python: initial work on wrapping twa_graph::out(n)

* spot/twa/twagraph.hh (out): Do not hide from SWIG.
* spot/graph/graph.hh: Hide stuff that SWIG do not understand.
* wrap/python/spot_impl.i: Add some typemaps and fragment to
iterate over the result of twa_graph::out().

spot/graph/graph.hh

@@ -36,6 +36,7 @@ namespace spot
 
   namespace internal
   {
+#ifndef SWIG
     template <typename Of, typename ...Args>
     struct first_is_base_of
     {
@@ -48,7 +49,7 @@ namespace spot
       static const bool value =
 	std::is_base_of<Of, typename std::decay<Arg1>::type>::value;
     };
-
+#endif
 
     // The boxed_label class stores Data as an attribute called
     // "label" if boxed is true.  It is an empty class if Data is
@@ -62,6 +63,7 @@ namespace spot
       typedef Data data_t;
       Data label;
 
+#ifndef SWIG
       template <typename... Args,
 		typename = typename std::enable_if<
 		  !first_is_base_of<boxed_label, Args...>::value>::type>
@@ -70,6 +72,7 @@ namespace spot
 	: label{std::forward<Args>(args)...}
       {
       }
+#endif
 
       // if Data is a POD type, G++ 4.8.2 wants default values for all
       // label fields unless we define this default constructor here.
@@ -115,6 +118,7 @@ namespace spot
     {
       typedef Data data_t;
 
+#ifndef SWIG
       template <typename... Args,
 		typename = typename std::enable_if<
 		  !first_is_base_of<boxed_label, Args...>::value>::type>
@@ -123,6 +127,7 @@ namespace spot
 	: Data{std::forward<Args>(args)...}
       {
       }
+#endif
 
       // if Data is a POD type, G++ 4.8.2 wants default values for all
       // label fields unless we define this default constructor here.
@@ -155,7 +160,7 @@ namespace spot
       Edge succ = 0; // First outgoing edge (used when iterating)
       Edge succ_tail = 0;	// Last outgoing edge (used for
 				// appending new edges)
-
+#ifndef SWIG
       template <typename... Args,
 		typename = typename std::enable_if<
 		  !first_is_base_of<distate_storage, Args...>::value>::type>
@@ -164,6 +169,7 @@ namespace spot
 	: State_Data{std::forward<Args>(args)...}
       {
       }
+#endif
     };
 
     //////////////////////////////////////////////////
@@ -189,6 +195,7 @@ namespace spot
       {
       }
 
+#ifndef SWIG
       template <typename... Args>
       edge_storage(StateOut dst, Edge next_succ,
 		    StateIn src, Args&&... args)
@@ -199,6 +206,7 @@ namespace spot
 	dst(dst), next_succ(next_succ), src(src)
       {
       }
+#endif
 
       bool operator<(const edge_storage& other) const
       {
@@ -231,12 +239,12 @@ namespace spot
     // of that list.
 
     template <typename Graph>
-    class SPOT_API edge_iterator:
+    class SPOT_API edge_iterator: public
-      std::iterator<std::forward_iterator_tag,
+    std::iterator<std::forward_iterator_tag,
-		    typename
+		  typename
-		    std::conditional<std::is_const<Graph>::value,
+		  std::conditional<std::is_const<Graph>::value,
-				     const typename Graph::edge_storage_t,
+				   const typename Graph::edge_storage_t,
-				     typename Graph::edge_storage_t>::type>
+				   typename Graph::edge_storage_t>::type>
     {
       typedef
 	std::iterator<std::forward_iterator_tag,
@@ -274,12 +282,24 @@ namespace spot
 	return g_->edge_storage(t_);
       }
 
+      const typename super::reference
+      operator*() const
+      {
+	return g_->edge_storage(t_);
+      }
+
       typename super::pointer
       operator->()
       {
 	return &g_->edge_storage(t_);
       }
 
+      const typename super::pointer
+      operator->() const
+      {
+	return &g_->edge_storage(t_);
+      }
+
       edge_iterator operator++()
       {
 	t_ = operator*().next_succ;
@@ -412,7 +432,7 @@ namespace spot
     //////////////////////////////////////////////////
 
     template <typename Graph>
-    class SPOT_API all_edge_iterator:
+    class SPOT_API all_edge_iterator: public
       std::iterator<std::forward_iterator_tag,
 		    typename
 		    std::conditional<std::is_const<Graph>::value,
@@ -484,11 +504,23 @@ namespace spot
 	return tv_[t_];
       }
 
-      typename super::pointer
+      const typename super::reference
+      operator*() const
+      {
+	return tv_[t_];
+      }
+
+      const typename super::pointer
       operator->()
       {
 	return &tv_[t_];
       }
+
+      typename super::pointer
+      operator->() const
+      {
+	return &tv_[t_];
+      }
     };
 
 

spot/twa/twagraph.hh

@@ -387,11 +387,20 @@ namespace spot
     }
 
 #ifndef SWIG
-    auto out(unsigned src) const
+    internal::state_out<const graph_t>
-      SPOT_RETURN(g_.out(src));
+    out(unsigned src) const
-    auto out(unsigned src)
+    {
-      SPOT_RETURN(g_.out(src));
+      return g_.out(src);
+    }
+#endif
 
