ceph/src/boost/libs/python/include/boost/python/object/make_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 MAKE_INSTANCE_DWA200296_HPP
   6 # define MAKE_INSTANCE_DWA200296_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9 # include <boost/python/object/instance.hpp>
  10 # include <boost/python/converter/registered.hpp>
  11 # include <boost/python/detail/decref_guard.hpp>
  12 # include <boost/python/detail/none.hpp>
  13 # include <boost/mpl/assert.hpp>
  14 # include <boost/mpl/or.hpp>
  15 # include <boost/type_traits/is_union.hpp>
  16
  17 namespace boost { namespace python { namespace objects {
  18
  19 template <class T, class Holder, class Derived>
  20 struct make_instance_impl
  21 {
  22     typedef objects::instance<Holder> instance_t;
  23
  24     template <class Arg>
  25     static inline PyObject* execute(Arg& x)
  26     {
  27         BOOST_MPL_ASSERT((mpl::or_<is_class<T>, is_union<T> >));
  28
  29         PyTypeObject* type = Derived::get_class_object(x);
  30
  31         if (type == 0)
  32             return python::detail::none();
  33
  34         PyObject* raw_result = type->tp_alloc(
  35             type, objects::additional_instance_size<Holder>::value);
  36
  37         if (raw_result != 0)
  38         {
  39             python::detail::decref_guard protect(raw_result);
  40
  41             instance_t* instance = (instance_t*)raw_result;
  42
  43             // construct the new C++ object and install the pointer
  44             // in the Python object.
  45             Derived::construct(&instance->storage, (PyObject*)instance, x)->install(raw_result);
  46
  47             // Note the position of the internally-stored Holder,
  48             // for the sake of destruction
  49             Py_SIZE(instance) = offsetof(instance_t, storage);
  50
  51             // Release ownership of the python object
  52             protect.cancel();
  53         }
  54         return raw_result;
  55     }
  56 };
  57
  58
  59 template <class T, class Holder>
  60 struct make_instance
  61     : make_instance_impl<T, Holder, make_instance<T,Holder> >
  62 {
  63     template <class U>
  64     static inline PyTypeObject* get_class_object(U&)
  65     {
  66         return converter::registered<T>::converters.get_class_object();
  67     }
  68
  69     static inline Holder* construct(void* storage, PyObject* instance, reference_wrapper<T const> x)
  70     {
  71         return new (storage) Holder(instance, x);
  72     }
  73 };
  74
  75
  76 }}} // namespace boost::python::object
  77
  78 #endif // MAKE_INSTANCE_DWA200296_HPP