| 1 | // Copyright David Abrahams 2002. |
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| 2 | // Distributed under the Boost Software License, Version 1.0. (See |
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| 3 | // accompanying file LICENSE_1_0.txt or copy at |
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| 4 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 5 | #ifndef INSTANCE_HOLDER_DWA2002517_HPP |
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| 6 | # define INSTANCE_HOLDER_DWA2002517_HPP |
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| 7 | |
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| 8 | # include <boost/python/detail/prefix.hpp> |
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| 9 | |
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| 10 | # include <boost/noncopyable.hpp> |
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| 11 | # include <boost/python/type_id.hpp> |
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| 12 | # include <cstddef> |
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| 13 | |
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| 14 | namespace boost { namespace python { |
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| 15 | |
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| 16 | // Base class for all holders |
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| 17 | struct BOOST_PYTHON_DECL instance_holder : private noncopyable |
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| 18 | { |
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| 19 | public: |
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| 20 | instance_holder(); |
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| 21 | virtual ~instance_holder(); |
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| 22 | |
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| 23 | // return the next holder in a chain |
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| 24 | instance_holder* next() const; |
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| 25 | |
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| 26 | // When the derived holder actually holds by [smart] pointer and |
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| 27 | // null_ptr_only is set, only report that the type is held when |
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| 28 | // the pointer is null. This is needed for proper shared_ptr |
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| 29 | // support, to prevent holding shared_ptrs from being found when |
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| 30 | // converting from python so that we can use the conversion method |
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| 31 | // that always holds the Python object. |
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| 32 | virtual void* holds(type_info, bool null_ptr_only) = 0; |
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| 33 | |
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| 34 | void install(PyObject* inst) throw(); |
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| 35 | |
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| 36 | // These functions should probably be located elsewhere. |
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| 37 | |
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| 38 | // Allocate storage for an object of the given size at the given |
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| 39 | // offset in the Python instance<> object if bytes are available |
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| 40 | // there. Otherwise allocate size bytes of heap memory. |
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| 41 | static void* allocate(PyObject*, std::size_t offset, std::size_t size); |
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| 42 | |
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| 43 | // Deallocate storage from the heap if it was not carved out of |
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| 44 | // the given Python object by allocate(), above. |
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| 45 | static void deallocate(PyObject*, void* storage) throw(); |
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| 46 | private: |
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| 47 | instance_holder* m_next; |
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| 48 | }; |
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| 49 | |
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| 50 | // This macro is needed for implementation of derived holders |
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| 51 | # define BOOST_PYTHON_UNFORWARD(N,ignored) (typename unforward<A##N>::type)(a##N) |
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| 52 | |
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| 53 | // |
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| 54 | // implementation |
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| 55 | // |
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| 56 | inline instance_holder* instance_holder::next() const |
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| 57 | { |
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| 58 | return m_next; |
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| 59 | } |
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| 60 | |
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| 61 | }} // namespace boost::python |
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| 62 | |
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| 63 | #endif // INSTANCE_HOLDER_DWA2002517_HPP |
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| 64 | |
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