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mimic what is done for Has_clear 

typeof is an gcc extension
This commit is contained in:
Sébastien Loriot 2016-12-29 10:25:11 +01:00 committed by Laurent Rineau
parent 1b8b63c485
commit 81f4714b1b
1 changed files with 19 additions and 8 deletions
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27
BGL/include/CGAL/boost/graph/split_graph_into_polylines.h
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@ -39,16 +39,26 @@ struct IsTerminalDefault
}
};
template <typename T>
class BGL_sgip_visitor_has_add_edge {
typedef char yes;
struct no { char t[2]; };
template<class T, class ED>
class BGL_sgip_visitor_has_add_edge
{
private:
template<class U, U>
class check {};
template <typename C> static yes test( typeof(&C::add_edge) );
template <typename C> static no test(...);
template<class C>
static char f(check<void(C::*)(ED), &C::add_edge>*);
template<class C>
static char f(check<void(C::*)(const ED&), &C::add_edge>*);
template<class C>
static char f(check<void(C::*)(ED&), &C::add_edge>*);
template<class C>
static int f(...);
public:
enum { value = sizeof(test<T>(0)) == sizeof(yes) };
static const bool value = (sizeof(f<T>(0)) == sizeof(char));
};
template <typename Visitor, typename Edge_descriptor>
@ -57,6 +67,7 @@ bgl_sgip_maybe_call_visitor_add_edge_impl(Visitor&,
Edge_descriptor,
CGAL::Tag_false /*has_add_edge*/)
{
}
template <typename Visitor, typename Edge_descriptor>
@ -71,7 +82,7 @@ bgl_sgip_maybe_call_visitor_add_edge_impl(Visitor& visitor,
template <typename Visitor, typename Edge_descriptor>
void bgl_sgip_maybe_call_visitor_add_edge(Visitor& visitor,
Edge_descriptor e) {
typedef BGL_sgip_visitor_has_add_edge<Visitor> Has_add_edge;
typedef BGL_sgip_visitor_has_add_edge<Visitor, Edge_descriptor> Has_add_edge;
bgl_sgip_maybe_call_visitor_add_edge_impl
( visitor, e, CGAL::Boolean_tag<Has_add_edge::value>() );
}