boost/smart_ptr/shared_ptr.hpp

   1 #ifndef BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED
   3
   4 //
   5 //  shared_ptr.hpp
   6 //
   7 //  (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
   8 //  Copyright (c) 2001-2008 Peter Dimov
   9 //
  10 //  Distributed under the Boost Software License, Version 1.0. (See
  11 //  accompanying file LICENSE_1_0.txt or copy at
  12 //  http://www.boost.org/LICENSE_1_0.txt)
  13 //
  14 //  See http://www.boost.org/libs/smart_ptr/shared_ptr.htm for documentation.
  15 //
  16
  17 #include <boost/config.hpp>   // for broken compiler workarounds
  18
  19 #if defined(BOOST_NO_MEMBER_TEMPLATES) && !defined(BOOST_MSVC6_MEMBER_TEMPLATES)
  20 #include <boost/smart_ptr/detail/shared_ptr_nmt.hpp>
  21 #else
  22
  23 // In order to avoid circular dependencies with Boost.TR1
  24 // we make sure that our include of <memory> doesn't try to
  25 // pull in the TR1 headers: that's why we use this header
  26 // rather than including <memory> directly:
  27 #include <boost/config/no_tr1/memory.hpp>  // std::auto_ptr
  28
  29 #include <boost/assert.hpp>
  30 #include <boost/checked_delete.hpp>
  31 #include <boost/throw_exception.hpp>
  32 #include <boost/smart_ptr/detail/shared_count.hpp>
  33 #include <boost/detail/workaround.hpp>
  34 #include <boost/smart_ptr/detail/sp_convertible.hpp>
  35
  36 #if !defined(BOOST_SP_NO_ATOMIC_ACCESS)
  37 #include <boost/smart_ptr/detail/spinlock_pool.hpp>
  38 #include <boost/memory_order.hpp>
  39 #endif
  40
  41 #include <algorithm>            // for std::swap
  42 #include <functional>           // for std::less
  43 #include <typeinfo>             // for std::bad_cast
  44
  45 #if !defined(BOOST_NO_IOSTREAM)
  46 #if !defined(BOOST_NO_IOSFWD)
  47 #include <iosfwd>               // for std::basic_ostream
  48 #else
  49 #include <ostream>
  50 #endif
  51 #endif
  52
  53 #ifdef BOOST_MSVC  // moved here to work around VC++ compiler crash
  54 # pragma warning(push)
  55 # pragma warning(disable:4284) // odd return type for operator->
  56 #endif
  57
  58 namespace boost
  59 {
  60
  61 template<class T> class shared_ptr;
  62 template<class T> class weak_ptr;
  63 template<class T> class enable_shared_from_this;
  64 template<class T> class enable_shared_from_this2;
  65
  66 namespace detail
  67 {
  68
  69 struct static_cast_tag {};
  70 struct const_cast_tag {};
  71 struct dynamic_cast_tag {};
  72 struct polymorphic_cast_tag {};
  73
  74 template<class T> struct shared_ptr_traits
  75 {
  76     typedef T & reference;
  77 };
  78
  79 template<> struct shared_ptr_traits<void>
  80 {
  81     typedef void reference;
  82 };
  83
  84 #if !defined(BOOST_NO_CV_VOID_SPECIALIZATIONS)
  85
  86 template<> struct shared_ptr_traits<void const>
  87 {
  88     typedef void reference;
  89 };
  90
  91 template<> struct shared_ptr_traits<void volatile>
  92 {
  93     typedef void reference;
  94 };
  95
