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 INSTANCE_HOLDER_DWA2002517_HPP 6 # define INSTANCE_HOLDER_DWA2002517_HPP 7 8 # include <boost/python/detail/prefix.hpp> 9 10 # include <boost/noncopyable.hpp> 11 # include <boost/python/type_id.hpp> 12 # include <cstddef> 13 14 namespace boost { namespace python { 15 16 // Base class for all holders 17 struct BOOST_PYTHON_DECL instance_holder : private noncopyable 18 { 19 public: 20 instance_holder(); 21 virtual ~instance_holder(); 22 23 // return the next holder in a chain 24 instance_holder* next() const; 25 26 // When the derived holder actually holds by [smart] pointer and 27 // null_ptr_only is set, only report that the type is held when 28 // the pointer is null. This is needed for proper shared_ptr 29 // support, to prevent holding shared_ptrs from being found when 30 // converting from python so that we can use the conversion method 31 // that always holds the Python object. 32 virtual void* holds(type_info, bool null_ptr_only) = 0; 33 34 void install(PyObject* inst) throw(); 35 36 // These functions should probably be located elsewhere. 37 38 // Allocate storage for an object of the given size at the given 39 // offset in the Python instance<> object if bytes are available 40 // there. Otherwise allocate size bytes of heap memory. 41 static void* allocate(PyObject*, std::size_t offset, std::size_t size); 42 43 // Deallocate storage from the heap if it was not carved out of 44 // the given Python object by allocate(), above. 45 static void deallocate(PyObject*, void* storage) throw(); 46 private: 47 instance_holder* m_next; 48 }; 49 50 // This macro is needed for implementation of derived holders 51 # define BOOST_PYTHON_UNFORWARD(N,ignored) (typename unforward<A##N>::type)(a##N) 52 53 // 54 // implementation 55 // next() const56inline instance_holder* instance_holder::next() const 57 { 58 return m_next; 59 } 60 61 }} // namespace boost::python 62 63 #endif // INSTANCE_HOLDER_DWA2002517_HPP 64