Hi,
I'm cross-posting here after a kind invitation from Joel.
I hope I can tap into your expert wisom! :-)
I have a fusion sequence of std::vectors which can be specified variably
by users:
typedef boost::fusion::vector Inputs;
Using boost::zip_iterator, I would like to parallel iterate each
std::vector of the sequence and call a user function, but I am not sure
how to proceed. Of course I would like to do this in a generic manner so
that the user can change the number of inputs (std::vectors) at will.
My first non generic shot looks like this:
typedef boost::fusion::vector
Inputs;
Inputs my_input;
struct UserFunction
{
static void apply(int i, int j) { }
}
template<class F>
struct zip_func
{
void operator() (const boost::tuple& t) const
{
F::apply(t.get<0>(), t.get<1>());
}
};
int main (int argc, char* argv[])
{
using namespace boost::fusion;
std::foreach(
boost::make_zip_iterator(
boost::make_tuple(
at_c<0>(my_input).begin(),
at_c<1>(my_input).begin()),
boost::make_zip_iterator(
boost::make_tuple(
at_c<0>(my_input).end(),
at_c<1>(my_input).end()),
zip_func<UserFunction>())
);
}
To the experts on the list:
I don't see how to generalize the zip_func operator() and make_tuple
call based on the fusion::vector signature. Is it even feasible, or is
my intuition leading me in a dead end? I saw that there is a
zip_iterator for fusion sequence in a svn branch
(http://svn.boost.org/svn/boost/branches/zip_iterator_fusion/), should I
go more in that direction? Any pointers would be appreciated.
Thank you for your time,
David.
