libstdc++-v3/include/bits/shared_ptr.h

   1 // shared_ptr and weak_ptr implementation -*- C++ -*-
   2
   3 // Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 // GCC Note: Based on files from version 1.32.0 of the Boost library.
  26
  27 //  shared_count.hpp
  28 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
  29
  30 //  shared_ptr.hpp
  31 //  Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
  32 //  Copyright (C) 2001, 2002, 2003 Peter Dimov
  33
  34 //  weak_ptr.hpp
  35 //  Copyright (C) 2001, 2002, 2003 Peter Dimov
  36
  37 //  enable_shared_from_this.hpp
  38 //  Copyright (C) 2002 Peter Dimov
  39
  40 // Distributed under the Boost Software License, Version 1.0. (See
  41 // accompanying file LICENSE_1_0.txt or copy at
  42 // http://www.boost.org/LICENSE_1_0.txt)
  43
  44 /** @file bits/shared_ptr.h
  45  *  This is an internal header file, included by other library headers.
  46  *  You should not attempt to use it directly.
  47  */
  48
  49 #ifndef _SHARED_PTR_H
  50 #define _SHARED_PTR_H 1
  51
  52 #include <bits/shared_ptr_base.h>
  53
  54 _GLIBCXX_BEGIN_NAMESPACE(std)
  55
  56   /**
  57    * @addtogroup pointer_abstractions
  58    * @{
  59    */
  60
  61   /// 2.2.3.7 shared_ptr I/O
  62   template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
  63     std::basic_ostream<_Ch, _Tr>&
  64     operator<<(std::basic_ostream<_Ch, _Tr>& __os,
  65                const __shared_ptr<_Tp, _Lp>& __p)
  66     {
  67       __os << __p.get();
  68       return __os;
  69     }
  70
  71   /// 2.2.3.10 shared_ptr get_deleter (experimental)
  72   template<typename _Del, typename _Tp, _Lock_policy _Lp>
  73     inline _Del*
  74     get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
  75     {
  76 #ifdef __GXX_RTTI
  77       return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
  78 #else
  79       return 0;
  80 #endif
  81     }
  82
  83
  84   /**
  85    *  @brief  A smart pointer with reference-counted copy semantics.
  86    *
  87    *  The object pointed to is deleted when the last shared_ptr pointing to
  88    *  it is destroyed or reset.
  89   */
  90   template<typename _Tp>
  91     class shared_ptr : public __shared_ptr<_Tp>
  92     {
  93     public:
  94       /**
  95        *  @brief  Construct an empty %shared_ptr.
  96        *  @post   use_count()==0 && get()==0
  97        */
  98       shared_ptr() : __shared_ptr<_Tp>() { }
  99
 100       /**
 101        *  @brief  Construct a %shared_ptr that owns the pointer @a __p.
 102        *  @param  __p  A pointer that is convertible to element_type*.
 103        *  @post   use_count() == 1 && get() == __p
 104        *  @throw  std::bad_alloc, in which case @c delete @a __p is called.
 105        */
 106       template<typename _Tp1>
 107         explicit shared_ptr(_Tp1* __p) : __shared_ptr<_Tp>(__p) { }
 108
 109       /**
 110        *  @brief  Construct a %shared_ptr that owns the pointer @a __p
 111        *          and the deleter @a __d.
 112        *  @param  __p  A pointer.
 113        *  @param  __d  A deleter.
 114        *  @post   use_count() == 1 && get() == __p
 115        *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
 116        *
 117        *  Requirements: _Deleter's copy constructor and destructor must
 118        *  not throw
 119        *
 120        *  __shared_ptr will release __p by calling __d(__p)
 121        */
 122         template<typename _Tp1, typename _Deleter>
 123         shared_ptr(_Tp1* __p, _Deleter __d) : __shared_ptr<_Tp>(__p, __d) { }
 124
 125       /**
 126        *  @brief  Construct a %shared_ptr that owns the pointer @a __p
 127        *          and the deleter @a __d.
 128        *  @param  __p  A pointer.
 129        *  @param  __d  A deleter.
 130        *  @param  __a  An allocator.
 131        *  @post   use_count() == 1 && get() == __p
 132        *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
 133        *
 134        *  Requirements: _Deleter's copy constructor and destructor must
 135        *  not throw _Alloc's copy constructor and destructor must not
 136        *  throw.
