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

   1 // shared_ptr and weak_ptr implementation -*- C++ -*-
   2
   3 // Copyright (C) 2007, 2008, 2009 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 #ifndef __GXX_EXPERIMENTAL_CXX0X__
  53 # include <c++0x_warning.h>
  54 #endif
  55
  56 #include <bits/shared_ptr_base.h>
  57
  58 _GLIBCXX_BEGIN_NAMESPACE(std)
  59
  60   /**
  61    * @addtogroup pointer_abstractions
  62    * @{
  63    */
  64
  65   /// 2.2.3.7 shared_ptr I/O
  66   template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
  67     std::basic_ostream<_Ch, _Tr>&
  68     operator<<(std::basic_ostream<_Ch, _Tr>& __os,
  69                const __shared_ptr<_Tp, _Lp>& __p)
  70     {
  71       __os << __p.get();
  72       return __os;
  73     }
  74
  75   /// 2.2.3.10 shared_ptr get_deleter (experimental)
  76   template<typename _Del, typename _Tp, _Lock_policy _Lp>
  77     inline _Del*
  78     get_deleter(const __shared_ptr<_Tp, _Lp>& __p)
  79     { return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); }
  80
  81
  82   /**
  83    *  @brief  A smart pointer with reference-counted copy semantics.
  84    *
  85    *  The object pointed to is deleted when the last shared_ptr pointing to
  86    *  it is destroyed or reset.
  87   */
  88   template<typename _Tp>
  89     class shared_ptr : public __shared_ptr<_Tp>
  90     {
  91     public:
  92       /**
  93        *  @brief  Construct an empty %shared_ptr.
  94        *  @post   use_count()==0 && get()==0
  95        */
  96       shared_ptr() : __shared_ptr<_Tp>() { }
  97
  98       /**
  99        *  @brief  Construct a %shared_ptr that owns the pointer @a __p.
 100        *  @param  __p  A pointer that is convertible to element_type*.
 101        *  @post   use_count() == 1 && get() == __p
 102        *  @throw  std::bad_alloc, in which case @c delete @a __p is called.
 103        */
 104       template<typename _Tp1>
 105         explicit shared_ptr(_Tp1* __p) : __shared_ptr<_Tp>(__p) { }
 106
 107       /**
 108        *  @brief  Construct a %shared_ptr that owns the pointer @a __p
 109        *          and the deleter @a __d.
 110        *  @param  __p  A pointer.
 111        *  @param  __d  A deleter.
 112        *  @post   use_count() == 1 && get() == __p
 113        *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
 114        *
 115        *  Requirements: _Deleter's copy constructor and destructor must
 116        *  not throw
 117        *
 118        *  __shared_ptr will release __p by calling __d(__p)
 119        */
 120         template<typename _Tp1, typename _Deleter>
 121         shared_ptr(_Tp1* __p, _Deleter __d) : __shared_ptr<_Tp>(__p, __d) { }
 122
 123       /**
 124        *  @brief  Construct a %shared_ptr that owns the pointer @a __p
 125        *          and the deleter @a __d.
 126        *  @param  __p  A pointer.
 127        *  @param  __d  A deleter.
 128        *  @param  __a  An allocator.
 129        *  @post   use_count() == 1 && get() == __p
 130        *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
 131        *
 132        *  Requirements: _Deleter's copy constructor and destructor must
 133        *  not throw _Alloc's copy constructor and destructor must not
 134        *  throw.
 135        *
 136        *  __shared_ptr will release __p by calling __d(__p)
 137        */
 138       template<typename _Tp1, typename _Deleter, typename _Alloc>
 139         shared_ptr(_Tp1* __p, _Deleter __d, const _Alloc& __a)
 140         : __shared_ptr<_Tp>(__p, __d, __a) { }
 141
 142       // Aliasing constructor
 143
 144       /**
 145        *  @brief  Constructs a %shared_ptr instance that stores @a __p
 146        *          and shares ownership with @a __r.
 147        *  @param  __r  A %shared_ptr.
 148        *  @param  __p  A pointer that will remain valid while @a *__r is valid.
