ceph/src/boost/boost/smart_ptr/weak_ptr.hpp

   1 #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
   3
   4 //
   5 //  weak_ptr.hpp
   6 //
   7 //  Copyright (c) 2001, 2002, 2003 Peter Dimov
   8 //
   9 //  Distributed under the Boost Software License, Version 1.0. (See
  10 //  accompanying file LICENSE_1_0.txt or copy at
  11 //  http://www.boost.org/LICENSE_1_0.txt)
  12 //
  13 //  See http://www.boost.org/libs/smart_ptr/ for documentation.
  14 //
  15
  16 #include <memory> // boost.TR1 include order fix
  17 #include <boost/smart_ptr/detail/shared_count.hpp>
  18 #include <boost/smart_ptr/shared_ptr.hpp>
  19 #include <boost/smart_ptr/detail/sp_noexcept.hpp>
  20
  21 namespace boost
  22 {
  23
  24 template<class T> class weak_ptr
  25 {
  26 private:
  27
  28     // Borland 5.5.1 specific workarounds
  29     typedef weak_ptr<T> this_type;
  30
  31 public:
  32
  33     typedef typename boost::detail::sp_element< T >::type element_type;
  34
  35     BOOST_CONSTEXPR weak_ptr() BOOST_SP_NOEXCEPT : px(0), pn()
  36     {
  37     }
  38
  39 //  generated copy constructor, assignment, destructor are fine...
  40
  41 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  42
  43 // ... except in C++0x, move disables the implicit copy
  44
  45     weak_ptr( weak_ptr const & r ) BOOST_SP_NOEXCEPT : px( r.px ), pn( r.pn )
  46     {
  47     }
  48
  49     weak_ptr & operator=( weak_ptr const & r ) BOOST_SP_NOEXCEPT
  50     {
  51         px = r.px;
  52         pn = r.pn;
  53         return *this;
  54     }
  55
  56 #endif
  57
  58 //
  59 //  The "obvious" converting constructor implementation:
  60 //
  61 //  template<class Y>
  62 //  weak_ptr(weak_ptr<Y> const & r): px(r.px), pn(r.pn)
  63 //  {
  64 //  }
  65 //
  66 //  has a serious problem.
  67 //
  68 //  r.px may already have been invalidated. The px(r.px)
  69 //  conversion may require access to *r.px (virtual inheritance).
  70 //
  71 //  It is not possible to avoid spurious access violations since
  72 //  in multithreaded programs r.px may be invalidated at any point.
  73 //
  74
  75     template<class Y>
  76 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
  77
  78     weak_ptr( weak_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
  79
  80 #else
  81
  82     weak_ptr( weak_ptr<Y> const & r )
  83
  84 #endif
  85     BOOST_SP_NOEXCEPT : px(r.lock().get()), pn(r.pn)
  86     {
  87         boost::detail::sp_assert_convertible< Y, T >();
  88     }
  89
  90 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  91
  92     template<class Y>
  93 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
  94
  95     weak_ptr( weak_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
  96
  97 #else
  98
  99     weak_ptr( weak_ptr<Y> && r )
 100
 101 #endif
 102     BOOST_SP_NOEXCEPT : px( r.lock().get() ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
 103     {
 104         boost::detail::sp_assert_convertible< Y, T >();
 105         r.px = 0;
 106     }
 107
 108     // for better efficiency in the T == Y case
 109     weak_ptr( weak_ptr && r )
 110     BOOST_SP_NOEXCEPT : px( r.px ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
 111     {
 112         r.px = 0;
 113     }
 114
 115     // for better efficiency in the T == Y case
 116     weak_ptr & operator=( weak_ptr && r ) BOOST_SP_NOEXCEPT
 117     {
 118         this_type( static_cast< weak_ptr && >( r ) ).swap( *this );
 119         return *this;
 120     }
 121
 122
 123 #endif
 124
 125     template<class Y>
