       std::cout << key << " : " << value << "\n";
> >
> > Can you provide a link to the code?
> > I'd like to test it.
>
> I haven't got a web page to put it, but it's pretty small, so I've put
> it inline sans newlines. It's alpha-quality only.
>
> #define BOOST_FOREACH_PAIR(KEY, VALUE, COL) BOOST_FOREACH_PREAMBLE()
> if (boost::foreach_detail_::auto_any_t BOOST_FOREACH_ID(_foreach_col)
> = BOOST_FOREACH_CONTAIN(COL)) {} else if
> (boost::foreach_detail_::auto_any_t BOOST_FOREACH_ID(_foreach_cur) =
> BOOST_FOREACH_BEGIN(COL)) {} else if
> (boost::foreach_detail_::auto_any_t BOOST_FOREACH_ID(_foreach_end) =
> BOOST_FOREACH_END(COL)) {} else for (bool
> BOOST_FOREACH_ID(_foreach_continue) = true,
> BOOST_FOREACH_ID(_foreach_key_loop) = true;
> BOOST_FOREACH_ID(_foreach_continue) && !BOOST_FOREACH_DONE(COL);
> BOOST_FOREACH_ID(_foreach_continue) ? BOOST_FOREACH_NEXT(COL) :
> (void)0) if
>  (boost::foreach_detail_::set_false(BOOST_FOREACH_ID(_foreach_continue)))
> {} else if
> (boost::foreach_detail_::set_false(BOOST_FOREACH_ID(_foreach_key_loop)))
> {} else for (KEY = BOOST_FOREACH_DEREF(COL).first;
> !BOOST_FOREACH_ID(_foreach_key_loop);
> BOOST_FOREACH_ID(_foreach_key_loop) = true) for (VALUE =
> BOOST_FOREACH_DEREF(COL).second; !BOOST_FOREACH_ID(_foreach_continue);
> BOOST_FOREACH_ID(_foreach_continue) = true)
>
> I don't know if there are any changes to the library on subversion
> trunk; the above works with Boost 1.40.0. Any line breaks have been
> added en-route.
>
> Cheers,
> Chris
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