ceph/src/boost/boost/python/data_members.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 DATA_MEMBERS_DWA2002328_HPP
   6 # define DATA_MEMBERS_DWA2002328_HPP
   7
   8 # include <boost/python/detail/prefix.hpp>
   9
  10 # include <boost/python/handle.hpp>
  11
  12 # include <boost/python/return_value_policy.hpp>
  13 # include <boost/python/return_by_value.hpp>
  14 # include <boost/python/return_internal_reference.hpp>
  15 # include <boost/python/make_function.hpp>
  16
  17 # include <boost/python/converter/builtin_converters.hpp>
  18
  19 # include <boost/python/detail/indirect_traits.hpp>
  20 # include <boost/python/detail/not_specified.hpp>
  21 # include <boost/python/detail/value_arg.hpp>
  22 # include <boost/python/detail/type_traits.hpp>
  23
  24 # include <boost/mpl/eval_if.hpp>
  25 # include <boost/mpl/if.hpp>
  26 # include <boost/mpl/vector/vector10.hpp>
  27
  28 # include <boost/detail/workaround.hpp>
  29
  30 namespace boost { namespace python {
  31
  32 //
  33 // This file defines the make_getter and make_setter function
  34 // families, which are responsible for turning pointers, references,
  35 // and pointers-to-data-members into callable Python objects which
  36 // can be used for attribute access on wrapped classes.
  37 //
  38
  39 namespace detail
  40 {
  41
  42   // A small function object which handles the getting and setting of
  43   // data members.
  44   template <class Data, class Class>
  45   struct member
  46   {
  47    public:
  48       member(Data Class::*which) : m_which(which) {}
  49
  50       Data& operator()(Class& c) const
  51       {
  52           return c.*m_which;
  53       }
  54
  55       void operator()(Class& c, typename value_arg<Data>::type d) const
  56       {
  57           c.*m_which = d;
  58       }
  59    private:
  60       Data Class::*m_which;
  61   };
  62
  63   // A small function object which handles the getting and setting of
  64   // non-member objects.
  65   template <class Data>
  66   struct datum
  67   {
  68    public:
  69       datum(Data *which) : m_which(which) {}
  70
  71       Data& operator()() const
  72       {
  73           return *m_which;
  74       }
  75
  76       void operator()(typename value_arg<Data>::type d) const
  77       {
  78           *m_which = d;
  79       }
  80    private:
  81       Data *m_which;
  82   };
  83
  84   //
  85   // Helper metafunction for determining the default CallPolicy to use
  86   // for attribute access.  If T is a [reference to a] class type X
  87   // whose conversion to python would normally produce a new copy of X
  88   // in a wrapped X class instance (as opposed to types such as
  89   // std::string, which are converted to native Python types, and
  90   // smart pointer types which produce a wrapped class instance of the
  91   // pointee type), to-python conversions will attempt to produce an
  92   // object which refers to the original C++ object, rather than a
  93   // copy.  See default_member_getter_policy for rationale.
  94   //
  95   template <class T>
  96   struct default_getter_by_ref
  97       : mpl::and_<
  98           mpl::bool_<
  99               to_python_value<
 100                   typename value_arg<T>::type
 101               >::uses_registry
 102           >
 103         , indirect_traits::is_reference_to_class<
 104               typename value_arg<T>::type
 105           >
 106        >
 107   {
 108   };
 109
 110   // Metafunction computing the default CallPolicy to use for reading
 111   // data members
 112   //
 113   // If it's a regular class type (not an object manager or other
 114   // type for which we have to_python specializations, use
 115   // return_internal_reference so that we can do things like
 116   //    x.y.z =  1
 117   // and get the right result.
 118   template <class T>
 119   struct default_member_getter_policy
 120     : mpl::if_<
 121           default_getter_by_ref<T>
 122         , return_internal_reference<>
 123         , return_value_policy<return_by_value>
 124       >
 125   {};
 126
 127   // Metafunction computing the default CallPolicy to use for reading
 128   // non-member data.
 129   template <class T>
 130   struct default_datum_getter_policy
 131     : mpl::if_<
 132           default_getter_by_ref<T>
 133         , return_value_policy<reference_existing_object>
 134         , return_value_policy<return_by_value>
 135       >
 136   {};
 137
 138   //
 139   // make_getter helper function family -- These helpers to
 140   // boost::python::make_getter are used to dispatch behavior.  The
 141   // third argument is a workaround for a CWPro8 partial ordering bug
 142   // with pointers to data members.  It should be convertible to
 143   // detail::true_ iff the first argument is a pointer-to-member, and
 144   // detail::false_ otherwise.  The fourth argument is for compilers
 145   // which don't support partial ordering at all and should always be
 146   // passed 0L.