  96 template<> struct shared_ptr_traits<void const volatile>
  97 {
  98     typedef void reference;
  99 };
 100
 101 #endif
 102
 103 // enable_shared_from_this support
 104
 105 template< class X, class Y, class T > inline void sp_enable_shared_from_this( boost::shared_ptr<X> const * ppx, Y const * py, boost::enable_shared_from_this< T > const * pe )
 106 {
 107     if( pe != 0 )
 108     {
 109         pe->_internal_accept_owner( ppx, const_cast< Y* >( py ) );
 110     }
 111 }
 112
 113 template< class X, class Y, class T > inline void sp_enable_shared_from_this( boost::shared_ptr<X> * ppx, Y const * py, boost::enable_shared_from_this2< T > const * pe )
 114 {
 115     if( pe != 0 )
 116     {
 117         pe->_internal_accept_owner( ppx, const_cast< Y* >( py ) );
 118     }
 119 }
 120
 121 #ifdef _MANAGED
 122
 123 // Avoid C4793, ... causes native code generation
 124
 125 struct sp_any_pointer
 126 {
 127     template<class T> sp_any_pointer( T* ) {}
 128 };
 129
 130 inline void sp_enable_shared_from_this( sp_any_pointer, sp_any_pointer, sp_any_pointer )
 131 {
 132 }
 133
 134 #else // _MANAGED
 135
 136 inline void sp_enable_shared_from_this( ... )
 137 {
 138 }
 139
 140 #endif // _MANAGED
 141
 142 #if !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined( BOOST_NO_AUTO_PTR )
 143
 144 // rvalue auto_ptr support based on a technique by Dave Abrahams
 145
 146 template< class T, class R > struct sp_enable_if_auto_ptr
 147 {
 148 };
 149
 150 template< class T, class R > struct sp_enable_if_auto_ptr< std::auto_ptr< T >, R >
 151 {
 152     typedef R type;
 153 };
 154
 155 #endif
 156
 157 } // namespace detail
 158
 159
 160 //
 161 //  shared_ptr
 162 //
 163 //  An enhanced relative of scoped_ptr with reference counted copy semantics.
 164 //  The object pointed to is deleted when the last shared_ptr pointing to it
 165 //  is destroyed or reset.
 166 //
 167
 168 template<class T> class shared_ptr
 169 {
 170 private:
 171
 172     // Borland 5.5.1 specific workaround
 173     typedef shared_ptr<T> this_type;
 174
 175 public:
 176
 177     typedef T element_type;
 178     typedef T value_type;
 179     typedef T * pointer;
 180     typedef typename boost::detail::shared_ptr_traits<T>::reference reference;
 181
 182     shared_ptr(): px(0), pn() // never throws in 1.30+
 183     {
 184     }
 185
 186     template<class Y>
 187     explicit shared_ptr( Y * p ): px( p ), pn( p ) // Y must be complete
 188     {
 189         boost::detail::sp_enable_shared_from_this( this, p, p );
 190     }
 191
 192     //
 193     // Requirements: D's copy constructor must not throw
 194     //
 195     // shared_ptr will release p by calling d(p)
 196     //
 197
 198     template<class Y, class D> shared_ptr(Y * p, D d): px(p), pn(p, d)
 199     {
 200         boost::detail::sp_enable_shared_from_this( this, p, p );
 201     }
 202
 203     // As above, but with allocator. A's copy constructor shall not throw.
