ceph/src/boost/libs/python/include/boost/python/default_call_policies.hpp

   1 // Copyright David Abrahams 2002.
   2 // Distributed under the Boost Software License, Version 1.0. (See
   3 // accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5 #ifndef DEFAULT_CALL_POLICIES_DWA2002131_HPP
   6 # define DEFAULT_CALL_POLICIES_DWA2002131_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9 # include <boost/mpl/if.hpp>
  10 # include <boost/python/to_python_value.hpp>
  11 # include <boost/python/detail/value_arg.hpp>
  12 # include <boost/type_traits/transform_traits.hpp>
  13 # include <boost/type_traits/is_pointer.hpp>
  14 # include <boost/type_traits/is_reference.hpp>
  15 # include <boost/mpl/or.hpp>
  16 # include <boost/mpl/front.hpp>
  17
  18 namespace boost { namespace python {
  19
  20 template <class T> struct to_python_value;
  21
  22 namespace detail
  23 {
  24 // for "readable" error messages
  25   template <class T> struct specify_a_return_value_policy_to_wrap_functions_returning
  26 # if defined(__GNUC__) || defined(__EDG__)
  27   {}
  28 # endif
  29   ;
  30 }
  31
  32 struct default_result_converter;
  33
  34 struct default_call_policies
  35 {
  36     // Ownership of this argument tuple will ultimately be adopted by
  37     // the caller.
  38     template <class ArgumentPackage>
  39     static bool precall(ArgumentPackage const&)
  40     {
  41         return true;
  42     }
  43
  44     // Pass the result through
  45     template <class ArgumentPackage>
  46     static PyObject* postcall(ArgumentPackage const&, PyObject* result)
  47     {
  48         return result;
  49     }
  50
  51     typedef default_result_converter result_converter;
  52     typedef PyObject* argument_package;
  53
  54     template <class Sig>
  55     struct extract_return_type : mpl::front<Sig>
  56     {
  57     };
  58
  59 };
  60
  61 struct default_result_converter
  62 {
  63     template <class R>
  64     struct apply
  65     {
  66         typedef typename mpl::if_<
  67             mpl::or_<is_pointer<R>, is_reference<R> >
  68           , detail::specify_a_return_value_policy_to_wrap_functions_returning<R>
  69           , boost::python::to_python_value<
  70                 typename detail::value_arg<R>::type
  71             >
  72         >::type type;
  73     };
  74 };
  75
  76 // Exceptions for c strings an PyObject*s
  77 template <>
  78 struct default_result_converter::apply<char const*>
  79 {
  80     typedef boost::python::to_python_value<char const*const&> type;
  81 };
  82
  83 template <>
  84 struct default_result_converter::apply<PyObject*>
  85 {
  86     typedef boost::python::to_python_value<PyObject*const&> type;
  87 };
  88
  89 }} // namespace boost::python
  90
  91 #endif // DEFAULT_CALL_POLICIES_DWA2002131_HPP