+    internal::state_out<graph_t>
+    out(unsigned src)
+    {
+      return g_.out(src);
+    }
+
+#ifndef SWIG
     auto states() const
       SPOT_RETURN(g_.states());
     auto states()

wrap/python/spot_impl.i

@@ -109,8 +109,8 @@
 #include <spot/twa/twaproduct.hh>
 
 #include <spot/twaalgos/cleanacc.hh>
-#include <spot/twaalgos/dot.hh>
 #include <spot/twaalgos/degen.hh>
+#include <spot/twaalgos/dot.hh>
 #include <spot/twaalgos/copy.hh>
 #include <spot/twaalgos/complete.hh>
 #include <spot/twaalgos/complement.hh>
@@ -153,6 +153,71 @@ using namespace spot;
 %}
 
 
+// Swig come with iterators that implement a decrement method.
+// This is not supported in our "successor" iterators.
+%fragment("ForwardIterator_T","header",fragment="SwigPyIterator_T") {
+namespace swig
+{
+  template<typename OutIterator,
+	   typename ValueType =
+	   typename std::iterator_traits<OutIterator>::value_type,
+	   typename FromOper = from_oper<ValueType> >
+  class ForwardIterator_T :  public SwigPyIterator_T<OutIterator>
+  {
+  public:
+    FromOper from;
+    typedef OutIterator out_iterator;
+    typedef ValueType value_type;
+    typedef SwigPyIterator_T<out_iterator>  base;
+    typedef ForwardIterator_T<OutIterator, ValueType, FromOper> self_type;
+
+    ForwardIterator_T(out_iterator curr, out_iterator first,
+		      out_iterator last, PyObject *seq)
+      : SwigPyIterator_T<OutIterator>(curr, seq), begin(first), end(last)
+    {
+    }
+
+    PyObject *value() const {
+      if (base::current == end) {
+	throw stop_iteration();
+      } else {
+	return from(static_cast<const value_type&>(*(base::current)));
+      }
+    }
+
+    SwigPyIterator *copy() const
+    {
+      return new self_type(*this);
+    }
+
+    SwigPyIterator *incr(size_t n = 1)
+    {
+      while (n--) {
+	if (base::current == end) {
+	  throw stop_iteration();
+	} else {
+	  ++base::current;
+	}
+      }
+      return this;
+    }
+
+  private:
+    out_iterator begin;
+    out_iterator end;
+  };
+
+  template<typename OutIter>
+  inline SwigPyIterator*
+  make_forward_iterator(const OutIter& current,
+			const OutIter& begin,
+			const OutIter& end, PyObject *seq = 0)
+  {
+    return new ForwardIterator_T<OutIter>(current, begin, end, seq);
+  }
+}
+}
+%fragment("ForwardIterator_T");
 
 // For spot::emptiness_check_instantiator::construct and any other
 // function that return errors via a "char **err" argument.
@@ -284,8 +349,25 @@ namespace std {
 
 %include <spot/twa/taatgba.hh>
 %include <spot/twa/twaproduct.hh>
+
+%include <spot/graph/graph.hh>
+%nodefaultctor spot::digraph;
+%nodefaultctor spot::internal::state_out;
+%traits_swigtype(spot::internal::edge_storage<unsigned int, unsigned int, unsigned int, spot::internal::boxed_label<spot::twa_graph_edge_data, false> >);
+%fragment(SWIG_Traits_frag(spot::internal::edge_storage<unsigned int, unsigned int, unsigned int, spot::internal::boxed_label<spot::twa_graph_edge_data, false> >));
+
+%typemap(out, optimal="1") spot::internal::state_out<spot::digraph<spot::twa_graph_state, spot::twa_graph_edge_data>> {
+  $result = SWIG_NewPointerObj(new $1_ltype($1), $&1_descriptor,
+			       SWIG_POINTER_OWN);
+}
+
+%noexception spot::twa_graph::out;
 %include <spot/twa/twagraph.hh>
 
+%template(twa_graph_state_out) spot::internal::state_out<spot::digraph<spot::twa_graph_state, spot::twa_graph_edge_data>>;
+%template(twa_graph_edge_boxed_data) spot::internal::boxed_label<spot::twa_graph_edge_data, false>;
+%template(twa_graph_edge_storage) spot::internal::edge_storage<unsigned int, unsigned int, unsigned int, spot::internal::boxed_label<spot::twa_graph_edge_data, false> >;
+
 // Should come after the definition of twa_graph
 
 %include <spot/twaalgos/cleanacc.hh>
@@ -303,8 +385,8 @@ namespace std {
 %include <spot/twaalgos/magic.hh>
 %include <spot/twaalgos/minimize.hh>
 %include <spot/twaalgos/neverclaim.hh>
-%include <spot/twaalgos/strength.hh>
 %include <spot/twaalgos/remfin.hh>
+%include <spot/twaalgos/strength.hh>
 %include <spot/twaalgos/sccfilter.hh>
 %include <spot/twaalgos/stats.hh>
 %include <spot/twaalgos/isdet.hh>
@@ -369,6 +451,15 @@ namespace std {
   }
 }
 
+
+%extend spot::internal::state_out<spot::digraph<spot::twa_graph_state, spot::twa_graph_edge_data>> {
+  swig::SwigPyIterator* __iter__(PyObject **PYTHON_SELF)
+   {
+      return swig::make_forward_iterator(self->begin(), self->begin(),
+				         self->end(), *PYTHON_SELF);
+   }
+}
+
 %extend spot::acc_cond::acc_code {
   std::string __repr__()
   {