 137        *
 138        *  __shared_ptr will release __p by calling __d(__p)
 139        */
 140       template<typename _Tp1, typename _Deleter, typename _Alloc>
 141         shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
 142         : __shared_ptr<_Tp>(__p, __d, __a) { }
 143
 144       // Aliasing constructor
 145
 146       /**
 147        *  @brief  Constructs a %shared_ptr instance that stores @a __p
 148        *          and shares ownership with @a __r.
 149        *  @param  __r  A %shared_ptr.
 150        *  @param  __p  A pointer that will remain valid while @a *__r is valid.
 151        *  @post   get() == __p && use_count() == __r.use_count()
 152        *
 153        *  This can be used to construct a @c shared_ptr to a sub-object
 154        *  of an object managed by an existing @c shared_ptr.
 155        *
 156        * @code
 157        * shared_ptr< pair<int,int> > pii(new pair<int,int>());
 158        * shared_ptr<int> pi(pii, &pii->first);
 159        * assert(pii.use_count() == 2);
 160        * @endcode
 161        */
 162       template<typename _Tp1>
 163         shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
 164         : __shared_ptr<_Tp>(__r, __p) { }
 165
 166       /**
 167        *  @brief  If @a __r is empty, constructs an empty %shared_ptr;
 168        *          otherwise construct a %shared_ptr that shares ownership
 169        *          with @a __r.
 170        *  @param  __r  A %shared_ptr.
 171        *  @post   get() == __r.get() && use_count() == __r.use_count()
 172        */
 173       template<typename _Tp1>
 174         shared_ptr(const shared_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { }
 175
 176       /**
 177        *  @brief  Move-constructs a %shared_ptr instance from @a __r.
 178        *  @param  __r  A %shared_ptr rvalue.
 179        *  @post   *this contains the old value of @a __r, @a __r is empty.
 180        */
 181       shared_ptr(shared_ptr&& __r)
 182       : __shared_ptr<_Tp>(std::move(__r)) { }
 183
 184       /**
 185        *  @brief  Move-constructs a %shared_ptr instance from @a __r.
 186        *  @param  __r  A %shared_ptr rvalue.
 187        *  @post   *this contains the old value of @a __r, @a __r is empty.
 188        */
 189       template<typename _Tp1>
 190         shared_ptr(shared_ptr<_Tp1>&& __r)
 191         : __shared_ptr<_Tp>(std::move(__r)) { }
 192
 193       /**
 194        *  @brief  Constructs a %shared_ptr that shares ownership with @a __r
 195        *          and stores a copy of the pointer stored in @a __r.
 196        *  @param  __r  A weak_ptr.
 197        *  @post   use_count() == __r.use_count()
 198        *  @throw  bad_weak_ptr when __r.expired(),
 199        *          in which case the constructor has no effect.
 200        */
 201       template<typename _Tp1>
 202         explicit shared_ptr(const weak_ptr<_Tp1>& __r)
 203         : __shared_ptr<_Tp>(__r) { }
 204
 205 #if _GLIBCXX_DEPRECATED
 206       template<typename _Tp1>
 207         explicit
 208         shared_ptr(std::auto_ptr<_Tp1>&& __r)
 209         : __shared_ptr<_Tp>(std::move(__r)) { }
 210 #endif
 211
 212       template<typename _Tp1, typename _Del>
 213         explicit shared_ptr(const std::unique_ptr<_Tp1, _Del>&) = delete;
 214
 215       template<typename _Tp1, typename _Del>
 216         explicit shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
 217         : __shared_ptr<_Tp>(std::move(__r)) { }
 218
 219       template<typename _Tp1>
 220         shared_ptr&
 221         operator=(const shared_ptr<_Tp1>& __r) // never throws
 222         {
 223           this->__shared_ptr<_Tp>::operator=(__r);
 224           return *this;
 225         }
 226
 227 #if _GLIBCXX_DEPRECATED
 228       template<typename _Tp1>
 229         shared_ptr&
 230         operator=(std::auto_ptr<_Tp1>&& __r)
 231         {
 232           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 233           return *this;
 234         }
 235 #endif
 236
 237       shared_ptr&
 238       operator=(shared_ptr&& __r)
 239       {
 240         this->__shared_ptr<_Tp>::operator=(std::move(__r));
 241         return *this;
 242       }
 243
 244       template<class _Tp1>
 245         shared_ptr&
 246         operator=(shared_ptr<_Tp1>&& __r)
 247         {
 248           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 249           return *this;
 250         }
 251
 252       template<typename _Tp1, typename _Del>
 253         shared_ptr&
 254         operator=(const std::unique_ptr<_Tp1, _Del>& __r) = delete;
 255
 256       template<typename _Tp1, typename _Del>
 257         shared_ptr&
 258         operator=(std::unique_ptr<_Tp1, _Del>&& __r)
 259         {
 260           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 261           return *this;
 262         }
 263
 264     private:
 265       // This constructor is non-standard, it is used by allocate_shared.
