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

   1 // unique_ptr implementation -*- C++ -*-
   2
   3 // Copyright (C) 2008-2018 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 /** @file bits/unique_ptr.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{memory}
  28  */
  29
  30 #ifndef _UNIQUE_PTR_H
  31 #define _UNIQUE_PTR_H 1
  32
  33 #include <bits/c++config.h>
  34 #include <debug/assertions.h>
  35 #include <type_traits>
  36 #include <utility>
  37 #include <tuple>
  38 #include <bits/stl_function.h>
  39 #include <bits/functional_hash.h>
  40
  41 namespace std _GLIBCXX_VISIBILITY(default)
  42 {
  43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45   /**
  46    * @addtogroup pointer_abstractions
  47    * @{
  48    */
  49
  50 #if _GLIBCXX_USE_DEPRECATED
  51 #pragma GCC diagnostic push
  52 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  53   template<typename> class auto_ptr;
  54 #pragma GCC diagnostic pop
  55 #endif
  56
  57   /// Primary template of default_delete, used by unique_ptr
  58   template<typename _Tp>
  59     struct default_delete
  60     {
  61       /// Default constructor
  62       constexpr default_delete() noexcept = default;
  63
  64       /** @brief Converting constructor.
  65        *
  66        * Allows conversion from a deleter for arrays of another type, @p _Up,
  67        * only if @p _Up* is convertible to @p _Tp*.
  68        */
  69       template<typename _Up, typename = typename
  70                enable_if<is_convertible<_Up*, _Tp*>::value>::type>
  71         default_delete(const default_delete<_Up>&) noexcept { }
  72
  73       /// Calls @c delete @p __ptr
  74       void
  75       operator()(_Tp* __ptr) const
  76       {
  77         static_assert(!is_void<_Tp>::value,
  78                       "can't delete pointer to incomplete type");
  79         static_assert(sizeof(_Tp)>0,
  80                       "can't delete pointer to incomplete type");
  81         delete __ptr;
  82       }
  83     };
  84
  85   // _GLIBCXX_RESOLVE_LIB_DEFECTS
  86   // DR 740 - omit specialization for array objects with a compile time length
  87   /// Specialization for arrays, default_delete.
  88   template<typename _Tp>
  89     struct default_delete<_Tp[]>
  90     {
  91     public:
  92       /// Default constructor
  93       constexpr default_delete() noexcept = default;
  94
  95       /** @brief Converting constructor.
  96        *
  97        * Allows conversion from a deleter for arrays of another type, such as
  98        * a const-qualified version of @p _Tp.
  99        *
 100        * Conversions from types derived from @c _Tp are not allowed because
 101        * it is unsafe to @c delete[] an array of derived types through a
 102        * pointer to the base type.
 103        */
 104       template<typename _Up, typename = typename
 105                enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type>
 106         default_delete(const default_delete<_Up[]>&) noexcept { }
 107
 108       /// Calls @c delete[] @p __ptr
 109       template<typename _Up>
 110       typename enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type
 111         operator()(_Up* __ptr) const
 112       {
 113         static_assert(sizeof(_Tp)>0,
 114                       "can't delete pointer to incomplete type");
 115         delete [] __ptr;
 116       }
 117     };
 118
 119   template <typename _Tp, typename _Dp>
 120     class __uniq_ptr_impl
 121     {
 122       template <typename _Up, typename _Ep, typename = void>
 123         struct _Ptr
 124         {
 125           using type = _Up*;
 126         };
 127
 128       template <typename _Up, typename _Ep>
 129         struct
 130         _Ptr<_Up, _Ep, __void_t<typename remove_reference<_Ep>::type::pointer>>
 131         {
 132           using type = typename remove_reference<_Ep>::type::pointer;
 133         };
 134
 135     public:
 136       using _DeleterConstraint = enable_if<
 137         __and_<__not_<is_pointer<_Dp>>,
 138                is_default_constructible<_Dp>>::value>;
 139
 140       using pointer = typename _Ptr<_Tp, _Dp>::type;
 141
 142       static_assert( !is_rvalue_reference<_Dp>::value,
 143                      "unique_ptr's deleter type must be a function object type"
 144                      " or an lvalue reference type" );
 145       static_assert( __is_invocable<_Dp&, pointer&>::value,
 146                      "unique_ptr's deleter must be invocable with a pointer" );
 147
 148       __uniq_ptr_impl() = default;
 149       __uniq_ptr_impl(pointer __p) : _M_t() { _M_ptr() = __p; }
 150
 151       template<typename _Del>
 152       __uniq_ptr_impl(pointer __p, _Del&& __d)
 153         : _M_t(__p, std::forward<_Del>(__d)) { }
 154
 155       pointer&   _M_ptr() { return std::get<0>(_M_t); }
 156       pointer    _M_ptr() const { return std::get<0>(_M_t); }
 157       _Dp&       _M_deleter() { return std::get<1>(_M_t); }
 158       const _Dp& _M_deleter() const { return std::get<1>(_M_t); }
 159
 160     private:
 161       tuple<pointer, _Dp> _M_t;
 162     };
 163
 164   /// 20.7.1.2 unique_ptr for single objects.
