Re: [Boost-users] [graph] Graph type needed in graph proptery, cyclic definition problem, minimal example

Subject: Re: [Boost-users] [graph] Graph type needed in graph proptery, cyclic definition problem, minimal example
From: Christoph (c_p_at_[hidden])
Date: 2011-10-26 16:26:27

ahh now i see, because of the (shared) pointer to the priority_queue the
forward declaration 'struct degree_compare;' works. This is really good
to know.
So this was my missing part. Thank you for your patience!

On Wed, 2011-10-26 at 15:52 -0400, Jeremiah Willcock wrote:
> On Wed, 26 Oct 2011, Christoph wrote:
> 
> > i am sorry but i can't find the solution to my problem. I know how to
> > use
> >
> > boost::adjacency_list_traits<boost::listS, boost::vecS,
> > boost::bidirectionalS>::vertex_descriptor
> >
> > and
> >
> > boost::adjacency_list_traits<boost::listS, boost::vecS,
> > boost::bidirectionalS>::edge_descriptor
> >
> > inside of bundled graph properties but i need the graph type itself to
> > use 'vertex_degree (u, g)' in the comparison object given to a
> > priority_queue inside of the graph_property struct (see first example).
> 
> Is having a shared_ptr (or scoped_ptr) to the priority_queue acceptable to 
> have in your graph property?  If so, I have it working:
> 
> // begin code
> 
> #include <iostream>
> #include <map>
> #include <queue>
> #include <boost/graph/adjacency_list.hpp>
> #include <boost/smart_ptr.hpp>
> 
> typedef boost::adjacency_list_traits<boost::listS, boost::vecS,
> boost::bidirectionalS>
> link_adjacency_list_traits;
> 
> struct vertex_properties;
> struct edge_properties;
> struct graph_properties;
> 
> struct vertex_properties {
>          std::map <int, link_adjacency_list_traits::edge_descriptor >
> used_colors;
>          // this one works fine, i can use a traits::edge_descriptor
> };
> 
> struct degree_compare;
> 
> struct graph_properties {
>          int delta;
>          boost::shared_ptr<
>            std::priority_queue<
>              link_adjacency_list_traits::vertex_descriptor,
>              std::vector<link_adjacency_list_traits::vertex_descriptor>,
>              degree_compare> > pq;
>          // link_adjacency_list_traits::??? g;
>          // i need a 'traits_graph', too
>          // link_graph g; is not possible because its definition needs
>          // the definition of graph_properties
>          // how to declare it?
>          // but out_degree (u, g) does not need to know any properties
> };
> 
> struct edge_properties {
>          int color;
> };
> 
> typedef boost::adjacency_list < boost::listS,
>                          boost::listS,
>                          boost::bidirectionalS,
>                          vertex_properties,
>                          edge_properties,
>                          graph_properties>
> link_graph;
> 
> struct degree_compare {
>    const link_graph& g;
>    degree_compare(const link_graph& g): g(g) {}
>    bool operator()(const 
> boost::graph_traits<link_graph>::vertex_descriptor& a,
>                    const 
> boost::graph_traits<link_graph>::vertex_descriptor& b) const {
>      return out_degree(a, g) < out_degree(b, g);
>    }
> };
> 
> int main ()
> {
>          link_graph g;
> }
> 
> // end code
> 
> 
> -- Jeremiah Willcock
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-- 
Christoph <c_p_at_[hidden]>