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 // Copyright David Abrahams 2002.
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 #ifndef DATA_MEMBERS_DWA2002328_HPP
 # define DATA_MEMBERS_DWA2002328_HPP
 
 # include <boost/python/detail/prefix.hpp>
 
 # include <boost/python/handle.hpp>
 
 # include <boost/python/return_value_policy.hpp>
 # include <boost/python/return_by_value.hpp>
 # include <boost/python/return_internal_reference.hpp>
 # include <boost/python/make_function.hpp>
 
 # include <boost/python/converter/builtin_converters.hpp>
 
 # include <boost/python/detail/indirect_traits.hpp>
 # include <boost/python/detail/not_specified.hpp>
 # include <boost/python/detail/value_arg.hpp>
 # include <boost/python/detail/type_traits.hpp>
 
 # include <boost/mpl/eval_if.hpp>
 # include <boost/mpl/if.hpp>
 # include <boost/mpl/vector/vector10.hpp>
 
 # include <boost/detail/workaround.hpp>
 
 namespace boost { namespace python { 
 
 //
 // This file defines the make_getter and make_setter function
 // families, which are responsible for turning pointers, references,
 // and pointers-to-data-members into callable Python objects which
 // can be used for attribute access on wrapped classes.
 //
 
 namespace detail
 {
 
   // A small function object which handles the getting and setting of
   // data members.
   template <class Data, class Class>
   struct member
   {
    public:      
       member(Data Class::*which) : m_which(which) {}
       
       Data& operator()(Class& c) const
       {
           return c.*m_which;
       }
 
       void operator()(Class& c, typename value_arg<Data>::type d) const
       {
           c.*m_which = d;
       }
    private:
       Data Class::*m_which;
   };
 
   // A small function object which handles the getting and setting of
   // non-member objects.
   template <class Data>
   struct datum
   {
    public:      
       datum(Data *which) : m_which(which) {}
       
       Data& operator()() const
       {
           return *m_which;
       }
 
       void operator()(typename value_arg<Data>::type d) const
       {
           *m_which = d;
       }
    private:
       Data *m_which;
   };
   
   //
   // Helper metafunction for determining the default CallPolicy to use
   // for attribute access.  If T is a [reference to a] class type X
   // whose conversion to python would normally produce a new copy of X
   // in a wrapped X class instance (as opposed to types such as
   // std::string, which are converted to native Python types, and
   // smart pointer types which produce a wrapped class instance of the
   // pointee type), to-python conversions will attempt to produce an
   // object which refers to the original C++ object, rather than a
   // copy.  See default_member_getter_policy for rationale.
   // 
   template <class T>
   struct default_getter_by_ref
       : mpl::and_<
           mpl::bool_<
               to_python_value<
                   typename value_arg<T>::type
               >::uses_registry
           >
         , indirect_traits::is_reference_to_class<
               typename value_arg<T>::type
           >
        >
   {
   };
 
   // Metafunction computing the default CallPolicy to use for reading
   // data members
   //
   // If it's a regular class type (not an object manager or other
   // type for which we have to_python specializations, use
   // return_internal_reference so that we can do things like
   //    x.y.z =  1
   // and get the right result.
   template <class T>
   struct default_member_getter_policy
     : mpl::if_<
           default_getter_by_ref<T>
         , return_internal_reference<>
         , return_value_policy<return_by_value>
       >
   {};
 
   // Metafunction computing the default CallPolicy to use for reading
   // non-member data.
   template <class T>
   struct default_datum_getter_policy
     : mpl::if_<
           default_getter_by_ref<T>
         , return_value_policy<reference_existing_object>
         , return_value_policy<return_by_value>
       >
   {};
 
   //
   // make_getter helper function family -- These helpers to
   // boost::python::make_getter are used to dispatch behavior.  The
   // third argument is a workaround for a CWPro8 partial ordering bug
   // with pointers to data members.  It should be convertible to
   // detail::true_ iff the first argument is a pointer-to-member, and
   // detail::false_ otherwise.  The fourth argument is for compilers
   // which don't support partial ordering at all and should always be
   // passed 0L.
 