 204
 205     template<class Y, class D, class A> shared_ptr( Y * p, D d, A a ): px( p ), pn( p, d, a )
 206     {
 207         boost::detail::sp_enable_shared_from_this( this, p, p );
 208     }
 209
 210 //  generated copy constructor, destructor are fine
 211
 212     template<class Y>
 213     explicit shared_ptr(weak_ptr<Y> const & r): pn(r.pn) // may throw
 214     {
 215         // it is now safe to copy r.px, as pn(r.pn) did not throw
 216         px = r.px;
 217     }
 218
 219     template<class Y>
 220     shared_ptr( weak_ptr<Y> const & r, boost::detail::sp_nothrow_tag ): px( 0 ), pn( r.pn, boost::detail::sp_nothrow_tag() ) // never throws
 221     {
 222         if( !pn.empty() )
 223         {
 224             px = r.px;
 225         }
 226     }
 227
 228     template<class Y>
 229 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
 230
 231     shared_ptr( shared_ptr<Y> const & r, typename detail::sp_enable_if_convertible<Y,T>::type = detail::sp_empty() )
 232
 233 #else
 234
 235     shared_ptr( shared_ptr<Y> const & r )
 236
 237 #endif
 238     : px( r.px ), pn( r.pn ) // never throws
 239     {
 240     }
 241
 242     // aliasing
 243     template< class Y >
 244     shared_ptr( shared_ptr<Y> const & r, T * p ): px( p ), pn( r.pn ) // never throws
 245     {
 246     }
 247
 248     template<class Y>
 249     shared_ptr(shared_ptr<Y> const & r, boost::detail::static_cast_tag): px(static_cast<element_type *>(r.px)), pn(r.pn)
 250     {
 251     }
 252
 253     template<class Y>
 254     shared_ptr(shared_ptr<Y> const & r, boost::detail::const_cast_tag): px(const_cast<element_type *>(r.px)), pn(r.pn)
 255     {
 256     }
 257
 258     template<class Y>
 259     shared_ptr(shared_ptr<Y> const & r, boost::detail::dynamic_cast_tag): px(dynamic_cast<element_type *>(r.px)), pn(r.pn)
 260     {
 261         if(px == 0) // need to allocate new counter -- the cast failed
 262         {
 263             pn = boost::detail::shared_count();
 264         }
 265     }
 266
 267     template<class Y>
 268     shared_ptr(shared_ptr<Y> const & r, boost::detail::polymorphic_cast_tag): px(dynamic_cast<element_type *>(r.px)), pn(r.pn)
 269     {
 270         if(px == 0)
 271         {
 272             boost::throw_exception(std::bad_cast());
 273         }
 274     }
 275
 276 #ifndef BOOST_NO_AUTO_PTR
 277
 278     template<class Y>
 279     explicit shared_ptr(std::auto_ptr<Y> & r): px(r.get()), pn()
 280     {
 281         Y * tmp = r.get();
 282         pn = boost::detail::shared_count(r);
 283         boost::detail::sp_enable_shared_from_this( this, tmp, tmp );
 284     }
 285
 286 #if !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
 287
 288     template<class Ap>
 289     explicit shared_ptr( Ap r, typename boost::detail::sp_enable_if_auto_ptr<Ap, int>::type = 0 ): px( r.get() ), pn()
 290     {
 291         typename Ap::element_type * tmp = r.get();
 292         pn = boost::detail::shared_count( r );
 293         boost::detail::sp_enable_shared_from_this( this, tmp, tmp );
 294     }
 295
 296
 297 #endif // BOOST_NO_SFINAE, BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 298
 299 #endif // BOOST_NO_AUTO_PTR
 300
 301     // assignment
 302
 303     shared_ptr & operator=( shared_ptr const & r ) // never throws
 304     {
 305         this_type(r).swap(*this);
 306         return *this;
 307     }
 308
 309 #if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1400)
 310
 311     template<class Y>
 312     shared_ptr & operator=(shared_ptr<Y> const & r) // never throws
 313     {
 314         this_type(r).swap(*this);
 315         return *this;
 316     }
 317
 318 #endif
 319
 320 #ifndef BOOST_NO_AUTO_PTR
 321
 322     template<class Y>
 323     shared_ptr & operator=( std::auto_ptr<Y> & r )
 324     {
 325         this_type(r).swap(*this);
 326         return *this;
 327     }
 328
 329 #if !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
 330
 331     template<class Ap>
 332     typename boost::detail::sp_enable_if_auto_ptr< Ap, shared_ptr & >::type operator=( Ap r )
 333     {
 334         this_type( r ).swap( *this );
 335         return *this;
 336     }
 337
 338
 339 #endif // BOOST_NO_SFINAE, BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 340
 341 #endif // BOOST_NO_AUTO_PTR
 342
 343 // Move support
 344
 345 #if defined( BOOST_HAS_RVALUE_REFS )
 346
 347     shared_ptr( shared_ptr && r ): px( r.px ), pn() // never throws
 348     {
 349         pn.swap( r.pn );
 350         r.px = 0;
 351     }
 352
 353     template<class Y>
 354 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
 355
 356     shared_ptr( shared_ptr<Y> && r, typename detail::sp_enable_if_convertible<Y,T>::type = detail::sp_empty() )
