Geometry Boost List: Re: [geometry] Using iterator_range as a Geometry

Subject: Re: [geometry] Using iterator_range as a Geometry
From: Sakari Bergen (sakari.bergen_at_[hidden])
Date: 2012-05-25 13:39:42

Ok, now I just feel stupid :P

BOOST_GEOMETRY_REGISTER_LINESTRING_TEMPLATED(boost::iterator_range);
seems to do the trick. I thought I tried that already, but I must have done
something else wrong since I didn't get it to work with my code...

Thanks for the hint, now I can get rid of that ugly piece of coding!

-Sakari-

On Fri, May 25, 2012 at 5:01 PM, feverzsj <feverzsj_at_[hidden]> wrote:

> hi, Sakari
>
>
> Sakari Bergen wrote
> >
> > Hello,
> >
> > First of all I'd like to note that I am fairly new to both Boost.Geometry
> > and Boost.Range, so I might be doing something non-optimal here.
> >
> > I'm using two boost::circular_buffers to store "events" (time stamps and
> > points), one containing the time stamps and the other the points. I need
> > to
> > make linestrings out of a subset of the points, and currently I'm using
> > iterator_range to achieve this in an efficient manner. However, the
> > problem
> > I'm facing (which I did solve, a code snippet will follow) is that the
> > linestring template assumes that all containers take two template
> > parameters, the type and the allocator, where as iterator_range uses the
> > iterator type as it's only template parameter.
> >
> > I solved the issue by making an adapter class template, which takes the
> > correct template parameters (the second one being unused), and provides
> > the
> > appropriate two iterator constructor so that it can be used with
> > linestring. I wrapped all of this in macros and typedefs to make it more
> > generic and easier to use.
> >
> > I was wondering if there is an easier way to do this, or if the library
> > could be modified in some way to make it easier?
> >
> > -Sakari-
> >
> > Here's the code:
> >
> > -----------------------
> >
> > // Iterator range adapter for boost::geometry stuff
> > // (which expects containers to have two template parameters: T and
> > Allocator)
> > #define ITERATOR_RANGE_ADAPTER(ClassName, ContainerType, IteratorType) \
> > template<typename T, typename Unused> \
> > class ClassName \
> >         : public boost::iterator_range<typename
> > ContainerType<T>::IteratorType> \
> > { \
> >         typedef typename ContainerType<T>::IteratorType iterator_; \
> >         typedef boost::iterator_range<iterator_> base_class_; \
> > public: \
> >         ClassName(iterator_ b, iterator_ e) : base_class_(b, e) {} \
> > };
> >
> > // Uses the above to adapt a iterator range to a line string
> > #define ITERATOR_RANGE_GEOMETRY_TYPEDEF(TypedefName, GeometryType,
> > PointType, ContainerType, IteratorType) \
> > ITERATOR_RANGE_ADAPTER(TypedefName##Adapter, ContainerType, IteratorType)
> > \
> > typedef GeometryType<PointType, TypedefName##Adapter> TypedefName;
> >
> > -----------------------
> >
> > After which I can do (Point3D is a typedef for a geometry::point):
> >
> > ITERATOR_RANGE_GEOMETRY_TYPEDEF(RangeLinestring,
> > boost::geometry::model::linestring, Point3D, boost::circular_buffer,
> > const_iterator)
> > RangeLinestring rls(some_cb_iterator, other_cb_iterator);
> >
> > _______________________________________________
> > Geometry mailing list
> > Geometry_at_.boost
> > http://lists.boost.org/mailman/listinfo.cgi/geometry
> >
>
>
> a dirty and quick way, just as a hint
>
> // this will register any iterator_range<> as ggl linestring
>
> namespace boost{ namespace geometry{ namespace traits{
>
> template<class Iter>
> struct tag<iterator_range<Iter> >
> {
>    typedef linestring_tag type;
> };
>
> }}}
>
> regards, zsj
>
> --
> View this message in context:
> http://boost-geometry.203548.n3.nabble.com/Using-iterator-range-as-a-Geometry-tp4015187p4015268.html
> Sent from the Boost Geometry mailing list archive at Nabble.com.
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