 149        *  @post   get() == __p && use_count() == __r.use_count()
 150        *
 151        *  This can be used to construct a @c shared_ptr to a sub-object
 152        *  of an object managed by an existing @c shared_ptr.
 153        *
 154        * @code
 155        * shared_ptr< pair<int,int> > pii(new pair<int,int>());
 156        * shared_ptr<int> pi(pii, &pii->first);
 157        * assert(pii.use_count() == 2);
 158        * @endcode
 159        */
 160       template<typename _Tp1>
 161         shared_ptr(const shared_ptr<_Tp1>& __r, _Tp* __p)
 162         : __shared_ptr<_Tp>(__r, __p) { }
 163
 164       /**
 165        *  @brief  If @a __r is empty, constructs an empty %shared_ptr;
 166        *          otherwise construct a %shared_ptr that shares ownership
 167        *          with @a __r.
 168        *  @param  __r  A %shared_ptr.
 169        *  @post   get() == __r.get() && use_count() == __r.use_count()
 170        */
 171       template<typename _Tp1>
 172         shared_ptr(const shared_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { }
 173
 174       /**
 175        *  @brief  Move-constructs a %shared_ptr instance from @a __r.
 176        *  @param  __r  A %shared_ptr rvalue.
 177        *  @post   *this contains the old value of @a __r, @a __r is empty.
 178        */
 179       shared_ptr(shared_ptr&& __r)
 180       : __shared_ptr<_Tp>(std::move(__r)) { }
 181
 182       /**
 183        *  @brief  Move-constructs a %shared_ptr instance from @a __r.
 184        *  @param  __r  A %shared_ptr rvalue.
 185        *  @post   *this contains the old value of @a __r, @a __r is empty.
 186        */
 187       template<typename _Tp1>
 188         shared_ptr(shared_ptr<_Tp1>&& __r)
 189         : __shared_ptr<_Tp>(std::move(__r)) { }
 190
 191       /**
 192        *  @brief  Constructs a %shared_ptr that shares ownership with @a __r
 193        *          and stores a copy of the pointer stored in @a __r.
 194        *  @param  __r  A weak_ptr.
 195        *  @post   use_count() == __r.use_count()
 196        *  @throw  bad_weak_ptr when __r.expired(),
 197        *          in which case the constructor has no effect.
 198        */
 199       template<typename _Tp1>
 200         explicit shared_ptr(const weak_ptr<_Tp1>& __r)
 201         : __shared_ptr<_Tp>(__r) { }
 202
 203 #if _GLIBCXX_DEPRECATED
 204       template<typename _Tp1>
 205         explicit
 206         shared_ptr(std::auto_ptr<_Tp1>&& __r)
 207         : __shared_ptr<_Tp>(std::move(__r)) { }
 208 #endif
 209
 210       template<typename _Tp1, typename _Del>
 211         explicit shared_ptr(const std::unique_ptr<_Tp1, _Del>&) = delete;
 212
 213       template<typename _Tp1, typename _Del>
 214         explicit shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
 215         : __shared_ptr<_Tp>(std::move(__r)) { }
 216
 217       template<typename _Tp1>
 218         shared_ptr&
 219         operator=(const shared_ptr<_Tp1>& __r) // never throws
 220         {
 221           this->__shared_ptr<_Tp>::operator=(__r);
 222           return *this;
 223         }
 224
 225 #if _GLIBCXX_DEPRECATED
 226       template<typename _Tp1>
 227         shared_ptr&
 228         operator=(std::auto_ptr<_Tp1>&& __r)
 229         {
 230           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 231           return *this;
 232         }
 233 #endif
 234
 235       shared_ptr&
 236       operator=(shared_ptr&& __r)
 237       {
 238         this->__shared_ptr<_Tp>::operator=(std::move(__r));
 239         return *this;
 240       }
 241
 242       template<class _Tp1>
 243         shared_ptr&
 244         operator=(shared_ptr<_Tp1>&& __r)
 245         {
 246           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 247           return *this;
 248         }
 249
 250       template<typename _Tp1, typename _Del>
 251         shared_ptr&
 252         operator=(const std::unique_ptr<_Tp1, _Del>& __r) = delete;
 253
 254       template<typename _Tp1, typename _Del>
 255         shared_ptr&
 256         operator=(std::unique_ptr<_Tp1, _Del>&& __r)
 257         {
 258           this->__shared_ptr<_Tp>::operator=(std::move(__r));
 259           return *this;
 260         }
 261
 262     private:
 263       // This constructor is non-standard, it is used by allocate_shared.
