Re: [Boost-users] [geometry] problems with the ring concept

Subject: Re: [Boost-users] [geometry] problems with the ring concept
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2013-08-25 08:37:45

Just an observation:

On Sat, Aug 24, 2013 at 11:07 AM, Lepere Renaud <lepere.renaud_at_[hidden]> wrote:
>
>  I have an existing geometric structure, and i try to make it usable with
> boost geometry.  I read the documentation for a similar problem but i did
> not success
> http://www.boost.org/doc/libs/1_54_0/libs/geometry/doc/html/geometry/examples/example__adapting_a_legacy_geometry_object_model.html
>
> My Ring structure is very simple :
> typedef std::vector< Point > Points;
> struct Ring
> {
>     Points points;
> };

I'm not sure you're making it more complex than it needs to be. It
seems like a Ring *IS* a Vector of Points. And/or the *application* of
that type. So why not run with the type you've already defined?

typedef std::vector<Point> points_vector;
//...
points_vector my_ring;

Or:

typedefin std::vector<Point> ring_type;

Then you don't have to implement anything else, no other iterators:
vector is already done for you.

Good luck!

> void f()
> {
>     boost::geometry::concept::check< Geom::Ring >();
> }
> show failure since apparently my range does not support a clear() method
> correctly.
>
> however i think i implemented correctly the range adaption
>
> namespace boost/geometry/traints
> template<> struct tag< Geom::Ring > { typedef ring_tag type; };
>
> namespace Geom
> inline Geom::Points::iterator
> range_begin(Ring & ring) { return ring.points.begin(); }
>
> inline Geom::Points::iterator
> range_end(Ring & ring) { return ring.points.end(); }
>
> inline Geom::Points::const_iterator
> range_begin(const Ring & ring) { return ring.points.begin(); }
>
> inline Geom::Points::const_iterator
> range_end(const Ring & ring) { return ring.points.end(); }
>
> and in namespace  boost
>     template <>
>     struct range_mutable_iterator< Geom::Ring >
>     { typedef Geom::Points::iterator type; };
>     // i tried also with range_iterator
>
>     template<>
>     struct range_const_iterator< Geom::Ring >
>     { typedef Geom::Points::const_iterator type; };
>
> I am a bit lost. Did i missed something obvious ?
> Thanks,
>
> Renaud
>
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