 266       template<typename _Alloc, typename... _Args>
 267         shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
 268         : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
 269         { }
 270
 271       template<typename _Tp1, typename _Alloc, typename... _Args>
 272         friend shared_ptr<_Tp1>
 273         allocate_shared(_Alloc __a, _Args&&... __args);
 274     };
 275
 276   // 20.8.13.2.7 shared_ptr comparisons
 277   template<typename _Tp1, typename _Tp2>
 278     inline bool
 279     operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 280     { return __a.get() == __b.get(); }
 281
 282   template<typename _Tp1, typename _Tp2>
 283     inline bool
 284     operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 285     { return __a.get() != __b.get(); }
 286
 287   template<typename _Tp1, typename _Tp2>
 288     inline bool
 289     operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 290     { return __a.get() < __b.get(); }
 291
 292   template<typename _Tp>
 293     struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
 294     { };
 295
 296   // 20.8.13.2.9 shared_ptr specialized algorithms.
 297   template<typename _Tp>
 298     inline void
 299     swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
 300     { __a.swap(__b); }
 301
 302   // 20.8.13.2.10 shared_ptr casts.
 303   template<typename _Tp, typename _Tp1>
 304     inline shared_ptr<_Tp>
 305     static_pointer_cast(const shared_ptr<_Tp1>& __r)
 306     { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
 307
 308   template<typename _Tp, typename _Tp1>
 309     inline shared_ptr<_Tp>
 310     const_pointer_cast(const shared_ptr<_Tp1>& __r)
 311     { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
 312
 313   template<typename _Tp, typename _Tp1>
 314     inline shared_ptr<_Tp>
 315     dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
 316     {
 317       if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
 318         return shared_ptr<_Tp>(__r, __p);
 319       return shared_ptr<_Tp>();
 320     }
 321
 322
 323   /**
 324    *  @brief  A smart pointer with weak semantics.
 325    *
 326    *  With forwarding constructors and assignment operators.
 327    */
 328   template<typename _Tp>
 329     class weak_ptr : public __weak_ptr<_Tp>
 330     {
 331     public:
 332       weak_ptr() : __weak_ptr<_Tp>() { }
 333
 334       template<typename _Tp1>
 335         weak_ptr(const weak_ptr<_Tp1>& __r)
 336         : __weak_ptr<_Tp>(__r) { }
 337
 338       template<typename _Tp1>
 339         weak_ptr(const shared_ptr<_Tp1>& __r)
 340         : __weak_ptr<_Tp>(__r) { }
 341
 342       template<typename _Tp1>
 343         weak_ptr&
 344         operator=(const weak_ptr<_Tp1>& __r) // never throws
 345         {
 346           this->__weak_ptr<_Tp>::operator=(__r);
 347           return *this;
 348         }
 349
 350       template<typename _Tp1>
 351         weak_ptr&
 352         operator=(const shared_ptr<_Tp1>& __r) // never throws
 353         {
 354           this->__weak_ptr<_Tp>::operator=(__r);
 355           return *this;
 356         }
 357
 358       shared_ptr<_Tp>
 359       lock() const // never throws
 360       {
 361 #ifdef __GTHREADS
 362         if (this->expired())
 363           return shared_ptr<_Tp>();
 364
 365         __try
 366           {
 367             return shared_ptr<_Tp>(*this);
 368           }
 369         __catch(const bad_weak_ptr&)
 370           {
 371             return shared_ptr<_Tp>();
 372           }
 373 #else
 374         return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
 375 #endif
 376       }
 377
 378       // Comparisons
 379       template<typename _Tp1>
 380         bool operator<(const weak_ptr<_Tp1>&) const = delete;
 381       template<typename _Tp1>
 382         bool operator<=(const weak_ptr<_Tp1>&) const = delete;
 383       template<typename _Tp1>
 384         bool operator>(const weak_ptr<_Tp1>&) const = delete;
 385       template<typename _Tp1>
 386         bool operator>=(const weak_ptr<_Tp1>&) const = delete;
 387     };
 388
 389   // 20.8.13.3.7 weak_ptr specialized algorithms.
