source: NonGTP/Boost/boost/python/instance_holder.hpp @ 857

Revision 857, 2.1 KB checked in by igarcia, 19 years ago (diff)
Line 
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/utility.hpp>
11# include <boost/python/type_id.hpp>
12# include <cstddef>
13
14namespace boost { namespace python {
15
16// Base class for all holders
17struct 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//
56inline instance_holder* instance_holder::next() const
57{
58    return m_next;
59}
60
61}} // namespace boost::python
62
63#endif // INSTANCE_HOLDER_DWA2002517_HPP
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