 357
 358 #else
 359
 360     shared_ptr( shared_ptr<Y> && r )
 361
 362 #endif
 363     : px( r.px ), pn() // never throws
 364     {
 365         pn.swap( r.pn );
 366         r.px = 0;
 367     }
 368
 369     shared_ptr & operator=( shared_ptr && r ) // never throws
 370     {
 371         this_type( std::move( r ) ).swap( *this );
 372         return *this;
 373     }
 374
 375     template<class Y>
 376     shared_ptr & operator=( shared_ptr<Y> && r ) // never throws
 377     {
 378         this_type( std::move( r ) ).swap( *this );
 379         return *this;
 380     }
 381
 382 #endif
 383
 384     void reset() // never throws in 1.30+
 385     {
 386         this_type().swap(*this);
 387     }
 388
 389     template<class Y> void reset(Y * p) // Y must be complete
 390     {
 391         BOOST_ASSERT(p == 0 || p != px); // catch self-reset errors
 392         this_type(p).swap(*this);
 393     }
 394
 395     template<class Y, class D> void reset( Y * p, D d )
 396     {
 397         this_type( p, d ).swap( *this );
 398     }
 399
 400     template<class Y, class D, class A> void reset( Y * p, D d, A a )
 401     {
 402         this_type( p, d, a ).swap( *this );
 403     }
 404
 405     template<class Y> void reset( shared_ptr<Y> const & r, T * p )
 406     {
 407         this_type( r, p ).swap( *this );
 408     }
 409
 410     reference operator* () const // never throws
 411     {
 412         BOOST_ASSERT(px != 0);
 413         return *px;
 414     }
 415
 416     T * operator-> () const // never throws
 417     {
 418         BOOST_ASSERT(px != 0);
 419         return px;
 420     }
 421
 422     T * get() const // never throws
 423     {
 424         return px;
 425     }
 426
 427 // implicit conversion to "bool"
 428 #include <boost/smart_ptr/detail/operator_bool.hpp>
 429
 430     bool unique() const // never throws
 431     {
 432         return pn.unique();
 433     }
 434
 435     long use_count() const // never throws
 436     {
 437         return pn.use_count();
 438     }
 439
 440     void swap(shared_ptr<T> & other) // never throws
 441     {
 442         std::swap(px, other.px);
 443         pn.swap(other.pn);
 444     }
 445
 446     template<class Y> bool _internal_less(shared_ptr<Y> const & rhs) const
 447     {
 448         return pn < rhs.pn;
 449     }
 450
 451     void * _internal_get_deleter( detail::sp_typeinfo const & ti ) const
 452     {
 453         return pn.get_deleter( ti );
 454     }
 455
 456     bool _internal_equiv( shared_ptr const & r ) const
 457     {
 458         return px == r.px && pn == r.pn;
 459     }
 460
 461 // Tasteless as this may seem, making all members public allows member templates
 462 // to work in the absence of member template friends. (Matthew Langston)
 463
 464 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
 465
 466 private:
 467
 468     template<class Y> friend class shared_ptr;
 469     template<class Y> friend class weak_ptr;
 470
 471
 472 #endif
 473
 474     T * px;                     // contained pointer
 475     boost::detail::shared_count pn;    // reference counter
 476
 477 };  // shared_ptr
 478
 479 template<class T, class U> inline bool operator==(shared_ptr<T> const & a, shared_ptr<U> const & b)
 480 {
 481     return a.get() == b.get();
 482 }
 483
 484 template<class T, class U> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<U> const & b)
 485 {
 486     return a.get() != b.get();
 487 }
 488
 489 #if __GNUC__ == 2 && __GNUC_MINOR__ <= 96
 490
 491 // Resolve the ambiguity between our op!= and the one in rel_ops
 492
 493 template<class T> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<T> const & b)
 494 {
 495     return a.get() != b.get();
 496 }
 497
 498 #endif
 499
 500 template<class T, class U> inline bool operator<(shared_ptr<T> const & a, shared_ptr<U> const & b)
 501 {
 502     return a._internal_less(b);
 503 }
 504
 505 template<class T> inline void swap(shared_ptr<T> & a, shared_ptr<T> & b)
 506 {
 507     a.swap(b);
 508 }
 509
 510 template<class T, class U> shared_ptr<T> static_pointer_cast(shared_ptr<U> const & r)
 511 {
 512     return shared_ptr<T>(r, boost::detail::static_cast_tag());
 513 }
 514
 515 template<class T, class U> shared_ptr<T> const_pointer_cast(shared_ptr<U> const & r)
 516 {
 517     return shared_ptr<T>(r, boost::detail::const_cast_tag());
 518 }
 519
 520 template<class T, class U> shared_ptr<T> dynamic_pointer_cast(shared_ptr<U> const & r)
 521 {
 522     return shared_ptr<T>(r, boost::detail::dynamic_cast_tag());
 523 }
 524
 525 // shared_*_cast names are deprecated. Use *_pointer_cast instead.