 390   template<typename _Tp>
 391     inline void
 392     swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
 393     { __a.swap(__b); }
 394
 395
 396   /// Primary template owner_less
 397   template<typename _Tp>
 398     struct owner_less;
 399
 400   /// Partial specialization of owner_less for shared_ptr.
 401   template<typename _Tp>
 402     struct owner_less<shared_ptr<_Tp>>
 403     : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
 404     { };
 405
 406   /// Partial specialization of owner_less for weak_ptr.
 407   template<typename _Tp>
 408     struct owner_less<weak_ptr<_Tp>>
 409     : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
 410     { };
 411
 412   /**
 413    *  @brief Base class allowing use of member function shared_from_this.
 414    */
 415   template<typename _Tp>
 416     class enable_shared_from_this
 417     {
 418     protected:
 419       enable_shared_from_this() { }
 420
 421       enable_shared_from_this(const enable_shared_from_this&) { }
 422
 423       enable_shared_from_this&
 424       operator=(const enable_shared_from_this&)
 425       { return *this; }
 426
 427       ~enable_shared_from_this() { }
 428
 429     public:
 430       shared_ptr<_Tp>
 431       shared_from_this()
 432       { return shared_ptr<_Tp>(this->_M_weak_this); }
 433
 434       shared_ptr<const _Tp>
 435       shared_from_this() const
 436       { return shared_ptr<const _Tp>(this->_M_weak_this); }
 437
 438     private:
 439       template<typename _Tp1>
 440         void
 441         _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
 442         { _M_weak_this._M_assign(__p, __n); }
 443
 444       template<typename _Tp1>
 445         friend void
 446         __enable_shared_from_this_helper(const __shared_count<>& __pn,
 447                                          const enable_shared_from_this* __pe,
 448                                          const _Tp1* __px)
 449         {
 450           if (__pe != 0)
 451             __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
 452         }
 453
 454       mutable weak_ptr<_Tp>  _M_weak_this;
 455     };
 456
 457   /**
 458    *  @brief  Create an object that is owned by a shared_ptr.
 459    *  @param  __a     An allocator.
 460    *  @param  __args  Arguments for the @a _Tp object's constructor.
 461    *  @return A shared_ptr that owns the newly created object.
 462    *  @throw  An exception thrown from @a _Alloc::allocate or from the
 463    *          constructor of @a _Tp.
 464    *
 465    *  A copy of @a __a will be used to allocate memory for the shared_ptr
 466    *  and the new object.
 467    */
 468   template<typename _Tp, typename _Alloc, typename... _Args>
 469     inline shared_ptr<_Tp>
 470     allocate_shared(_Alloc __a, _Args&&... __args)
 471     {
 472       return shared_ptr<_Tp>(_Sp_make_shared_tag(), std::forward<_Alloc>(__a),
 473                              std::forward<_Args>(__args)...);
 474     }
 475
 476   /**
 477    *  @brief  Create an object that is owned by a shared_ptr.
 478    *  @param  __args  Arguments for the @a _Tp object's constructor.
 479    *  @return A shared_ptr that owns the newly created object.
 480    *  @throw  std::bad_alloc, or an exception thrown from the
 481    *          constructor of @a _Tp.
 482    */
 483   template<typename _Tp, typename... _Args>
 484     inline shared_ptr<_Tp>
 485     make_shared(_Args&&... __args)
 486     {
 487       typedef typename std::remove_const<_Tp>::type _Tp_nc;
 488       return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
 489                                   std::forward<_Args>(__args)...);
 490     }
 491
 492   // @} group pointer_abstractions
 493
 494 _GLIBCXX_END_NAMESPACE
 495
 496 #endif // _SHARED_PTR_H