[boost] Re: BGL: edge_descriptor

From: Alexey Nikitin (reductor_at_[hidden])
Date: 2003-09-29 02:10:29

Sorry for my bad English...

> Two options come to mind:
>   1) Add an internal edge_index property to your edges, and use an
> std::map<std::Size_t, edge_descriptor>, or
Thanks, it works.

>   2) Just make your map into an edge property. That'll give you O(1)
> access instead of O(lg n) access.
This method looks very prettily, but next code not compiled:

#define _DEBUG
#include <cassert>
#include <utility>
#include <boost/graph/adjacency_list.hpp>
using namespace boost;
using namespace std;

struct EDescr;
struct edge_descr_t { typedef edge_property_tag kind; };
typedef property<edge_descr_t, EDescr> EDescrProp;
typedef adjacency_list<vecS, vecS, directedS, no_property, EDescrProp>
Graph;
typedef graph_traits<Graph>::edge_descriptor EdgeDescr;

struct EDescr
{
  EDescr() {};
  EDescr(EdgeDescr e) : edge(e) {}
  operator EdgeDescr() const { return edge; }
  operator EdgeDescr&() { return edge; }
  EdgeDescr edge;
};

int main()
{
  Graph g(8);
  pair<EdgeDescr,bool> e0 = add_edge(0, 1, g);
  assert(e0.second);
  pair<EdgeDescr,bool> e1 = add_edge(1, 2, g);
  assert(e1.second);
  put(edge_descr_t(), g, e0.first, e1.first);
  put(edge_descr_t(), g, e1.first, e0.first);
}

with error
... boost\pending\property.hpp(24) : error C2079:
 'boost::property<Tag,T>::m_value' uses undefined struct 'EDescr'
        with
        [
            Tag=edge_descr_t,
            T=EDescr
        ]
and many other. I'm use MSVC 7.1.

Can anybody help me to correct this example?

Thanks, Alexey.