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   1 #ifndef BORROWED_PTR_DWA20020601_HPP
   2 # define BORROWED_PTR_DWA20020601_HPP
   3 // Copyright David Abrahams 2002.
   4 // Distributed under the Boost Software License, Version 1.0. (See
   5 // accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7
   8 # include <boost/config.hpp>
   9 # include <boost/type.hpp>
  10 # include <boost/mpl/if.hpp>
  11 # include <boost/type_traits/object_traits.hpp>
  12 # include <boost/type_traits/cv_traits.hpp>
  13 # include <boost/python/tag.hpp>
  14
  15 namespace boost { namespace python { namespace detail {
  16
  17 template<class T> class borrowed
  18 {
  19     typedef T type;
  20 };
  21
  22 # ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  23 template<typename T>
  24 struct is_borrowed_ptr
  25 {
  26     BOOST_STATIC_CONSTANT(bool, value = false);
  27 };
  28
  29 #  if !defined(__MWERKS__) || __MWERKS__ > 0x3000
  30 template<typename T>
  31 struct is_borrowed_ptr<borrowed<T>*>
  32 {
  33     BOOST_STATIC_CONSTANT(bool, value = true);
  34 };
  35
  36 template<typename T>
  37 struct is_borrowed_ptr<borrowed<T> const*>
  38 {
  39     BOOST_STATIC_CONSTANT(bool, value = true);
  40 };
  41
  42 template<typename T>
  43 struct is_borrowed_ptr<borrowed<T> volatile*>
  44 {
  45     BOOST_STATIC_CONSTANT(bool, value = true);
  46 };
  47
  48 template<typename T>
  49 struct is_borrowed_ptr<borrowed<T> const volatile*>
  50 {
  51     BOOST_STATIC_CONSTANT(bool, value = true);
  52 };
  53 #  else
  54 template<typename T>
  55 struct is_borrowed
  56 {
  57     BOOST_STATIC_CONSTANT(bool, value = false);
  58 };
  59 template<typename T>
  60 struct is_borrowed<borrowed<T> >
  61 {
  62     BOOST_STATIC_CONSTANT(bool, value = true);
  63 };
  64 template<typename T>
  65 struct is_borrowed_ptr<T*>
  66     : is_borrowed<typename remove_cv<T>::type>
  67 {
  68 };
  69 #  endif
  70
  71 # else // no partial specialization
  72
  73 typedef char (&yes_borrowed_ptr_t)[1];
  74 typedef char (&no_borrowed_ptr_t)[2];
  75
  76 no_borrowed_ptr_t is_borrowed_ptr_test(...);
  77
  78 template <class T>
  79 typename mpl::if_c<
  80     is_pointer<T>::value
  81     , T
  82     , int
  83     >::type
  84 is_borrowed_ptr_test1(boost::type<T>);
  85
  86 template<typename T>
  87 yes_borrowed_ptr_t is_borrowed_ptr_test(borrowed<T> const volatile*);
  88
  89 template<typename T>
  90 class is_borrowed_ptr
  91 {
  92  public:
  93     BOOST_STATIC_CONSTANT(
  94         bool, value = (
  95             sizeof(detail::is_borrowed_ptr_test(is_borrowed_ptr_test1(boost::type<T>())))
  96             == sizeof(detail::yes_borrowed_ptr_t)));
  97 };
  98
  99 # endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 100
 101 }
 102
 103 template <class T>
 104 inline T* get_managed_object(detail::borrowed<T> const volatile* p, tag_t)
 105 {
 106     return (T*)p;
 107 }
 108
 109 }} // namespace boost::python::detail
 110
 111 #endif // #ifndef BORROWED_PTR_DWA20020601_HPP