 147
 148
 149 #if BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
 150   template <class D, class P>
 151   inline object make_getter(D& d, P& p, detail::false_, ...);
 152 #endif
 153
 154   // Handle non-member pointers with policies
 155   template <class D, class Policies>
 156   inline object make_getter(D* d, Policies const& policies, detail::false_, int)
 157   {
 158       return python::make_function(
 159           detail::datum<D>(d), policies, mpl::vector1<D&>()
 160       );
 161   }
 162
 163   // Handle non-member pointers without policies
 164   template <class D>
 165   inline object make_getter(D* d, not_specified, detail::false_, long)
 166   {
 167       typedef typename default_datum_getter_policy<D>::type policies;
 168       return detail::make_getter(d, policies(), detail::false_(), 0);
 169   }
 170
 171   // Handle pointers-to-members with policies
 172   template <class C, class D, class Policies>
 173   inline object make_getter(D C::*pm, Policies const& policies, detail::true_, int)
 174   {
 175 #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
 176       typedef typename detail::remove_cv<C>::type Class;
 177 #else
 178       typedef C Class;
 179 #endif
 180       return python::make_function(
 181           detail::member<D,Class>(pm)
 182         , policies
 183         , mpl::vector2<D&,Class&>()
 184       );
 185   }
 186
 187   // Handle pointers-to-members without policies
 188   template <class C, class D>
 189   inline object make_getter(D C::*pm, not_specified, detail::true_, long)
 190   {
 191       typedef typename default_member_getter_policy<D>::type policies;
 192       return detail::make_getter(pm, policies(), detail::true_(), 0);
 193   }
 194
 195   // Handle references
 196   template <class D, class P>
 197   inline object make_getter(D& d, P& p, detail::false_, ...)
 198   {
 199       // Just dispatch to the handler for pointer types.
 200       return detail::make_getter(&d, p, detail::false_(), 0L);
 201   }
 202
 203   //
 204   // make_setter helper function family -- These helpers to
 205   // boost::python::make_setter are used to dispatch behavior.  The
 206   // third argument is for compilers which don't support partial
 207   // ordering at all and should always be passed 0.
 208   //
 209
 210
 211   // Handle non-member pointers
 212   template <class D, class Policies>
 213   inline object make_setter(D* p, Policies const& policies, detail::false_, int)
 214   {
 215       return python::make_function(
 216           detail::datum<D>(p), policies, mpl::vector2<void,D const&>()
 217       );
 218   }
 219
 220   // Handle pointers-to-members
 221   template <class C, class D, class Policies>
 222   inline object make_setter(D C::*pm, Policies const& policies, detail::true_, int)
 223   {
 224       return python::make_function(
 225           detail::member<D,C>(pm)
 226         , policies
 227         , mpl::vector3<void, C&, D const&>()
 228       );
 229   }
 230
 231   // Handle references
 232   template <class D, class Policies>
 233   inline object make_setter(D& x, Policies const& policies, detail::false_, ...)
 234   {
 235       return detail::make_setter(&x, policies, detail::false_(), 0L);
 236   }
 237 }
 238
 239 //
 240 // make_getter function family -- build a callable object which
 241 // retrieves data through the first argument and is appropriate for
 242 // use as the `get' function in Python properties .  The second,
 243 // policies argument, is optional.  We need both D& and D const&
 244 // overloads in order be able to handle rvalues.
 245 //
 246 template <class D, class Policies>
 247 inline object make_getter(D& d, Policies const& policies)
 248 {
 249     return detail::make_getter(d, policies, detail::is_member_pointer<D>(), 0L);
 250 }
 251
 252 template <class D, class Policies>
 253 inline object make_getter(D const& d, Policies const& policies)
 254 {
 255     return detail::make_getter(d, policies, detail::is_member_pointer<D>(), 0L);
 256 }
 257
 258 template <class D>
 259 inline object make_getter(D& x)
 260 {
 261     detail::not_specified policy
 262         = detail::not_specified(); // suppress a SunPro warning
 263     return detail::make_getter(x, policy, detail::is_member_pointer<D>(), 0L);
 264 }
 265
 266 #  if !BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
 267 template <class D>
 268 inline object make_getter(D const& d)
 269 {
 270     detail::not_specified policy
 271         = detail::not_specified(); // Suppress a SunPro warning
 272     return detail::make_getter(d, policy, detail::is_member_pointer<D>(), 0L);
 273 }
 274 #  endif
 275
 276 //
 277 // make_setter function family -- build a callable object which
 278 // writes data through the first argument and is appropriate for
 279 // use as the `set' function in Python properties .  The second,
 280 // policies argument, is optional.  We need both D& and D const&
 281 // overloads in order be able to handle rvalues.
 282 //
 283 template <class D, class Policies>
 284 inline object make_setter(D& x, Policies const& policies)
 285 {
 286     return detail::make_setter(x, policies, detail::is_member_pointer<D>(), 0);
 287 }
 288
 289 template <class D, class Policies>
 290 inline object make_setter(D const& x, Policies const& policies)
 291 {
 292     return detail::make_setter(x, policies, detail::is_member_pointer<D>(), 0);
 293 }
 294
 295 template <class D>
 296 inline object make_setter(D& x)
 297 {
 298     return detail::make_setter(x, default_call_policies(), detail::is_member_pointer<D>(), 0);
 299 }
 300
 301 # if !BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
 302 template <class D>
 303 inline object make_setter(D const& x)
 304 {
 305     return detail::make_setter(x, default_call_policies(), detail::is_member_pointer<D>(), 0);
 306 }
 307 # endif
 308
 309 }} // namespace boost::python
 310
 311 #endif // DATA_MEMBERS_DWA2002328_HPP