[3428] | 1 | #ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED |
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| 2 | #define BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED |
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| 3 | |
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| 4 | // |
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| 5 | // enable_shared_from_this2.hpp |
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| 6 | // |
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| 7 | // Copyright 2002, 2009 Peter Dimov |
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| 8 | // Copyright 2008 Frank Mori Hess |
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| 9 | // |
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| 10 | // Distributed under the Boost Software License, Version 1.0. |
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| 11 | // See accompanying file LICENSE_1_0.txt or copy at |
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| 12 | // http://www.boost.org/LICENSE_1_0.txt |
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| 13 | // |
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| 14 | |
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| 15 | #include <boost/config.hpp> |
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| 16 | #include <boost/shared_ptr.hpp> |
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| 17 | #include <boost/assert.hpp> |
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| 18 | #include <boost/detail/workaround.hpp> |
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| 19 | |
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| 20 | namespace boost |
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| 21 | { |
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| 22 | |
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| 23 | namespace detail |
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| 24 | { |
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| 25 | |
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| 26 | class esft2_deleter_wrapper |
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| 27 | { |
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| 28 | private: |
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| 29 | |
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| 30 | shared_ptr<void> deleter_; |
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| 31 | |
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| 32 | public: |
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| 33 | |
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| 34 | esft2_deleter_wrapper() |
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| 35 | { |
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| 36 | } |
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| 37 | |
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| 38 | template< class T > void set_deleter( shared_ptr<T> const & deleter ) |
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| 39 | { |
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| 40 | deleter_ = deleter; |
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| 41 | } |
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| 42 | |
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| 43 | template< class T> void operator()( T* ) |
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| 44 | { |
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| 45 | BOOST_ASSERT( deleter_.use_count() <= 1 ); |
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| 46 | deleter_.reset(); |
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| 47 | } |
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| 48 | }; |
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| 49 | |
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| 50 | } // namespace detail |
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| 51 | |
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| 52 | template< class T > class enable_shared_from_this2 |
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| 53 | { |
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| 54 | protected: |
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| 55 | |
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| 56 | enable_shared_from_this2() |
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| 57 | { |
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| 58 | } |
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| 59 | |
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| 60 | enable_shared_from_this2( enable_shared_from_this2 const & ) |
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| 61 | { |
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| 62 | } |
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| 63 | |
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| 64 | enable_shared_from_this2 & operator=( enable_shared_from_this2 const & ) |
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| 65 | { |
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| 66 | return *this; |
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| 67 | } |
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| 68 | |
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| 69 | ~enable_shared_from_this2() |
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| 70 | { |
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| 71 | BOOST_ASSERT( shared_this_.use_count() <= 1 ); // make sure no dangling shared_ptr objects exist |
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| 72 | } |
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| 73 | |
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| 74 | private: |
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| 75 | |
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| 76 | mutable weak_ptr<T> weak_this_; |
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| 77 | mutable shared_ptr<T> shared_this_; |
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| 78 | |
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| 79 | public: |
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| 80 | |
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| 81 | shared_ptr<T> shared_from_this() |
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| 82 | { |
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| 83 | init_weak_once(); |
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| 84 | return shared_ptr<T>( weak_this_ ); |
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| 85 | } |
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| 86 | |
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| 87 | shared_ptr<T const> shared_from_this() const |
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| 88 | { |
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| 89 | init_weak_once(); |
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| 90 | return shared_ptr<T>( weak_this_ ); |
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| 91 | } |
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| 92 | |
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| 93 | private: |
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| 94 | |
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| 95 | void init_weak_once() const |
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| 96 | { |
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| 97 | if( weak_this_._empty() ) |
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| 98 | { |
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| 99 | shared_this_.reset( static_cast< T* >( 0 ), detail::esft2_deleter_wrapper() ); |
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| 100 | weak_this_ = shared_this_; |
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| 101 | } |
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| 102 | } |
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| 103 | |
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| 104 | public: // actually private, but avoids compiler template friendship issues |
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| 105 | |
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| 106 | // Note: invoked automatically by shared_ptr; do not call |
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| 107 | template<class X, class Y> void _internal_accept_owner( shared_ptr<X> * ppx, Y * py ) const |
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| 108 | { |
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| 109 | BOOST_ASSERT( ppx != 0 ); |
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| 110 | |
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| 111 | if( weak_this_.use_count() == 0 ) |
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| 112 | { |
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| 113 | weak_this_ = shared_ptr<T>( *ppx, py ); |
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| 114 | } |
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| 115 | else if( shared_this_.use_count() != 0 ) |
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| 116 | { |
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| 117 | BOOST_ASSERT( ppx->unique() ); // no weak_ptrs should exist either, but there's no way to check that |
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| 118 | |
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| 119 | detail::esft2_deleter_wrapper * pd = boost::get_deleter<detail::esft2_deleter_wrapper>( shared_this_ ); |
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| 120 | BOOST_ASSERT( pd != 0 ); |
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| 121 | |
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| 122 | pd->set_deleter( *ppx ); |
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| 123 | |
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| 124 | ppx->reset( shared_this_, ppx->get() ); |
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| 125 | shared_this_.reset(); |
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| 126 | } |
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| 127 | } |
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| 128 | }; |
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| 129 | |
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| 130 | } // namespace boost |
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| 131 | |
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| 132 | #endif // #ifndef BOOST_ENABLE_SHARED_FROM_THIS2_HPP_INCLUDED |
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