boost/python/object/instance.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 INSTANCE_DWA200295_HPP
   6 # define INSTANCE_DWA200295_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9 # include <boost/type_traits/alignment_traits.hpp>
  10 # include <cstddef>
  11
  12 namespace boost { namespace python
  13 {
  14   struct instance_holder;
  15 }} // namespace boost::python
  16
  17 namespace boost { namespace python { namespace objects {
  18
  19 // Each extension instance will be one of these
  20 template <class Data = char>
  21 struct instance
  22 {
  23     PyObject_VAR_HEAD
  24     PyObject* dict;
  25     PyObject* weakrefs;
  26     instance_holder* objects;
  27
  28     typedef typename type_with_alignment<
  29         ::boost::alignment_of<Data>::value
  30     >::type align_t;
  31
  32     union
  33     {
  34         align_t align;
  35         char bytes[sizeof(Data)];
  36     } storage;
  37 };
  38
  39 template <class Data>
  40 struct additional_instance_size
  41 {
  42     typedef instance<Data> instance_data;
  43     typedef instance<char> instance_char;
  44     BOOST_STATIC_CONSTANT(
  45         std::size_t, value = sizeof(instance_data)
  46                            - BOOST_PYTHON_OFFSETOF(instance_char,storage));
  47 };
  48
  49 }}} // namespace boost::python::object
  50
  51 #endif // INSTANCE_DWA200295_HPP