boost/random/detail/ptr_helper.hpp

   1 /* boost random/detail/ptr_helper.hpp header file
   2  *
   3  * Copyright Jens Maurer 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  * See http://www.boost.org for most recent version including documentation.
   9  *
  10  * $Id: ptr_helper.hpp 24096 2004-07-27 03:43:34Z dgregor $
  11  *
  12  */
  13
  14 #ifndef BOOST_RANDOM_DETAIL_PTR_HELPER_HPP
  15 #define BOOST_RANDOM_DETAIL_PTR_HELPER_HPP
  16
  17 #include <boost/config.hpp>
  18
  19
  20 namespace boost {
  21 namespace random {
  22 namespace detail {
  23
  24 // type_traits could help here, but I don't want to depend on type_traits.
  25 template<class T>
  26 struct ptr_helper
  27 {
  28   typedef T value_type;
  29   typedef T& reference_type;
  30   typedef const T& rvalue_type;
  31   static reference_type ref(T& r) { return r; }
  32   static const T& ref(const T& r) { return r; }
  33 };
  34
  35 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  36 template<class T>
  37 struct ptr_helper<T&>
  38 {
  39   typedef T value_type;
  40   typedef T& reference_type;
  41   typedef T& rvalue_type;
  42   static reference_type ref(T& r) { return r; }
  43   static const T& ref(const T& r) { return r; }
  44 };
  45
  46 template<class T>
  47 struct ptr_helper<T*>
  48 {
  49   typedef T value_type;
  50   typedef T& reference_type;
  51   typedef T* rvalue_type;
  52   static reference_type ref(T * p) { return *p; }
  53   static const T& ref(const T * p) { return *p; }
  54 };
  55 #endif
  56
  57 } // namespace detail
  58 } // namespace random
  59 } // namespace boost
  60
  61 //
  62 // BOOST_RANDOM_PTR_HELPER_SPEC --
  63 //
  64 //  Helper macro for broken compilers defines specializations of
  65 //  ptr_helper.
  66 //
  67 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  68 # define BOOST_RANDOM_PTR_HELPER_SPEC(T)                \
  69 namespace boost { namespace random { namespace detail { \
  70 template<>                                              \
  71 struct ptr_helper<T&>                                   \
  72 {                                                       \
  73   typedef T value_type;                                 \
  74   typedef T& reference_type;                            \
  75   typedef T& rvalue_type;                               \
  76   static reference_type ref(T& r) { return r; }         \
  77   static const T& ref(const T& r) { return r; }         \
  78 };                                                      \
  79                                                         \
  80 template<>                                              \
  81 struct ptr_helper<T*>                                   \
  82 {                                                       \
  83   typedef T value_type;                                 \
  84   typedef T& reference_type;                            \
  85   typedef T* rvalue_type;                               \
  86   static reference_type ref(T * p) { return *p; }       \
  87   static const T& ref(const T * p) { return *p; }       \
  88 };                                                      \
  89 }}}
  90 #else
  91 # define BOOST_RANDOM_PTR_HELPER_SPEC(T)
  92 #endif
  93
  94 #endif // BOOST_RANDOM_DETAIL_PTR_HELPER_HPP