 526
 527 template<class T, class U> shared_ptr<T> shared_static_cast(shared_ptr<U> const & r)
 528 {
 529     return shared_ptr<T>(r, boost::detail::static_cast_tag());
 530 }
 531
 532 template<class T, class U> shared_ptr<T> shared_dynamic_cast(shared_ptr<U> const & r)
 533 {
 534     return shared_ptr<T>(r, boost::detail::dynamic_cast_tag());
 535 }
 536
 537 template<class T, class U> shared_ptr<T> shared_polymorphic_cast(shared_ptr<U> const & r)
 538 {
 539     return shared_ptr<T>(r, boost::detail::polymorphic_cast_tag());
 540 }
 541
 542 template<class T, class U> shared_ptr<T> shared_polymorphic_downcast(shared_ptr<U> const & r)
 543 {
 544     BOOST_ASSERT(dynamic_cast<T *>(r.get()) == r.get());
 545     return shared_static_cast<T>(r);
 546 }
 547
 548 // get_pointer() enables boost::mem_fn to recognize shared_ptr
 549
 550 template<class T> inline T * get_pointer(shared_ptr<T> const & p)
 551 {
 552     return p.get();
 553 }
 554
 555 // operator<<
 556
 557 #if !defined(BOOST_NO_IOSTREAM)
 558
 559 #if defined(BOOST_NO_TEMPLATED_IOSTREAMS) || ( defined(__GNUC__) &&  (__GNUC__ < 3) )
 560
 561 template<class Y> std::ostream & operator<< (std::ostream & os, shared_ptr<Y> const & p)
 562 {
 563     os << p.get();
 564     return os;
 565 }
 566
 567 #else
 568
 569 // in STLport's no-iostreams mode no iostream symbols can be used
 570 #ifndef _STLP_NO_IOSTREAMS
 571
 572 # if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300 && __SGI_STL_PORT)
 573 // MSVC6 has problems finding std::basic_ostream through the using declaration in namespace _STL
 574 using std::basic_ostream;
 575 template<class E, class T, class Y> basic_ostream<E, T> & operator<< (basic_ostream<E, T> & os, shared_ptr<Y> const & p)
 576 # else
 577 template<class E, class T, class Y> std::basic_ostream<E, T> & operator<< (std::basic_ostream<E, T> & os, shared_ptr<Y> const & p)
 578 # endif
 579 {
 580     os << p.get();
 581     return os;
 582 }
 583
 584 #endif // _STLP_NO_IOSTREAMS
 585
 586 #endif // __GNUC__ < 3
 587
 588 #endif // !defined(BOOST_NO_IOSTREAM)
 589
 590 // get_deleter
 591
 592 #if ( defined(__GNUC__) && BOOST_WORKAROUND(__GNUC__, < 3) ) || \
 593     ( defined(__EDG_VERSION__) && BOOST_WORKAROUND(__EDG_VERSION__, <= 238) ) || \
 594     ( defined(__HP_aCC) && BOOST_WORKAROUND(__HP_aCC, <= 33500) )
 595
 596 // g++ 2.9x doesn't allow static_cast<X const *>(void *)
 597 // apparently EDG 2.38 and HP aCC A.03.35 also don't accept it
 598
 599 template<class D, class T> D * get_deleter(shared_ptr<T> const & p)
 600 {
 601     void const * q = p._internal_get_deleter(BOOST_SP_TYPEID(D));
 602     return const_cast<D *>(static_cast<D const *>(q));
 603 }
 604
 605 #else
 606
