Chris@16: // Copyright David Abrahams 2002.
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: #ifndef INSTANCE_HOLDER_DWA2002517_HPP
Chris@16: # define INSTANCE_HOLDER_DWA2002517_HPP
Chris@16: 
Chris@16: # include <boost/python/detail/prefix.hpp>
Chris@16: 
Chris@16: # include <boost/noncopyable.hpp>
Chris@16: # include <boost/python/type_id.hpp>
Chris@16: # include <cstddef>
Chris@16: 
Chris@16: namespace boost { namespace python { 
Chris@16: 
Chris@16: // Base class for all holders
Chris@16: struct BOOST_PYTHON_DECL instance_holder : private noncopyable
Chris@16: {
Chris@16:  public:
Chris@16:     instance_holder();
Chris@16:     virtual ~instance_holder();
Chris@16:     
Chris@16:     // return the next holder in a chain
Chris@16:     instance_holder* next() const;
Chris@16: 
Chris@16:     // When the derived holder actually holds by [smart] pointer and
Chris@16:     // null_ptr_only is set, only report that the type is held when
Chris@16:     // the pointer is null.  This is needed for proper shared_ptr
Chris@16:     // support, to prevent holding shared_ptrs from being found when
Chris@16:     // converting from python so that we can use the conversion method
Chris@16:     // that always holds the Python object.
Chris@16:     virtual void* holds(type_info, bool null_ptr_only) = 0;
Chris@16: 
Chris@16:     void install(PyObject* inst) throw();
Chris@16: 
Chris@16:     // These functions should probably be located elsewhere.
Chris@16:     
Chris@16:     // Allocate storage for an object of the given size at the given
Chris@16:     // offset in the Python instance<> object if bytes are available
Chris@16:     // there. Otherwise allocate size bytes of heap memory.
Chris@16:     static void* allocate(PyObject*, std::size_t offset, std::size_t size);
Chris@16: 
Chris@16:     // Deallocate storage from the heap if it was not carved out of
Chris@16:     // the given Python object by allocate(), above.
Chris@16:     static void deallocate(PyObject*, void* storage) throw();
Chris@16:  private:
Chris@16:     instance_holder* m_next;
Chris@16: };
Chris@16: 
Chris@16: // This macro is needed for implementation of derived holders
Chris@16: # define BOOST_PYTHON_UNFORWARD(N,ignored) (typename unforward<A##N>::type)(a##N)
Chris@16: 
Chris@16: //
Chris@16: // implementation
Chris@16: //
Chris@16: inline instance_holder* instance_holder::next() const
Chris@16: {
Chris@16:     return m_next;
Chris@16: }
Chris@16: 
Chris@16: }} // namespace boost::python
Chris@16: 
Chris@16: #endif // INSTANCE_HOLDER_DWA2002517_HPP