 264       template<typename _Alloc, typename... _Args>
 265         shared_ptr(_Sp_make_shared_tag __tag, _Alloc __a, _Args&&... __args)
 266         : __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
 267         { }
 268
 269       template<typename _Tp1, typename _Alloc, typename... _Args>
 270         friend shared_ptr<_Tp1>
 271         allocate_shared(_Alloc __a, _Args&&... __args);
 272     };
 273
 274   // 20.8.13.2.7 shared_ptr comparisons
 275   template<typename _Tp1, typename _Tp2>
 276     inline bool
 277     operator==(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 278     { return __a.get() == __b.get(); }
 279
 280   template<typename _Tp1, typename _Tp2>
 281     inline bool
 282     operator!=(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 283     { return __a.get() != __b.get(); }
 284
 285   template<typename _Tp1, typename _Tp2>
 286     inline bool
 287     operator<(const shared_ptr<_Tp1>& __a, const shared_ptr<_Tp2>& __b)
 288     { return __a.get() < __b.get(); }
 289
 290   template<typename _Tp>
 291     struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
 292     { };
 293
 294   // 20.8.13.2.9 shared_ptr specialized algorithms.
 295   template<typename _Tp>
 296     inline void
 297     swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b)
 298     { __a.swap(__b); }
 299
 300   // 20.8.13.2.10 shared_ptr casts.
 301   template<typename _Tp, typename _Tp1>
 302     inline shared_ptr<_Tp>
 303     static_pointer_cast(const shared_ptr<_Tp1>& __r)
 304     { return shared_ptr<_Tp>(__r, static_cast<_Tp*>(__r.get())); }
 305
 306   template<typename _Tp, typename _Tp1>
 307     inline shared_ptr<_Tp>
 308     const_pointer_cast(const shared_ptr<_Tp1>& __r)
 309     { return shared_ptr<_Tp>(__r, const_cast<_Tp*>(__r.get())); }
 310
 311   template<typename _Tp, typename _Tp1>
 312     inline shared_ptr<_Tp>
 313     dynamic_pointer_cast(const shared_ptr<_Tp1>& __r)
 314     {
 315       if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
 316         return shared_ptr<_Tp>(__r, __p);
 317       return shared_ptr<_Tp>();
 318     }
 319
 320
 321   /**
 322    *  @brief  A smart pointer with weak semantics.
 323    *
 324    *  With forwarding constructors and assignment operators.
 325    */
 326   template<typename _Tp>
 327     class weak_ptr : public __weak_ptr<_Tp>
 328     {
 329     public:
 330       weak_ptr() : __weak_ptr<_Tp>() { }
 331
 332       template<typename _Tp1>
 333         weak_ptr(const weak_ptr<_Tp1>& __r)
 334         : __weak_ptr<_Tp>(__r) { }
 335
 336       template<typename _Tp1>
 337         weak_ptr(const shared_ptr<_Tp1>& __r)
 338         : __weak_ptr<_Tp>(__r) { }
 339
 340       template<typename _Tp1>
 341         weak_ptr&
 342         operator=(const weak_ptr<_Tp1>& __r) // never throws
 343         {
 344           this->__weak_ptr<_Tp>::operator=(__r);
 345           return *this;
 346         }
 347
 348       template<typename _Tp1>
 349         weak_ptr&
 350         operator=(const shared_ptr<_Tp1>& __r) // never throws
 351         {
 352           this->__weak_ptr<_Tp>::operator=(__r);
 353           return *this;
 354         }
 355
 356       shared_ptr<_Tp>
 357       lock() const // never throws
 358       {
 359 #ifdef __GTHREADS
 360         if (this->expired())
 361           return shared_ptr<_Tp>();
 362
 363         __try
 364           {
 365             return shared_ptr<_Tp>(*this);
 366           }
 367         __catch(const bad_weak_ptr&)
 368           {
 369             return shared_ptr<_Tp>();
 370           }
 371 #else
 372         return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
 373 #endif
 374       }
 375
 376       // Comparisons
 377       template<typename _Tp1>
 378         bool operator<(const weak_ptr<_Tp1>&) const = delete;
 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     };
 386
 387   // 20.8.13.3.7 weak_ptr specialized algorithms.