 165   template <typename _Tp, typename _Dp = default_delete<_Tp>>
 166     class unique_ptr
 167     {
 168       template <typename _Up>
 169         using _DeleterConstraint =
 170           typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;
 171
 172       __uniq_ptr_impl<_Tp, _Dp> _M_t;
 173
 174     public:
 175       using pointer       = typename __uniq_ptr_impl<_Tp, _Dp>::pointer;
 176       using element_type  = _Tp;
 177       using deleter_type  = _Dp;
 178
 179     private:
 180       // helper template for detecting a safe conversion from another
 181       // unique_ptr
 182       template<typename _Up, typename _Ep>
 183         using __safe_conversion_up = __and_<
 184                 is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>,
 185                 __not_<is_array<_Up>>,
 186                 __or_<__and_<is_reference<deleter_type>,
 187                              is_same<deleter_type, _Ep>>,
 188                       __and_<__not_<is_reference<deleter_type>>,
 189                              is_convertible<_Ep, deleter_type>>
 190                 >
 191               >;
 192
 193     public:
 194       // Constructors.
 195
 196       /// Default constructor, creates a unique_ptr that owns nothing.
 197       template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 198         constexpr unique_ptr() noexcept
 199         : _M_t()
 200         { }
 201
 202       /** Takes ownership of a pointer.
 203        *
 204        * @param __p  A pointer to an object of @c element_type
 205        *
 206        * The deleter will be value-initialized.
 207        */
 208       template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 209         explicit
 210         unique_ptr(pointer __p) noexcept
 211         : _M_t(__p)
 212         { }
 213
 214       /** Takes ownership of a pointer.
 215        *
 216        * @param __p  A pointer to an object of @c element_type
 217        * @param __d  A reference to a deleter.
 218        *
 219        * The deleter will be initialized with @p __d
 220        */
 221       template<typename _Del = deleter_type,
 222                typename = _Require<is_copy_constructible<_Del>>>
 223         unique_ptr(pointer __p, const deleter_type& __d) noexcept
 224         : _M_t(__p, __d) { }
 225
 226       /** Takes ownership of a pointer.
 227        *
 228        * @param __p  A pointer to an object of @c element_type
 229        * @param __d  An rvalue reference to a (non-reference) deleter.
 230        *
 231        * The deleter will be initialized with @p std::move(__d)
 232        */
 233       template<typename _Del = deleter_type,
 234                typename = _Require<is_move_constructible<_Del>>>
 235         unique_ptr(pointer __p,
 236                    __enable_if_t<!is_lvalue_reference<_Del>::value,
 237                                  _Del&&> __d) noexcept
 238         : _M_t(__p, std::move(__d))
 239         { }
 240
 241       template<typename _Del = deleter_type,
 242                typename _DelUnref = typename remove_reference<_Del>::type>
 243         unique_ptr(pointer,
 244                    __enable_if_t<is_lvalue_reference<_Del>::value,
 245                                  _DelUnref&&>) = delete;
 246
 247       /// Creates a unique_ptr that owns nothing.
 248       template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 249         constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
 250
 251       // Move constructors.
 252
 253       /// Move constructor.
 254       unique_ptr(unique_ptr&& __u) noexcept
 255       : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) { }
 256
 257       /** @brief Converting constructor from another type
 258        *
 259        * Requires that the pointer owned by @p __u is convertible to the
 260        * type of pointer owned by this object, @p __u does not own an array,
 261        * and @p __u has a compatible deleter type.
 262        */
 263       template<typename _Up, typename _Ep, typename = _Require<
 264                __safe_conversion_up<_Up, _Ep>,
 265                typename conditional<is_reference<_Dp>::value,
 266                                     is_same<_Ep, _Dp>,
 267                                     is_convertible<_Ep, _Dp>>::type>>
 268         unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
 269         : _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
 270         { }
 271
 272 #if _GLIBCXX_USE_DEPRECATED
 273 #pragma GCC diagnostic push
 274 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 275       /// Converting constructor from @c auto_ptr
 276       template<typename _Up, typename = _Require<
 277                is_convertible<_Up*, _Tp*>, is_same<_Dp, default_delete<_Tp>>>>
 278         unique_ptr(auto_ptr<_Up>&& __u) noexcept;
 279 #pragma GCC diagnostic pop
 280 #endif
 281
 282       /// Destructor, invokes the deleter if the stored pointer is not null.
 283       ~unique_ptr() noexcept
 284       {
 285         auto& __ptr = _M_t._M_ptr();
 286         if (__ptr != nullptr)
 287           get_deleter()(__ptr);
 288         __ptr = pointer();
 289       }
 290
 291       // Assignment.
 292
 293       /** @brief Move assignment operator.
 294        *
 295        * @param __u  The object to transfer ownership from.
 296        *
 297        * Invokes the deleter first if this object owns a pointer.
 298        */
 299       unique_ptr&
 300       operator=(unique_ptr&& __u) noexcept
 301       {
 302         reset(__u.release());
 303         get_deleter() = std::forward<deleter_type>(__u.get_deleter());
 304         return *this;
 305       }
 306
 307       /** @brief Assignment from another type.
 308        *
 309        * @param __u  The object to transfer ownership from, which owns a
 310        *             convertible pointer to a non-array object.
 311        *
 312        * Invokes the deleter first if this object owns a pointer.
 313        */
 314       template<typename _Up, typename _Ep>
 315         typename enable_if< __and_<
 316           __safe_conversion_up<_Up, _Ep>,
 317           is_assignable<deleter_type&, _Ep&&>
 318           >::value,
 319           unique_ptr&>::type
 320         operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
 321         {
 322           reset(__u.release());
 323           get_deleter() = std::forward<_Ep>(__u.get_deleter());
 324           return *this;
 325         }
 326
 327       /// Reset the %unique_ptr to empty, invoking the deleter if necessary.
 328       unique_ptr&
 329       operator=(nullptr_t) noexcept
 330       {
 331         reset();
 332         return *this;
 333       }
 334
 335       // Observers.
 336
 337       /// Dereference the stored pointer.
 338       typename add_lvalue_reference<element_type>::type
 339       operator*() const
 340       {
 341         __glibcxx_assert(get() != pointer());
 342         return *get();
 343       }
 344
 345       /// Return the stored pointer.
 346       pointer
 347       operator->() const noexcept
 348       {
 349         _GLIBCXX_DEBUG_PEDASSERT(get() != pointer());
 350         return get();
 351       }
 352
 353       /// Return the stored pointer.
 354       pointer
 355       get() const noexcept
 356       { return _M_t._M_ptr(); }
 357
 358       /// Return a reference to the stored deleter.
 359       deleter_type&
 360       get_deleter() noexcept
 361       { return _M_t._M_deleter(); }
 362
 363       /// Return a reference to the stored deleter.
 364       const deleter_type&
 365       get_deleter() const noexcept
 366       { return _M_t._M_deleter(); }
 367
 368       /// Return @c true if the stored pointer is not null.
 369       explicit operator bool() const noexcept
 370       { return get() == pointer() ? false : true; }
 371
 372       // Modifiers.
 373
 374       /// Release ownership of any stored pointer.
 375       pointer
 376       release() noexcept
 377       {
 378         pointer __p = get();
 379         _M_t._M_ptr() = pointer();
 380         return __p;
 381       }
 382
 383       /** @brief Replace the stored pointer.
 384        *
 385        * @param __p  The new pointer to store.
 386        *
 387        * The deleter will be invoked if a pointer is already owned.
 388        */
 389       void
 390       reset(pointer __p = pointer()) noexcept
 391       {
 392         using std::swap;
 393         swap(_M_t._M_ptr(), __p);
 394         if (__p != pointer())
 395           get_deleter()(__p);
 396       }
 397
 398       /// Exchange the pointer and deleter with another object.
 399       void
 400       swap(unique_ptr& __u) noexcept
 401       {
 402         using std::swap;
 403         swap(_M_t, __u._M_t);
 404       }
 405
 406       // Disable copy from lvalue.
 407       unique_ptr(const unique_ptr&) = delete;
 408       unique_ptr& operator=(const unique_ptr&) = delete;
 409   };
 410
 411   /// 20.7.1.3 unique_ptr for array objects with a runtime length
 412   // [unique.ptr.runtime]
 413   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 414   // DR 740 - omit specialization for array objects with a compile time length
 415   template<typename _Tp, typename _Dp>
 416     class unique_ptr<_Tp[], _Dp>
 417     {
 418       template <typename _Up>
 419       using _DeleterConstraint =
 420         typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;
 421
 422       __uniq_ptr_impl<_Tp, _Dp> _M_t;
 423
 424       template<typename _Up>
 425         using __remove_cv = typename remove_cv<_Up>::type;
 426
 427       // like is_base_of<_Tp, _Up> but false if unqualified types are the same
 428       template<typename _Up>
 429         using __is_derived_Tp
 430           = __and_< is_base_of<_Tp, _Up>,
 431                     __not_<is_same<__remove_cv<_Tp>, __remove_cv<_Up>>> >;
 432
 433     public:
 434       using pointer       = typename __uniq_ptr_impl<_Tp, _Dp>::pointer;
 435       using element_type  = _Tp;
 436       using deleter_type  = _Dp;
 437
 438       // helper template for detecting a safe conversion from another
 439       // unique_ptr
 440       template<typename _Up, typename _Ep,
 441                typename _Up_up = unique_ptr<_Up, _Ep>,
 442                typename _Up_element_type = typename _Up_up::element_type>
 443         using __safe_conversion_up = __and_<
 444           is_array<_Up>,
 445           is_same<pointer, element_type*>,
 446           is_same<typename _Up_up::pointer, _Up_element_type*>,
 447           is_convertible<_Up_element_type(*)[], element_type(*)[]>,
 448           __or_<__and_<is_reference<deleter_type>, is_same<deleter_type, _Ep>>,
 449                 __and_<__not_<is_reference<deleter_type>>,
 450                        is_convertible<_Ep, deleter_type>>>
 451         >;
 452
 453       // helper template for detecting a safe conversion from a raw pointer
 454       template<typename _Up>
 455         using __safe_conversion_raw = __and_<
 456           __or_<__or_<is_same<_Up, pointer>,
 457                       is_same<_Up, nullptr_t>>,
 458                 __and_<is_pointer<_Up>,
 459                        is_same<pointer, element_type*>,
 460                        is_convertible<
 461                          typename remove_pointer<_Up>::type(*)[],
 462                          element_type(*)[]>
 463                 >
 464           >
 465         >;
 466
 467       // Constructors.
 468
 469       /// Default constructor, creates a unique_ptr that owns nothing.
 470       template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 471         constexpr unique_ptr() noexcept
 472         : _M_t()
 473         { }
 474
 475       /** Takes ownership of a pointer.
 476        *
 477        * @param __p  A pointer to an array of a type safely convertible
 478        * to an array of @c element_type
 479        *
 480        * The deleter will be value-initialized.
 481        */
 482       template<typename _Up,
 483                typename _Vp = _Dp,
 484                typename = _DeleterConstraint<_Vp>,
 485                typename = typename enable_if<
 486                  __safe_conversion_raw<_Up>::value, bool>::type>
 487         explicit
 488         unique_ptr(_Up __p) noexcept
 489         : _M_t(__p)
 490         { }
 491
 492       /** Takes ownership of a pointer.
 493        *
 494        * @param __p  A pointer to an array of a type safely convertible
 495        * to an array of @c element_type
 496        * @param __d  A reference to a deleter.
 497        *
 498        * The deleter will be initialized with @p __d
 499        */
 500       template<typename _Up, typename _Del = deleter_type,
 501                typename = _Require<__safe_conversion_raw<_Up>,
 502                                    is_copy_constructible<_Del>>>
 503       unique_ptr(_Up __p, const deleter_type& __d) noexcept
 504       : _M_t(__p, __d) { }
 505
 506       /** Takes ownership of a pointer.
 507        *
 508        * @param __p  A pointer to an array of a type safely convertible
 509        * to an array of @c element_type
 510        * @param __d  A reference to a deleter.
 511        *
 512        * The deleter will be initialized with @p std::move(__d)
 513        */
 514       template<typename _Up, typename _Del = deleter_type,
 515                typename = _Require<__safe_conversion_raw<_Up>,
 516                                    is_move_constructible<_Del>>>
 517         unique_ptr(_Up __p,
 518                    __enable_if_t<!is_lvalue_reference<_Del>::value,
 519                                  _Del&&> __d) noexcept
 520         : _M_t(std::move(__p), std::move(__d))
 521         { }
 522
 523       template<typename _Up, typename _Del = deleter_type,
 524                typename _DelUnref = typename remove_reference<_Del>::type,
 525                typename = _Require<__safe_conversion_raw<_Up>>>
 526         unique_ptr(_Up,
 527                    __enable_if_t<is_lvalue_reference<_Del>::value,
 528                                  _DelUnref&&>) = delete;
 529
 530       /// Move constructor.
 531       unique_ptr(unique_ptr&& __u) noexcept
 532       : _M_t(__u.release(), std::forward<deleter_type>(__u.get_deleter())) { }
 533
 534       /// Creates a unique_ptr that owns nothing.
 535       template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
 536         constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
 537
 538       template<typename _Up, typename _Ep,
 539                typename = _Require<__safe_conversion_up<_Up, _Ep>>>
 540         unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
 541         : _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
 542         { }
 543
 544       /// Destructor, invokes the deleter if the stored pointer is not null.
 545       ~unique_ptr()
 546       {
 547         auto& __ptr = _M_t._M_ptr();
 548         if (__ptr != nullptr)
 549           get_deleter()(__ptr);
 550         __ptr = pointer();
 551       }
 552
 553       // Assignment.
 554
 555       /** @brief Move assignment operator.
 556        *
 557        * @param __u  The object to transfer ownership from.
 558        *
 559        * Invokes the deleter first if this object owns a pointer.
 560        */
 561       unique_ptr&
 562       operator=(unique_ptr&& __u) noexcept
 563       {
 564         reset(__u.release());
 565         get_deleter() = std::forward<deleter_type>(__u.get_deleter());
 566         return *this;
 567       }
 568
 569       /** @brief Assignment from another type.
 570        *
 571        * @param __u  The object to transfer ownership from, which owns a
 572        *             convertible pointer to an array object.
 573        *
 574        * Invokes the deleter first if this object owns a pointer.
 575        */
 576       template<typename _Up, typename _Ep>
 577         typename
 578         enable_if<__and_<__safe_conversion_up<_Up, _Ep>,
 579                          is_assignable<deleter_type&, _Ep&&>
 580                   >::value,
 581                   unique_ptr&>::type
 582         operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
 583         {
 584           reset(__u.release());
 585           get_deleter() = std::forward<_Ep>(__u.get_deleter());
 586           return *this;
 587         }
 588
 589       /// Reset the %unique_ptr to empty, invoking the deleter if necessary.
 590       unique_ptr&
 591       operator=(nullptr_t) noexcept
 592       {
 593         reset();
 594         return *this;
 595       }
 596
 597       // Observers.
 598
 599       /// Access an element of owned array.
 600       typename std::add_lvalue_reference<element_type>::type
 601       operator[](size_t __i) const
 602       {
 603         __glibcxx_assert(get() != pointer());
 604         return get()[__i];
 605       }
 606
 607       /// Return the stored pointer.
 608       pointer
 609       get() const noexcept
 610       { return _M_t._M_ptr(); }
 611
 612       /// Return a reference to the stored deleter.
 613       deleter_type&
 614       get_deleter() noexcept
 615       { return _M_t._M_deleter(); }
 616
 617       /// Return a reference to the stored deleter.
 618       const deleter_type&
 619       get_deleter() const noexcept
 620       { return _M_t._M_deleter(); }
 621
 622       /// Return @c true if the stored pointer is not null.
 623       explicit operator bool() const noexcept
 624       { return get() == pointer() ? false : true; }
 625
 626       // Modifiers.
 627
 628       /// Release ownership of any stored pointer.
 629       pointer
 630       release() noexcept
 631       {
 632         pointer __p = get();
 633         _M_t._M_ptr() = pointer();
 634         return __p;
 635       }
 636
 637       /** @brief Replace the stored pointer.
 638        *
 639        * @param __p  The new pointer to store.
 640        *
 641        * The deleter will be invoked if a pointer is already owned.
 642        */
 643       template <typename _Up,
 644                 typename = _Require<
 645                   __or_<is_same<_Up, pointer>,
 646                         __and_<is_same<pointer, element_type*>,
 647                                is_pointer<_Up>,
 648                                is_convertible<
 649                                  typename remove_pointer<_Up>::type(*)[],
 650                                  element_type(*)[]
 651                                >
 652                         >
 653                   >
 654                >>
 655       void
 656       reset(_Up __p) noexcept
 657       {
 658         pointer __ptr = __p;
 659         using std::swap;
 660         swap(_M_t._M_ptr(), __ptr);
 661         if (__ptr != nullptr)
 662           get_deleter()(__ptr);
 663       }
 664
 665       void reset(nullptr_t = nullptr) noexcept
 666       {
 667         reset(pointer());
 668       }
 669
 670       /// Exchange the pointer and deleter with another object.
 671       void
 672       swap(unique_ptr& __u) noexcept
 673       {
 674         using std::swap;
 675         swap(_M_t, __u._M_t);
 676       }
 677
 678       // Disable copy from lvalue.
 679       unique_ptr(const unique_ptr&) = delete;
 680       unique_ptr& operator=(const unique_ptr&) = delete;
 681     };
 682
 683   template<typename _Tp, typename _Dp>
 684     inline
 685 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
 686     // Constrained free swap overload, see p0185r1
 687     typename enable_if<__is_swappable<_Dp>::value>::type
 688 #else
 689     void
 690 #endif
 691     swap(unique_ptr<_Tp, _Dp>& __x,
 692          unique_ptr<_Tp, _Dp>& __y) noexcept
 693     { __x.swap(__y); }
 694
 695 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
 696   template<typename _Tp, typename _Dp>
 697     typename enable_if<!__is_swappable<_Dp>::value>::type
 698     swap(unique_ptr<_Tp, _Dp>&,
 699          unique_ptr<_Tp, _Dp>&) = delete;
 700 #endif
 701
 702   template<typename _Tp, typename _Dp,
 703            typename _Up, typename _Ep>
 704     inline bool
 705     operator==(const unique_ptr<_Tp, _Dp>& __x,
 706                const unique_ptr<_Up, _Ep>& __y)
 707     { return __x.get() == __y.get(); }
 708
 709   template<typename _Tp, typename _Dp>
 710     inline bool
 711     operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
 712     { return !__x; }
 713
 714   template<typename _Tp, typename _Dp>
 715     inline bool
 716     operator==(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
 717     { return !__x; }
 718
 719   template<typename _Tp, typename _Dp,
 720            typename _Up, typename _Ep>
 721     inline bool
 722     operator!=(const unique_ptr<_Tp, _Dp>& __x,
 723                const unique_ptr<_Up, _Ep>& __y)
 724     { return __x.get() != __y.get(); }
 725
 726   template<typename _Tp, typename _Dp>
 727     inline bool
 728     operator!=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
 729     { return (bool)__x; }
 730
 731   template<typename _Tp, typename _Dp>
 732     inline bool
 733     operator!=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
 734     { return (bool)__x; }
 735
 736   template<typename _Tp, typename _Dp,
 737            typename _Up, typename _Ep>
 738     inline bool
 739     operator<(const unique_ptr<_Tp, _Dp>& __x,
 740               const unique_ptr<_Up, _Ep>& __y)
 741     {
 742       typedef typename
 743         std::common_type<typename unique_ptr<_Tp, _Dp>::pointer,
 744                          typename unique_ptr<_Up, _Ep>::pointer>::type _CT;
 745       return std::less<_CT>()(__x.get(), __y.get());
 746     }
 747
 748   template<typename _Tp, typename _Dp>
 749     inline bool
 750     operator<(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
 751     { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
 752                                                                  nullptr); }
 753
 754   template<typename _Tp, typename _Dp>
 755     inline bool
 756     operator<(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
 757     { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
 758                                                                  __x.get()); }
 759
 760   template<typename _Tp, typename _Dp,
 761            typename _Up, typename _Ep>
 762     inline bool
 763     operator<=(const unique_ptr<_Tp, _Dp>& __x,
 764                const unique_ptr<_Up, _Ep>& __y)
 765     { return !(__y < __x); }
 766
 767   template<typename _Tp, typename _Dp>
 768     inline bool
 769     operator<=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
 770     { return !(nullptr < __x); }
 771
 772   template<typename _Tp, typename _Dp>
 773     inline bool
 774     operator<=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
 775     { return !(__x < nullptr); }
 776
 777   template<typename _Tp, typename _Dp,
 778            typename _Up, typename _Ep>
 779     inline bool
 780     operator>(const unique_ptr<_Tp, _Dp>& __x,
 781               const unique_ptr<_Up, _Ep>& __y)
 782     { return (__y < __x); }
 783
 784   template<typename _Tp, typename _Dp>
 785     inline bool
 786     operator>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
 787     { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
 788                                                                  __x.get()); }
 789
 790   template<typename _Tp, typename _Dp>
 791     inline bool
 792     operator>(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
 793     { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
 794                                                                  nullptr); }
 795
 796   template<typename _Tp, typename _Dp,
 797            typename _Up, typename _Ep>
 798     inline bool
 799     operator>=(const unique_ptr<_Tp, _Dp>& __x,
 800                const unique_ptr<_Up, _Ep>& __y)
 801     { return !(__x < __y); }
 802
 803   template<typename _Tp, typename _Dp>
 804     inline bool
 805     operator>=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
 806     { return !(__x < nullptr); }
 807
 808   template<typename _Tp, typename _Dp>
 809     inline bool
 810     operator>=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
 811     { return !(nullptr < __x); }
 812
 813   /// std::hash specialization for unique_ptr.
 814   template<typename _Tp, typename _Dp>
 815     struct hash<unique_ptr<_Tp, _Dp>>
 816     : public __hash_base<size_t, unique_ptr<_Tp, _Dp>>,
 817     private __poison_hash<typename unique_ptr<_Tp, _Dp>::pointer>
 818     {
 819       size_t
 820       operator()(const unique_ptr<_Tp, _Dp>& __u) const noexcept
 821       {
 822         typedef unique_ptr<_Tp, _Dp> _UP;
 823         return std::hash<typename _UP::pointer>()(__u.get());
 824       }
 825     };
 826
 827 #if __cplusplus > 201103L
 828
 829 #define __cpp_lib_make_unique 201304
 830
 831   template<typename _Tp>
 832     struct _MakeUniq
 833     { typedef unique_ptr<_Tp> __single_object; };
 834
 835   template<typename _Tp>
 836     struct _MakeUniq<_Tp[]>
 837     { typedef unique_ptr<_Tp[]> __array; };
 838
 839   template<typename _Tp, size_t _Bound>
 840     struct _MakeUniq<_Tp[_Bound]>
 841     { struct __invalid_type { }; };
 842
 843   /// std::make_unique for single objects
 844   template<typename _Tp, typename... _Args>
 845     inline typename _MakeUniq<_Tp>::__single_object
 846     make_unique(_Args&&... __args)
 847     { return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }
 848
 849   /// std::make_unique for arrays of unknown bound
 850   template<typename _Tp>
 851     inline typename _MakeUniq<_Tp>::__array
 852     make_unique(size_t __num)
 853     { return unique_ptr<_Tp>(new remove_extent_t<_Tp>[__num]()); }
 854
 855   /// Disable std::make_unique for arrays of known bound
 856   template<typename _Tp, typename... _Args>
 857     inline typename _MakeUniq<_Tp>::__invalid_type
 858     make_unique(_Args&&...) = delete;
 859 #endif
 860
 861   // @} group pointer_abstractions
 862
 863 _GLIBCXX_END_NAMESPACE_VERSION
 864 } // namespace
 865
 866 #endif /* _UNIQUE_PTR_H */