[Boost-users] [Boost : icpc assignment operator compiler error with boost filter_iterator and filtered_graph

Subject: [Boost-users] [Boost : icpc assignment operator compiler error with boost filter_iterator and filtered_graph
From: Aniket Pugaonkar (aniket.pugaonkar_at_[hidden])
Date: 2014-06-25 20:46:27

Hello,

I have  the following filter iterator working perfectly with gcc 4.7 and
4.9 as well (C++11 support)
But when I compile my code with intel compiler 13.0.1 version I get the
following error

error: *implicitly generated assignment operator cannot copy: reference
member* "my_func::G"
  ...

Details:
I am using a filtered_graph over Boost::adjacency_list as my graph type
(Graph_t). The vertex_iterator  (from graph_traits<Graph_t> .. provides
iterator range to iterate over graph vertices. I have to assign each graph
vertex an id (using property_maps) and group them together by applying
filter_iterator over
vertex iterator.

example: suppose I want to create 4 subgroups of vertices. So I create a
filter predicate which is passed to filter iterator which gives me
iterators <fbegin, fend> satisfying the predicate.
For FOUR such groups, I get 4 pairs of filter iterators.
A vector stores such filter_iterator pairs.

std::vector <  pair <filter_iterator_t, filter_iterator_t> >  my_vector
//stores iterator pair.

Here is the code:

  vertex_iterator  vbegin, vend;
  boost::tie(vbegin, vend) = boost::vertices(G);

  for (int i=0; i<4; ++i)
  {
    //for each i, create a filter_pred object
    my_filter_pred <Graph>  filter_pred(G, i)

    //now create begin and end filter iterators as follows
    auto fbegin = boost::make_filter_iterator< my_filter_pred<Graph>,
                                       vertex_iterator>
(filter_pred, vbegin, vend)
    auto fend = boost::make_filter_iterator< my_filter_pred<Graph>,
                                       vertex_iterator>
(filter_pred, vend, vend)

    //fbegin, fend are of type filter iterator
    //insert the iterator pair into vector
    my_vector.push_back( std::make_pair (fbegin, fend) );
   }

The predicate is below :

 template<typename Graph>
 struct my_filter_pred {
   public:
     my_filter_pred() { }
     my_filter_pred(Graph& _G, int _value) : G(_G), value(_value) {  }

     template<typename vertex_t>
     bool operator() (vertex_t vertex) {

        //get property "p" of vertex in graph G
        auto p = get (mypropertytype, vertex, G);
        return (p.val == value);
     }

     private:
      Graph& G;
    }

ERROR :

   error: implicitly generated assignment operator cannot copy:
        reference member "my_filter_pred <Graph>::G [with ... ]"

I tried to provide my own assignment operator as below:

my_filter_pred&  operator=(const my_filter_pred& other) {
   if (this != &other)
     G = other.G;
   return *this;

}

But it gave the same  icpc error for  actual typedef graph which is below
:

 error: implicitly generated assignment operator cannot copy:
" implicit generation of boost::filtered_graph_base<Graph_t> " ....

Please help what should I do in this case to work.

main motive : is to have a container which stores <iterator, iterator>
pair  which satisfies a predicate. Filter iterator was the best choice i
could have to apply different filter predicate to same vertex_iterator
range vbegin, vend;

Thanks
Aniket Pugaonkar

Aniket Pugaonkar