 388   template<typename _Tp>
 389     inline void
 390     swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b)
 391     { __a.swap(__b); }
 392
 393
 394   /// Primary template owner_less
 395   template<typename _Tp>
 396     struct owner_less;
 397
 398   /// Partial specialization of owner_less for shared_ptr.
 399   template<typename _Tp>
 400     struct owner_less<shared_ptr<_Tp>>
 401     : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
 402     { };
 403
 404   /// Partial specialization of owner_less for weak_ptr.
 405   template<typename _Tp>
 406     struct owner_less<weak_ptr<_Tp>>
 407     : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
 408     { };
 409
 410   /**
 411    *  @brief Base class allowing use of member function shared_from_this.
 412    */
 413   template<typename _Tp>
 414     class enable_shared_from_this
 415     {
 416     protected:
 417       enable_shared_from_this() { }
 418
 419       enable_shared_from_this(const enable_shared_from_this&) { }
 420
 421       enable_shared_from_this&
 422       operator=(const enable_shared_from_this&)
 423       { return *this; }
 424
 425       ~enable_shared_from_this() { }
 426
 427     public:
 428       shared_ptr<_Tp>
 429       shared_from_this()
 430       { return shared_ptr<_Tp>(this->_M_weak_this); }
 431
 432       shared_ptr<const _Tp>
 433       shared_from_this() const
 434       { return shared_ptr<const _Tp>(this->_M_weak_this); }
 435
 436     private:
 437       template<typename _Tp1>
 438         void
 439         _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const
 440         { _M_weak_this._M_assign(__p, __n); }
 441
 442       template<typename _Tp1>
 443         friend void
 444         __enable_shared_from_this_helper(const __shared_count<>& __pn,
 445                                          const enable_shared_from_this* __pe,
 446                                          const _Tp1* __px)
 447         {
 448           if (__pe != 0)
 449             __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
 450         }
 451
 452       mutable weak_ptr<_Tp>  _M_weak_this;
 453     };
 454
 455   /**
 456    *  @brief  Create an object that is owned by a shared_ptr.
 457    *  @param  __a     An allocator.
 458    *  @param  __args  Arguments for the @a _Tp object's constructor.
 459    *  @return A shared_ptr that owns the newly created object.
 460    *  @throw  An exception thrown from @a _Alloc::allocate or from the
 461    *          constructor of @a _Tp.
 462    *
 463    *  A copy of @a __a will be used to allocate memory for the shared_ptr
 464    *  and the new object.
 465    */
 466   template<typename _Tp, typename _Alloc, typename... _Args>
 467     inline shared_ptr<_Tp>
 468     allocate_shared(_Alloc __a, _Args&&... __args)
 469     {
 470       return shared_ptr<_Tp>(_Sp_make_shared_tag(), std::forward<_Alloc>(__a),
 471                              std::forward<_Args>(__args)...);
 472     }
 473
 474   /**
 475    *  @brief  Create an object that is owned by a shared_ptr.
 476    *  @param  __args  Arguments for the @a _Tp object's constructor.
 477    *  @return A shared_ptr that owns the newly created object.
 478    *  @throw  std::bad_alloc, or an exception thrown from the
 479    *          constructor of @a _Tp.
 480    */
 481   template<typename _Tp, typename... _Args>
 482     inline shared_ptr<_Tp>
 483     make_shared(_Args&&... __args)
 484     {
 485       typedef typename std::remove_const<_Tp>::type _Tp_nc;
 486       return allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
 487                                   std::forward<_Args>(__args)...);
 488     }
 489
 490   // @} group pointer_abstractions
 491
 492 _GLIBCXX_END_NAMESPACE
 493
 494 #endif // _SHARED_PTR_H