gnu/dist/gcc4/libstdc++-v3/include/debug/safe_iterator.h

   1 // Safe iterator implementation  -*- C++ -*-
   2
   3 // Copyright (C) 2003, 2004, 2005
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 2, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 #ifndef _GLIBCXX_DEBUG_SAFE_ITERATOR_H
  32 #define _GLIBCXX_DEBUG_SAFE_ITERATOR_H 1
  33
  34 #include <debug/debug.h>
  35 #include <debug/macros.h>
  36 #include <debug/functions.h>
  37 #include <debug/formatter.h>
  38 #include <debug/safe_base.h>
  39 #include <bits/stl_pair.h>
  40 #include <bits/cpp_type_traits.h>
  41
  42 namespace __gnu_debug
  43 {
  44   using std::iterator_traits;
  45   using std::pair;
  46
  47   /** Iterators that derive from _Safe_iterator_base but that aren't
  48    *  _Safe_iterators can be determined singular or non-singular via
  49    *  _Safe_iterator_base.
  50    */
  51   inline bool
  52   __check_singular_aux(const _Safe_iterator_base* __x)
  53   { return __x->_M_singular(); }
  54
  55   /** \brief Safe iterator wrapper.
  56    *
  57    *  The class template %_Safe_iterator is a wrapper around an
  58    *  iterator that tracks the iterator's movement among sequences and
  59    *  checks that operations performed on the "safe" iterator are
  60    *  legal. In additional to the basic iterator operations (which are
  61    *  validated, and then passed to the underlying iterator),
  62    *  %_Safe_iterator has member functions for iterator invalidation,
  63    *  attaching/detaching the iterator from sequences, and querying
  64    *  the iterator's state.
  65    */
  66   template<typename _Iterator, typename _Sequence>
  67     class _Safe_iterator : public _Safe_iterator_base
  68     {
  69       typedef _Safe_iterator _Self;
  70
  71       /** The precision to which we can calculate the distance between
  72        *  two iterators.
  73        */
  74       enum _Distance_precision
  75         {
  76           __dp_equality, //< Can compare iterator equality, only
  77           __dp_sign,     //< Can determine equality and ordering
  78           __dp_exact     //< Can determine distance precisely
  79         };
  80
  81       /// The underlying iterator
  82       _Iterator _M_current;
  83
  84       /// Determine if this is a constant iterator.
  85       bool
  86       _M_constant() const
  87       {
  88         typedef typename _Sequence::const_iterator const_iterator;
  89         return __is_same<const_iterator, _Safe_iterator>::value;
  90       }
  91
  92       typedef iterator_traits<_Iterator> _Traits;
  93
  94     public:
  95       typedef _Iterator                           _Base_iterator;
  96       typedef typename _Traits::iterator_category iterator_category;
  97       typedef typename _Traits::value_type        value_type;
  98       typedef typename _Traits::difference_type   difference_type;
  99       typedef typename _Traits::reference         reference;
 100       typedef typename _Traits::pointer           pointer;
 101
 102       /// @post the iterator is singular and unattached
 103       _Safe_iterator() : _M_current() { }
 104
 105       /**
 106        * @brief Safe iterator construction from an unsafe iterator and
 107        * its sequence.
 108        *
 109        * @pre @p seq is not NULL
 110        * @post this is not singular
 111        */
 112       _Safe_iterator(const _Iterator& __i, const _Sequence* __seq)
 113       : _Safe_iterator_base(__seq, _M_constant()), _M_current(__i)
 114       {
 115         _GLIBCXX_DEBUG_VERIFY(! this->_M_singular(),
 116                               _M_message(__msg_init_singular)
 117                               ._M_iterator(*this, "this"));
 118       }
 119
 120       /**
 121        * @brief Copy construction.
 122        * @pre @p x is not singular
 123        */
 124       _Safe_iterator(const _Safe_iterator& __x)
 125       : _Safe_iterator_base(__x, _M_constant()), _M_current(__x._M_current)
 126       {
 127         _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 128                               _M_message(__msg_init_copy_singular)
 129                               ._M_iterator(*this, "this")
 130                               ._M_iterator(__x, "other"));
 131       }
 132
 133       /**
 134        *  @brief Converting constructor from a mutable iterator to a
 135        *  constant iterator.
 136        *
 137        *  @pre @p x is not singular
 138       */
 139       template<typename _MutableIterator>
 140         _Safe_iterator(
 141           const _Safe_iterator<_MutableIterator,
 142           typename std::__enable_if<
 143                      _Sequence,
 144                      (std::__are_same<_MutableIterator,
 145                       typename _Sequence::iterator::_Base_iterator>::__value)
 146                    >::__type>& __x)
 147         : _Safe_iterator_base(__x, _M_constant()), _M_current(__x.base())
 148         {
 149           _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 150                                 _M_message(__msg_init_const_singular)
 151                                 ._M_iterator(*this, "this")
 152                                 ._M_iterator(__x, "other"));
 153         }
 154
 155       /**
 156        * @brief Copy assignment.
 157        * @pre @p x is not singular
 158        */
 159       _Safe_iterator&
 160       operator=(const _Safe_iterator& __x)
 161       {
 162         _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 163                               _M_message(__msg_copy_singular)
 164                               ._M_iterator(*this, "this")
 165                               ._M_iterator(__x, "other"));
 166         _M_current = __x._M_current;
 167         this->_M_attach(static_cast<_Sequence*>(__x._M_sequence));
 168         return *this;
 169       }
 170
 171       /**
 172        *  @brief Iterator dereference.
 173        *  @pre iterator is dereferenceable
 174        */
 175       reference
 176       operator*() const
 177       {
 178
 179         _GLIBCXX_DEBUG_VERIFY(this->_M_dereferenceable(),
 180                               _M_message(__msg_bad_deref)
 181                               ._M_iterator(*this, "this"));
 182         return *_M_current;
 183       }
 184
 185       /**
 186        *  @brief Iterator dereference.
 187        *  @pre iterator is dereferenceable
 188        *  @todo Make this correct w.r.t. iterators that return proxies
 189        *  @todo Use addressof() instead of & operator
 190        */
 191       pointer
 192       operator->() const
 193       {
 194         _GLIBCXX_DEBUG_VERIFY(this->_M_dereferenceable(),
 195                               _M_message(__msg_bad_deref)
 196                               ._M_iterator(*this, "this"));
 197         return &*_M_current;
 198       }
 199
 200       // ------ Input iterator requirements ------
 201       /**
 202        *  @brief Iterator preincrement
 203        *  @pre iterator is incrementable
 204        */
 205       _Safe_iterator&
 206       operator++()
 207       {
 208         _GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 209                               _M_message(__msg_bad_inc)
 210                               ._M_iterator(*this, "this"));
 211         ++_M_current;
 212         return *this;
 213       }
 214
 215       /**
 216        *  @brief Iterator postincrement
 217        *  @pre iterator is incrementable
 218        */
 219       _Safe_iterator
 220       operator++(int)
 221       {
 222         _GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 223                               _M_message(__msg_bad_inc)
 224                               ._M_iterator(*this, "this"));
 225         _Safe_iterator __tmp(*this);
 226         ++_M_current;
 227         return __tmp;
 228       }
 229
 230       // ------ Bidirectional iterator requirements ------
 231       /**
 232        *  @brief Iterator predecrement
 233        *  @pre iterator is decrementable
 234        */
 235       _Safe_iterator&
 236       operator--()
 237       {
 238         _GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 239                               _M_message(__msg_bad_dec)
 240                               ._M_iterator(*this, "this"));
 241         --_M_current;
 242         return *this;
 243       }
 244
 245       /**
 246        *  @brief Iterator postdecrement
 247        *  @pre iterator is decrementable
 248        */
 249       _Safe_iterator
 250       operator--(int)
 251       {
 252         _GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 253                               _M_message(__msg_bad_dec)
 254                               ._M_iterator(*this, "this"));
 255         _Safe_iterator __tmp(*this);
 256         --_M_current;
 257         return __tmp;
 258       }
 259
 260       // ------ Random access iterator requirements ------
 261       reference
 262       operator[](const difference_type& __n) const
 263       {
 264         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(__n)
 265                               && this->_M_can_advance(__n+1),
 266                               _M_message(__msg_iter_subscript_oob)
 267                               ._M_iterator(*this)._M_integer(__n));
 268
 269         return _M_current[__n];
 270       }
 271
 272       _Safe_iterator&
 273       operator+=(const difference_type& __n)
 274       {
 275         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(__n),
 276                               _M_message(__msg_advance_oob)
 277                               ._M_iterator(*this)._M_integer(__n));
 278         _M_current += __n;
 279         return *this;
 280       }
 281
 282       _Safe_iterator
 283       operator+(const difference_type& __n) const
 284       {
 285         _Safe_iterator __tmp(*this);
 286         __tmp += __n;
 287         return __tmp;
 288       }
 289
 290       _Safe_iterator&
 291       operator-=(const difference_type& __n)
 292       {
 293         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(-__n),
 294                               _M_message(__msg_retreat_oob)
 295                               ._M_iterator(*this)._M_integer(__n));
 296         _M_current += -__n;
 297         return *this;
 298       }
 299
 300       _Safe_iterator
 301       operator-(const difference_type& __n) const
 302       {
 303         _Safe_iterator __tmp(*this);
 304         __tmp -= __n;
 305         return __tmp;
 306       }
 307
 308       // ------ Utilities ------
 309       /**
 310        * @brief Return the underlying iterator
 311        */
 312       _Iterator
 313       base() const { return _M_current; }
 314
 315       /**
 316        * @brief Conversion to underlying non-debug iterator to allow
 317        * better interaction with non-debug containers.
 318        */
 319       operator _Iterator() const { return _M_current; }
 320
 321       /** Attach iterator to the given sequence. */
 322       void
 323       _M_attach(const _Sequence* __seq)
 324       {
 325         _Safe_iterator_base::_M_attach(const_cast<_Sequence*>(__seq),
 326                                        _M_constant());
 327       }
 328
 329       /** Invalidate the iterator, making it singular. */
 330       void
 331       _M_invalidate();
 332
 333       /// Is the iterator dereferenceable?
 334       bool
 335       _M_dereferenceable() const
 336       { return !this->_M_singular() && !_M_is_end(); }
 337
 338       /// Is the iterator incrementable?
 339       bool
 340       _M_incrementable() const { return this->_M_dereferenceable(); }
 341
 342       // Is the iterator decrementable?
 343       bool
 344       _M_decrementable() const { return !_M_singular() && !_M_is_begin(); }
 345
 346       // Can we advance the iterator @p __n steps (@p __n may be negative)
 347       bool
 348       _M_can_advance(const difference_type& __n) const;
 349
 350       // Is the iterator range [*this, __rhs) valid?
 351       template<typename _Other>
 352         bool
 353         _M_valid_range(const _Safe_iterator<_Other, _Sequence>& __rhs) const;
 354
 355       // The sequence this iterator references.
 356       const _Sequence*
 357       _M_get_sequence() const
 358       { return static_cast<const _Sequence*>(_M_sequence); }
 359
 360     /** Determine the distance between two iterators with some known
 361      *  precision.
 362     */
 363     template<typename _Iterator1, typename _Iterator2>
 364       static pair<difference_type, _Distance_precision>
 365       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs)
 366       {
 367         typedef typename iterator_traits<_Iterator1>::iterator_category
 368           _Category;
 369         return _M_get_distance(__lhs, __rhs, _Category());
 370       }
 371
 372     template<typename _Iterator1, typename _Iterator2>
 373       static pair<difference_type, _Distance_precision>
 374       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs,
 375                       std::random_access_iterator_tag)
 376       {
 377         return std::make_pair(__rhs.base() - __lhs.base(), __dp_exact);
 378       }
 379
 380     template<typename _Iterator1, typename _Iterator2>
 381       static pair<difference_type, _Distance_precision>
 382       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs,
 383                     std::forward_iterator_tag)
 384       {
 385         return std::make_pair(__lhs.base() == __rhs.base()? 0 : 1,
 386                               __dp_equality);
 387       }
 388
 389       /// Is this iterator equal to the sequence's begin() iterator?
 390       bool _M_is_begin() const
 391       { return *this == static_cast<const _Sequence*>(_M_sequence)->begin(); }
 392
 393       /// Is this iterator equal to the sequence's end() iterator?
 394       bool _M_is_end() const
 395       { return *this == static_cast<const _Sequence*>(_M_sequence)->end(); }
 396     };
 397
 398   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 399     inline bool
 400     operator==(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 401                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 402     {
 403       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 404                             _M_message(__msg_iter_compare_bad)
 405                             ._M_iterator(__lhs, "lhs")
 406                             ._M_iterator(__rhs, "rhs"));
 407       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 408                             _M_message(__msg_compare_different)
 409                             ._M_iterator(__lhs, "lhs")
 410                             ._M_iterator(__rhs, "rhs"));
 411       return __lhs.base() == __rhs.base();
 412     }
 413
 414   template<typename _Iterator, typename _Sequence>
 415     inline bool
 416     operator==(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 417                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 418     {
 419       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 420                             _M_message(__msg_iter_compare_bad)
 421                             ._M_iterator(__lhs, "lhs")
 422                             ._M_iterator(__rhs, "rhs"));
 423       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 424                             _M_message(__msg_compare_different)
 425                             ._M_iterator(__lhs, "lhs")
 426                             ._M_iterator(__rhs, "rhs"));
 427       return __lhs.base() == __rhs.base();
 428     }
 429
 430   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 431     inline bool
 432     operator!=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 433                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 434     {
 435       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 436                             _M_message(__msg_iter_compare_bad)
 437                             ._M_iterator(__lhs, "lhs")
 438                             ._M_iterator(__rhs, "rhs"));
 439       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 440                             _M_message(__msg_compare_different)
 441                             ._M_iterator(__lhs, "lhs")
 442                             ._M_iterator(__rhs, "rhs"));
 443       return __lhs.base() != __rhs.base();
 444     }
 445
 446   template<typename _Iterator, typename _Sequence>
 447     inline bool
 448     operator!=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 449                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 450     {
 451       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 452                             _M_message(__msg_iter_compare_bad)
 453                             ._M_iterator(__lhs, "lhs")
 454                             ._M_iterator(__rhs, "rhs"));
 455       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 456                             _M_message(__msg_compare_different)
 457                             ._M_iterator(__lhs, "lhs")
 458                             ._M_iterator(__rhs, "rhs"));
 459       return __lhs.base() != __rhs.base();
 460     }
 461
 462   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 463     inline bool
 464     operator<(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 465               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 466     {
 467       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 468                             _M_message(__msg_iter_order_bad)
 469                             ._M_iterator(__lhs, "lhs")
 470                             ._M_iterator(__rhs, "rhs"));
 471       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 472                             _M_message(__msg_order_different)
 473                             ._M_iterator(__lhs, "lhs")
 474                             ._M_iterator(__rhs, "rhs"));
 475       return __lhs.base() < __rhs.base();
 476     }
 477
 478   template<typename _Iterator, typename _Sequence>
 479     inline bool
 480     operator<(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 481               const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 482     {
 483       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 484                             _M_message(__msg_iter_order_bad)
 485                             ._M_iterator(__lhs, "lhs")
 486                             ._M_iterator(__rhs, "rhs"));
 487       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 488                             _M_message(__msg_order_different)
 489                             ._M_iterator(__lhs, "lhs")
 490                             ._M_iterator(__rhs, "rhs"));
 491       return __lhs.base() < __rhs.base();
 492     }
 493
 494   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 495     inline bool
 496     operator<=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 497                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 498     {
 499       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 500                             _M_message(__msg_iter_order_bad)
 501                             ._M_iterator(__lhs, "lhs")
 502                             ._M_iterator(__rhs, "rhs"));
 503       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 504                             _M_message(__msg_order_different)
 505                             ._M_iterator(__lhs, "lhs")
 506                             ._M_iterator(__rhs, "rhs"));
 507       return __lhs.base() <= __rhs.base();
 508     }
 509
 510   template<typename _Iterator, typename _Sequence>
 511     inline bool
 512     operator<=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 513                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 514     {
 515       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 516                             _M_message(__msg_iter_order_bad)
 517                             ._M_iterator(__lhs, "lhs")
 518                             ._M_iterator(__rhs, "rhs"));
 519       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 520                             _M_message(__msg_order_different)
 521                             ._M_iterator(__lhs, "lhs")
 522                             ._M_iterator(__rhs, "rhs"));
 523       return __lhs.base() <= __rhs.base();
 524     }
 525
 526   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 527     inline bool
 528     operator>(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 529               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 530     {
 531       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 532                             _M_message(__msg_iter_order_bad)
 533                             ._M_iterator(__lhs, "lhs")
 534                             ._M_iterator(__rhs, "rhs"));
 535       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 536                             _M_message(__msg_order_different)
 537                             ._M_iterator(__lhs, "lhs")
 538                             ._M_iterator(__rhs, "rhs"));
 539       return __lhs.base() > __rhs.base();
 540     }
 541
 542   template<typename _Iterator, typename _Sequence>
 543     inline bool
 544     operator>(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 545               const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 546     {
 547       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 548                             _M_message(__msg_iter_order_bad)
 549                             ._M_iterator(__lhs, "lhs")
 550                             ._M_iterator(__rhs, "rhs"));
 551       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 552                             _M_message(__msg_order_different)
 553                             ._M_iterator(__lhs, "lhs")
 554                             ._M_iterator(__rhs, "rhs"));
 555       return __lhs.base() > __rhs.base();
 556     }
 557
 558   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 559     inline bool
 560     operator>=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 561                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 562     {
 563       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 564                             _M_message(__msg_iter_order_bad)
 565                             ._M_iterator(__lhs, "lhs")
 566                             ._M_iterator(__rhs, "rhs"));
 567       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 568                             _M_message(__msg_order_different)
 569                             ._M_iterator(__lhs, "lhs")
 570                             ._M_iterator(__rhs, "rhs"));
 571       return __lhs.base() >= __rhs.base();
 572     }
 573
 574   template<typename _Iterator, typename _Sequence>
 575     inline bool
 576     operator>=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 577                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 578     {
 579       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 580                             _M_message(__msg_iter_order_bad)
 581                             ._M_iterator(__lhs, "lhs")
 582                             ._M_iterator(__rhs, "rhs"));
 583       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 584                             _M_message(__msg_order_different)
 585                             ._M_iterator(__lhs, "lhs")
 586                             ._M_iterator(__rhs, "rhs"));
 587       return __lhs.base() >= __rhs.base();
 588     }
 589
 590   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 591   // According to the resolution of DR179 not only the various comparison
 592   // operators but also operator- must accept mixed iterator/const_iterator
 593   // parameters.
 594   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 595     inline typename _Safe_iterator<_IteratorL, _Sequence>::difference_type
 596     operator-(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 597               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 598     {
 599       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 600                             _M_message(__msg_distance_bad)
 601                             ._M_iterator(__lhs, "lhs")
 602                             ._M_iterator(__rhs, "rhs"));
 603       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 604                             _M_message(__msg_distance_different)
 605                             ._M_iterator(__lhs, "lhs")
 606                             ._M_iterator(__rhs, "rhs"));
 607       return __lhs.base() - __rhs.base();
 608     }
 609
 610   template<typename _Iterator, typename _Sequence>
 611     inline _Safe_iterator<_Iterator, _Sequence>
 612     operator+(typename _Safe_iterator<_Iterator,_Sequence>::difference_type __n,
 613               const _Safe_iterator<_Iterator, _Sequence>& __i)
 614     { return __i + __n; }
 615 } // namespace __gnu_debug
 616
 617 #ifndef _GLIBCXX_EXPORT_TEMPLATE
 618 #  include <debug/safe_iterator.tcc>
 619 #endif
 620
 621 #endif