 
 #if BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
   template <class D, class P>
   inline object make_getter(D& d, P& p, detail::false_, ...);
 #endif
 
   // Handle non-member pointers with policies
   template <class D, class Policies>
   inline object make_getter(D* d, Policies const& policies, detail::false_, int)
   {
       return python::make_function(
           detail::datum<D>(d), policies, mpl::vector1<D&>()
       );
   }
   
   // Handle non-member pointers without policies
   template <class D>
   inline object make_getter(D* d, not_specified, detail::false_, long)
   {
       typedef typename default_datum_getter_policy<D>::type policies;
       return detail::make_getter(d, policies(), detail::false_(), 0);
   }
 
   // Handle pointers-to-members with policies
   template <class C, class D, class Policies>
   inline object make_getter(D C::*pm, Policies const& policies, detail::true_, int)
   {
 #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
       typedef typename detail::remove_cv<C>::type Class;
 #else
       typedef C Class;
 #endif 
       return python::make_function(
           detail::member<D,Class>(pm)
         , policies
         , mpl::vector2<D&,Class&>()
       );
   }
       
   // Handle pointers-to-members without policies
   template <class C, class D>
   inline object make_getter(D C::*pm, not_specified, detail::true_, long)
   {
       typedef typename default_member_getter_policy<D>::type policies;
       return detail::make_getter(pm, policies(), detail::true_(), 0);
   }
 
   // Handle references
   template <class D, class P>
   inline object make_getter(D& d, P& p, detail::false_, ...)
   {
       // Just dispatch to the handler for pointer types.
       return detail::make_getter(&d, p, detail::false_(), 0L);
   }
 
   //
   // make_setter helper function family -- These helpers to
   // boost::python::make_setter are used to dispatch behavior.  The
   // third argument is for compilers which don't support partial
   // ordering at all and should always be passed 0.
   //
 
   
   // Handle non-member pointers
   template <class D, class Policies>
   inline object make_setter(D* p, Policies const& policies, detail::false_, int)
   {
       return python::make_function(
           detail::datum<D>(p), policies, mpl::vector2<void,D const&>()
       );
   }
 
   // Handle pointers-to-members
   template <class C, class D, class Policies>
   inline object make_setter(D C::*pm, Policies const& policies, detail::true_, int)
   {
       return python::make_function(
           detail::member<D,C>(pm)
         , policies
         , mpl::vector3<void, C&, D const&>()
       );
   }
 
   // Handle references
   template <class D, class Policies>
   inline object make_setter(D& x, Policies const& policies, detail::false_, ...)
   {
       return detail::make_setter(&x, policies, detail::false_(), 0L);
   }
 }
 
 //
 // make_getter function family -- build a callable object which
 // retrieves data through the first argument and is appropriate for
 // use as the `get' function in Python properties .  The second,
 // policies argument, is optional.  We need both D& and D const&
 // overloads in order be able to handle rvalues.
 //
 template <class D, class Policies>
 inline object make_getter(D& d, Policies const& policies)
 {
     return detail::make_getter(d, policies, detail::is_member_pointer<D>(), 0L);
 }
 
 template <class D, class Policies>
 inline object make_getter(D const& d, Policies const& policies)
 {
     return detail::make_getter(d, policies, detail::is_member_pointer<D>(), 0L);
 }
 
 template <class D>
 inline object make_getter(D& x)
 {
     detail::not_specified policy
         = detail::not_specified(); // suppress a SunPro warning
     return detail::make_getter(x, policy, detail::is_member_pointer<D>(), 0L);
 }
 
 #  if !BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
 template <class D>
 inline object make_getter(D const& d)
 {
     detail::not_specified policy
         = detail::not_specified(); // Suppress a SunPro warning
     return detail::make_getter(d, policy, detail::is_member_pointer<D>(), 0L);
 }
 #  endif
 
 //
 // make_setter function family -- build a callable object which
 // writes data through the first argument and is appropriate for
 // use as the `set' function in Python properties .  The second,
 // policies argument, is optional.  We need both D& and D const&
 // overloads in order be able to handle rvalues.
 //
 template <class D, class Policies>
 inline object make_setter(D& x, Policies const& policies)
 {
     return detail::make_setter(x, policies, detail::is_member_pointer<D>(), 0);
 }
 
 template <class D, class Policies>
 inline object make_setter(D const& x, Policies const& policies)
 {
     return detail::make_setter(x, policies, detail::is_member_pointer<D>(), 0);
 }
 
 template <class D>
 inline object make_setter(D& x)
 {
     return detail::make_setter(x, default_call_policies(), detail::is_member_pointer<D>(), 0);
 }
 
 # if !BOOST_WORKAROUND(__EDG_VERSION__, <= 238)
 template <class D>
 inline object make_setter(D const& x)
 {
     return detail::make_setter(x, default_call_policies(), detail::is_member_pointer<D>(), 0);
 }
 # endif
 
 }} // namespace boost::python
 
 #endif // DATA_MEMBERS_DWA2002328_HPP

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