sl@0: // Copyright David Abrahams 2002.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: #ifndef INSTANCE_HOLDER_DWA2002517_HPP
sl@0: # define INSTANCE_HOLDER_DWA2002517_HPP
sl@0: 
sl@0: # include <boost/python/detail/prefix.hpp>
sl@0: 
sl@0: # include <boost/utility.hpp>
sl@0: # include <boost/python/type_id.hpp>
sl@0: # include <cstddef>
sl@0: 
sl@0: namespace boost { namespace python { 
sl@0: 
sl@0: // Base class for all holders
sl@0: struct BOOST_PYTHON_DECL instance_holder : private noncopyable
sl@0: {
sl@0:  public:
sl@0:     instance_holder();
sl@0:     virtual ~instance_holder();
sl@0:     
sl@0:     // return the next holder in a chain
sl@0:     instance_holder* next() const;
sl@0: 
sl@0:     // When the derived holder actually holds by [smart] pointer and
sl@0:     // null_ptr_only is set, only report that the type is held when
sl@0:     // the pointer is null.  This is needed for proper shared_ptr
sl@0:     // support, to prevent holding shared_ptrs from being found when
sl@0:     // converting from python so that we can use the conversion method
sl@0:     // that always holds the Python object.
sl@0:     virtual void* holds(type_info, bool null_ptr_only) = 0;
sl@0: 
sl@0:     void install(PyObject* inst) throw();
sl@0: 
sl@0:     // These functions should probably be located elsewhere.
sl@0:     
sl@0:     // Allocate storage for an object of the given size at the given
sl@0:     // offset in the Python instance<> object if bytes are available
sl@0:     // there. Otherwise allocate size bytes of heap memory.
sl@0:     static void* allocate(PyObject*, std::size_t offset, std::size_t size);
sl@0: 
sl@0:     // Deallocate storage from the heap if it was not carved out of
sl@0:     // the given Python object by allocate(), above.
sl@0:     static void deallocate(PyObject*, void* storage) throw();
sl@0:  private:
sl@0:     instance_holder* m_next;
sl@0: };
sl@0: 
sl@0: // This macro is needed for implementation of derived holders
sl@0: # define BOOST_PYTHON_UNFORWARD(N,ignored) (typename unforward<A##N>::type)(a##N)
sl@0: 
sl@0: //
sl@0: // implementation
sl@0: //
sl@0: inline instance_holder* instance_holder::next() const
sl@0: {
sl@0:     return m_next;
sl@0: }
sl@0: 
sl@0: }} // namespace boost::python
sl@0: 
sl@0: #endif // INSTANCE_HOLDER_DWA2002517_HPP