 126 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
 127
 128     weak_ptr( shared_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
 129
 130 #else
 131
 132     weak_ptr( shared_ptr<Y> const & r )
 133
 134 #endif
 135     BOOST_SP_NOEXCEPT : px( r.px ), pn( r.pn )
 136     {
 137         boost::detail::sp_assert_convertible< Y, T >();
 138     }
 139
 140 #if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1300)
 141
 142     template<class Y>
 143     weak_ptr & operator=( weak_ptr<Y> const & r ) BOOST_SP_NOEXCEPT
 144     {
 145         boost::detail::sp_assert_convertible< Y, T >();
 146
 147         px = r.lock().get();
 148         pn = r.pn;
 149
 150         return *this;
 151     }
 152
 153 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
 154
 155     template<class Y>
 156     weak_ptr & operator=( weak_ptr<Y> && r ) BOOST_SP_NOEXCEPT
 157     {
 158         this_type( static_cast< weak_ptr<Y> && >( r ) ).swap( *this );
 159         return *this;
 160     }
 161
 162 #endif
 163
 164     template<class Y>
 165     weak_ptr & operator=( shared_ptr<Y> const & r ) BOOST_SP_NOEXCEPT
 166     {
 167         boost::detail::sp_assert_convertible< Y, T >();
 168
 169         px = r.px;
 170         pn = r.pn;
 171
 172         return *this;
 173     }
 174
 175 #endif
 176
 177     shared_ptr<T> lock() const BOOST_SP_NOEXCEPT
 178     {
 179         return shared_ptr<T>( *this, boost::detail::sp_nothrow_tag() );
 180     }
 181
 182     long use_count() const BOOST_SP_NOEXCEPT
 183     {
 184         return pn.use_count();
 185     }
 186
 187     bool expired() const BOOST_SP_NOEXCEPT
 188     {
 189         return pn.use_count() == 0;
 190     }
 191
 192     bool _empty() const BOOST_SP_NOEXCEPT // extension, not in std::weak_ptr
 193     {
 194         return pn.empty();
 195     }
 196
 197     void reset() BOOST_SP_NOEXCEPT
 198     {
 199         this_type().swap(*this);
 200     }
 201
 202     void swap(this_type & other) BOOST_SP_NOEXCEPT
 203     {
 204         std::swap(px, other.px);
 205         pn.swap(other.pn);
 206     }
 207
 208     template<typename Y>
 209     void _internal_aliasing_assign(weak_ptr<Y> const & r, element_type * px2) BOOST_SP_NOEXCEPT
 210     {
 211         px = px2;
 212         pn = r.pn;
 213     }
 214
 215     template<class Y> bool owner_before( weak_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
 216     {
 217         return pn < rhs.pn;
 218     }
 219
 220     template<class Y> bool owner_before( shared_ptr<Y> const & rhs ) const BOOST_SP_NOEXCEPT
 221     {
 222         return pn < rhs.pn;
 223     }
 224
 225 // Tasteless as this may seem, making all members public allows member templates
 226 // to work in the absence of member template friends. (Matthew Langston)
 227
 228 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
 229
 230 private:
 231
 232     template<class Y> friend class weak_ptr;
 233     template<class Y> friend class shared_ptr;
 234
 235 #endif
 236
 237     element_type * px;            // contained pointer
 238     boost::detail::weak_count pn; // reference counter
 239
 240 };  // weak_ptr
 241
 242 template<class T, class U> inline bool operator<(weak_ptr<T> const & a, weak_ptr<U> const & b) BOOST_SP_NOEXCEPT
 243 {
 244     return a.owner_before( b );
 245 }
 246
 247 template<class T> void swap(weak_ptr<T> & a, weak_ptr<T> & b) BOOST_SP_NOEXCEPT
 248 {
 249     a.swap(b);
 250 }
 251
 252 } // namespace boost
 253
 254 #endif  // #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED