copy_graph doesn't use graph_traits

[Masahiro Nawata <kamo.tanabota@…>]

copy_graph doesn't use graph_traits internally. Therefore, classes which don't have traversal_category and directed_category, such as std::vector or SGB, are not used as the source graph.

follow code is compile error:

#include <vector>
#include <list>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/vector_as_graph.hpp>
#include <boost/graph/copy.hpp>

int main()
{
	using VectorGraph = std::vector<std::list<int>>;
	auto vgraph = VectorGraph{{1, 2, 3}, {3, 5}, {5}, {4}, {0, 2}, {0}};
	using Graph = boost::adjacency_list<>;
	auto graph = Graph{};
	boost::copy_graph(vgraph, graph
			, boost::vertex_copy([](
					  boost::graph_traits<VectorGraph>::vertex_descriptor
					, boost::graph_traits<Graph>::vertex_descriptor) {})
			. edge_copy([](
					  boost::graph_traits<VectorGraph>::edge_descriptor
					, boost::graph_traits<Graph>::edge_descriptor) {})
	);
}

patch is here

--- /usr/local/include/boost/graph/copy.hpp	2014-03-02 21:44:55.000000000 +0900
+++ copy.hpp	2014-03-02 21:45:05.000000000 +0900
@@ -248,8 +248,8 @@
 
     template <class Graph>
     struct choose_graph_copy {
-      typedef typename Graph::traversal_category Trv;
-      typedef typename Graph::directed_category Dr;
+      typedef typename graph_traits<Graph>::traversal_category Trv;
+      typedef typename graph_traits<Graph>::directed_category Dr;
       enum { algo = 
              (is_convertible<Trv, vertex_list_graph_tag>::value
               && is_convertible<Trv, edge_list_graph_tag>::value)