 607 template<class D, class T> D * get_deleter(shared_ptr<T> const & p)
 608 {
 609     return static_cast<D *>(p._internal_get_deleter(BOOST_SP_TYPEID(D)));
 610 }
 611
 612 #endif
 613
 614 // atomic access
 615
 616 #if !defined(BOOST_SP_NO_ATOMIC_ACCESS)
 617
 618 template<class T> inline bool atomic_is_lock_free( shared_ptr<T> const * /*p*/ )
 619 {
 620     return false;
 621 }
 622
 623 template<class T> shared_ptr<T> atomic_load( shared_ptr<T> const * p )
 624 {
 625     boost::detail::spinlock_pool<2>::scoped_lock lock( p );
 626     return *p;
 627 }
 628
 629 template<class T> inline shared_ptr<T> atomic_load_explicit( shared_ptr<T> const * p, memory_order /*mo*/ )
 630 {
 631     return atomic_load( p );
 632 }
 633
 634 template<class T> void atomic_store( shared_ptr<T> * p, shared_ptr<T> r )
 635 {
 636     boost::detail::spinlock_pool<2>::scoped_lock lock( p );
 637     p->swap( r );
 638 }
 639
 640 template<class T> inline void atomic_store_explicit( shared_ptr<T> * p, shared_ptr<T> r, memory_order /*mo*/ )
 641 {
 642     atomic_store( p, r ); // std::move( r )
 643 }
 644
 645 template<class T> shared_ptr<T> atomic_exchange( shared_ptr<T> * p, shared_ptr<T> r )
 646 {
 647     boost::detail::spinlock & sp = boost::detail::spinlock_pool<2>::spinlock_for( p );
 648
 649     sp.lock();
 650     p->swap( r );
 651     sp.unlock();
 652
 653     return r; // return std::move( r )
 654 }
 655
 656 template<class T> shared_ptr<T> atomic_exchange_explicit( shared_ptr<T> * p, shared_ptr<T> r, memory_order /*mo*/ )
 657 {
 658     return atomic_exchange( p, r ); // std::move( r )
 659 }
 660
 661 template<class T> bool atomic_compare_exchange( shared_ptr<T> * p, shared_ptr<T> * v, shared_ptr<T> w )
 662 {
 663     boost::detail::spinlock & sp = boost::detail::spinlock_pool<2>::spinlock_for( p );
 664
 665     sp.lock();
 666
 667     if( p->_internal_equiv( *v ) )
 668     {
 669         p->swap( w );
 670
 671         sp.unlock();
 672
 673         return true;
 674     }
 675     else
 676     {
 677         shared_ptr<T> tmp( *p );
 678
 679         sp.unlock();
 680
 681         tmp.swap( *v );
 682         return false;
 683     }
 684 }
 685
 686 template<class T> inline bool atomic_compare_exchange_explicit( shared_ptr<T> * p, shared_ptr<T> * v, shared_ptr<T> w, memory_order /*success*/, memory_order /*failure*/ )
 687 {
 688     return atomic_compare_exchange( p, v, w ); // std::move( w )
 689 }
 690
 691 #endif
 692
 693 } // namespace boost
 694
 695 #ifdef BOOST_MSVC
 696 # pragma warning(pop)
 697 #endif
 698
 699 #endif  // #if defined(BOOST_NO_MEMBER_TEMPLATES) && !defined(BOOST_MSVC6_MEMBER_TEMPLATES)
 700
 701 #endif  // #ifndef BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED