contrib/gcc-3.4/libstdc++-v3/include/debug/safe_iterator.h

   1 // Safe iterator implementation  -*- C++ -*-
   2
   3 // Copyright (C) 2003, 2004
   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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  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 <bits/stl_pair.h>
  35 #include <debug/debug.h>
  36 #include <debug/formatter.h>
  37 #include <debug/safe_base.h>
  38 #include <bits/cpp_type_traits.h>
  39
  40 namespace __gnu_debug
  41 {
  42   using std::iterator_traits;
  43   using std::pair;
  44
  45   /** Iterators that derive from _Safe_iterator_base but that aren't
  46    *  _Safe_iterators can be determined singular or non-singular via
  47    *  _Safe_iterator_base.
  48    */
  49   inline bool __check_singular_aux(const _Safe_iterator_base* __x)
  50   { return __x->_M_singular(); }
  51
  52   /** \brief Safe iterator wrapper.
  53    *
  54    *  The class template %_Safe_iterator is a wrapper around an
  55    *  iterator that tracks the iterator's movement among sequences and
  56    *  checks that operations performed on the "safe" iterator are
  57    *  legal. In additional to the basic iterator operations (which are
  58    *  validated, and then passed to the underlying iterator),
  59    *  %_Safe_iterator has member functions for iterator invalidation,
  60    *  attaching/detaching the iterator from sequences, and querying
  61    *  the iterator's state.
  62    */
  63   template<typename _Iterator, typename _Sequence>
  64     class _Safe_iterator : public _Safe_iterator_base
  65     {
  66       typedef _Safe_iterator _Self;
  67
  68       /** The precision to which we can calculate the distance between
  69        *  two iterators.
  70        */
  71       enum _Distance_precision
  72         {
  73           __dp_equality, //< Can compare iterator equality, only
  74           __dp_sign,     //< Can determine equality and ordering
  75           __dp_exact     //< Can determine distance precisely
  76         };
  77
  78       /// The underlying iterator
  79       _Iterator _M_current;
  80
  81       /// Determine if this is a constant iterator.
  82       bool
  83       _M_constant() const
  84       {
  85         typedef typename _Sequence::const_iterator const_iterator;
  86         return __is_same<const_iterator, _Safe_iterator>::value;
  87       }
  88
  89       typedef iterator_traits<_Iterator> _Traits;
  90
  91     public:
  92       typedef _Iterator                           _Base_iterator;
  93       typedef typename _Traits::iterator_category iterator_category;
  94       typedef typename _Traits::value_type        value_type;
  95       typedef typename _Traits::difference_type   difference_type;
  96       typedef typename _Traits::reference         reference;
  97       typedef typename _Traits::pointer           pointer;
  98
  99       /// @post the iterator is singular and unattached
 100       _Safe_iterator() : _M_current() { }
 101
 102       /**
 103        * @brief Safe iterator construction from an unsafe iterator and
 104        * its sequence.
 105        *
 106        * @pre @p seq is not NULL
 107        * @post this is not singular
 108        */
 109       _Safe_iterator(const _Iterator& __i, const _Sequence* __seq)
 110       : _Safe_iterator_base(__seq, _M_constant()), _M_current(__i)
 111       {
 112         _GLIBCXX_DEBUG_VERIFY(! this->_M_singular(),
 113                               _M_message(__msg_init_singular)
 114                               ._M_iterator(*this, "this"));
 115       }
 116
 117       /**
 118        * @brief Copy construction.
 119        * @pre @p x is not singular
 120        */
 121       _Safe_iterator(const _Safe_iterator& __x)
 122       : _Safe_iterator_base(__x, _M_constant()), _M_current(__x._M_current)
 123       {
 124         _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 125                               _M_message(__msg_init_copy_singular)
 126                               ._M_iterator(*this, "this")
 127                               ._M_iterator(__x, "other"));
 128       }
 129
 130       /**
 131        *  @brief Converting constructor from a mutable iterator to a
 132        *  constant iterator.
 133        *
 134        *  @pre @p x is not singular
 135       */
 136       template<typename _MutableIterator>
 137         _Safe_iterator(
 138           const _Safe_iterator<_MutableIterator,
 139           typename std::__enable_if<
 140                      _Sequence,
 141                      (std::__are_same<_MutableIterator,
 142                       typename _Sequence::iterator::_Base_iterator>::_M_type)
 143                    >::_M_type>& __x)
 144         : _Safe_iterator_base(__x, _M_constant()), _M_current(__x.base())
 145         {
 146           _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 147                                 _M_message(__msg_init_const_singular)
 148                                 ._M_iterator(*this, "this")
 149                                 ._M_iterator(__x, "other"));
 150         }
 151
 152       /**
 153        * @brief Copy assignment.
 154        * @pre @p x is not singular
 155        */
 156       _Safe_iterator&
 157       operator=(const _Safe_iterator& __x)
 158       {
 159         _GLIBCXX_DEBUG_VERIFY(!__x._M_singular(),
 160                               _M_message(__msg_copy_singular)
 161                               ._M_iterator(*this, "this")
 162                               ._M_iterator(__x, "other"));
 163         _M_current = __x._M_current;
 164         this->_M_attach(static_cast<_Sequence*>(__x._M_sequence));
 165         return *this;
 166       }
 167
 168       /**
 169        *  @brief Iterator dereference.
 170        *  @pre iterator is dereferenceable
 171        */
 172       reference
 173       operator*() const
 174       {
 175
 176         _GLIBCXX_DEBUG_VERIFY(this->_M_dereferenceable(),
 177                               _M_message(__msg_bad_deref)
 178                               ._M_iterator(*this, "this"));
 179         return *_M_current;
 180       }
 181
 182       /**
 183        *  @brief Iterator dereference.
 184        *  @pre iterator is dereferenceable
 185        *  @todo Make this correct w.r.t. iterators that return proxies
 186        *  @todo Use addressof() instead of & operator
 187        */
 188       pointer
 189       operator->() const
 190       {
 191         _GLIBCXX_DEBUG_VERIFY(this->_M_dereferenceable(),
 192                               _M_message(__msg_bad_deref)
 193                               ._M_iterator(*this, "this"));
 194         return &*_M_current;
 195       }
 196
 197       // ------ Input iterator requirements ------
 198       /**
 199        *  @brief Iterator preincrement
 200        *  @pre iterator is incrementable
 201        */
 202       _Safe_iterator&
 203       operator++()
 204       {
 205         _GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 206                               _M_message(__msg_bad_inc)
 207                               ._M_iterator(*this, "this"));
 208         ++_M_current;
 209         return *this;
 210       }
 211
 212       /**
 213        *  @brief Iterator postincrement
 214        *  @pre iterator is incrementable
 215        */
 216       _Safe_iterator
 217       operator++(int)
 218       {
 219         _GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
 220                               _M_message(__msg_bad_inc)
 221                               ._M_iterator(*this, "this"));
 222         _Safe_iterator __tmp(*this);
 223         ++_M_current;
 224         return __tmp;
 225       }
 226
 227       // ------ Bidirectional iterator requirements ------
 228       /**
 229        *  @brief Iterator predecrement
 230        *  @pre iterator is decrementable
 231        */
 232       _Safe_iterator&
 233       operator--()
 234       {
 235         _GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 236                               _M_message(__msg_bad_dec)
 237                               ._M_iterator(*this, "this"));
 238         --_M_current;
 239         return *this;
 240       }
 241
 242       /**
 243        *  @brief Iterator postdecrement
 244        *  @pre iterator is decrementable
 245        */
 246       _Safe_iterator
 247       operator--(int)
 248       {
 249         _GLIBCXX_DEBUG_VERIFY(this->_M_decrementable(),
 250                               _M_message(__msg_bad_dec)
 251                               ._M_iterator(*this, "this"));
 252         _Safe_iterator __tmp(*this);
 253         --_M_current;
 254         return __tmp;
 255       }
 256
 257       // ------ Random access iterator requirements ------
 258       reference
 259       operator[](const difference_type& __n) const
 260       {
 261         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(__n)
 262                               && this->_M_can_advance(__n+1),
 263                               _M_message(__msg_iter_subscript_oob)
 264                               ._M_iterator(*this)._M_integer(__n));
 265
 266         return _M_current[__n];
 267       }
 268
 269       _Safe_iterator&
 270       operator+=(const difference_type& __n)
 271       {
 272         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(__n),
 273                               _M_message(__msg_advance_oob)
 274                               ._M_iterator(*this)._M_integer(__n));
 275         _M_current += __n;
 276         return *this;
 277       }
 278
 279       _Safe_iterator
 280       operator+(const difference_type& __n) const
 281       {
 282         _Safe_iterator __tmp(*this);
 283         __tmp += __n;
 284         return __tmp;
 285       }
 286
 287       _Safe_iterator&
 288       operator-=(const difference_type& __n)
 289       {
 290         _GLIBCXX_DEBUG_VERIFY(this->_M_can_advance(-__n),
 291                               _M_message(__msg_retreat_oob)
 292                               ._M_iterator(*this)._M_integer(__n));
 293         _M_current += -__n;
 294         return *this;
 295       }
 296
 297       _Safe_iterator
 298       operator-(const difference_type& __n) const
 299       {
 300         _Safe_iterator __tmp(*this);
 301         __tmp -= __n;
 302         return __tmp;
 303       }
 304
 305       // ------ Utilities ------
 306       /**
 307        * @brief Return the underlying iterator
 308        */
 309       _Iterator
 310       base() const { return _M_current; }
 311
 312       /**
 313        * @brief Conversion to underlying non-debug iterator to allow
 314        * better interaction with non-debug containers.
 315        */
 316       operator _Iterator() const { return _M_current; }
 317
 318       /** Attach iterator to the given sequence. */
 319       void
 320       _M_attach(const _Sequence* __seq)
 321       {
 322         _Safe_iterator_base::_M_attach(const_cast<_Sequence*>(__seq),
 323                                        _M_constant());
 324       }
 325
 326       /** Invalidate the iterator, making it singular. */
 327       void
 328       _M_invalidate();
 329
 330       /// Is the iterator dereferenceable?
 331       bool
 332       _M_dereferenceable() const
 333       { return !this->_M_singular() && !_M_is_end(); }
 334
 335       /// Is the iterator incrementable?
 336       bool
 337       _M_incrementable() const { return this->_M_dereferenceable(); }
 338
 339       // Is the iterator decrementable?
 340       bool
 341       _M_decrementable() const { return !_M_singular() && !_M_is_begin(); }
 342
 343       // Can we advance the iterator @p __n steps (@p __n may be negative)
 344       bool
 345       _M_can_advance(const difference_type& __n) const;
 346
 347       // Is the iterator range [*this, __rhs) valid?
 348       template<typename _Other>
 349         bool
 350         _M_valid_range(const _Safe_iterator<_Other, _Sequence>& __rhs) const;
 351
 352       // The sequence this iterator references.
 353       const _Sequence*
 354       _M_get_sequence() const
 355       { return static_cast<const _Sequence*>(_M_sequence); }
 356
 357     /** Determine the distance between two iterators with some known
 358      *  precision.
 359     */
 360     template<typename _Iterator1, typename _Iterator2>
 361       static pair<difference_type, _Distance_precision>
 362       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs)
 363       {
 364         typedef typename iterator_traits<_Iterator1>::iterator_category
 365           _Category;
 366         return _M_get_distance(__lhs, __rhs, _Category());
 367       }
 368
 369     template<typename _Iterator1, typename _Iterator2>
 370       static pair<difference_type, _Distance_precision>
 371       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs,
 372                       std::random_access_iterator_tag)
 373       {
 374         return std::make_pair(__rhs.base() - __lhs.base(), __dp_exact);
 375       }
 376
 377     template<typename _Iterator1, typename _Iterator2>
 378       static pair<difference_type, _Distance_precision>
 379       _M_get_distance(const _Iterator1& __lhs, const _Iterator2& __rhs,
 380                     std::forward_iterator_tag)
 381       {
 382         return std::make_pair(__lhs.base() == __rhs.base()? 0 : 1,
 383                               __dp_equality);
 384       }
 385
 386       /// Is this iterator equal to the sequence's begin() iterator?
 387       bool _M_is_begin() const
 388       { return *this == static_cast<const _Sequence*>(_M_sequence)->begin(); }
 389
 390       /// Is this iterator equal to the sequence's end() iterator?
 391       bool _M_is_end() const
 392       { return *this == static_cast<const _Sequence*>(_M_sequence)->end(); }
 393     };
 394
 395   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 396     inline bool
 397     operator==(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 398                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 399     {
 400       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 401                             _M_message(__msg_iter_compare_bad)
 402                             ._M_iterator(__lhs, "lhs")
 403                             ._M_iterator(__rhs, "rhs"));
 404       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 405                             _M_message(__msg_compare_different)
 406                             ._M_iterator(__lhs, "lhs")
 407                             ._M_iterator(__rhs, "rhs"));
 408       return __lhs.base() == __rhs.base();
 409     }
 410
 411   template<typename _Iterator, typename _Sequence>
 412     inline bool
 413     operator==(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 414                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 415     {
 416       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 417                             _M_message(__msg_iter_compare_bad)
 418                             ._M_iterator(__lhs, "lhs")
 419                             ._M_iterator(__rhs, "rhs"));
 420       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 421                             _M_message(__msg_compare_different)
 422                             ._M_iterator(__lhs, "lhs")
 423                             ._M_iterator(__rhs, "rhs"));
 424       return __lhs.base() == __rhs.base();
 425     }
 426
 427   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 428     inline bool
 429     operator!=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 430                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 431     {
 432       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 433                             _M_message(__msg_iter_compare_bad)
 434                             ._M_iterator(__lhs, "lhs")
 435                             ._M_iterator(__rhs, "rhs"));
 436       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 437                             _M_message(__msg_compare_different)
 438                             ._M_iterator(__lhs, "lhs")
 439                             ._M_iterator(__rhs, "rhs"));
 440       return __lhs.base() != __rhs.base();
 441     }
 442
 443   template<typename _Iterator, typename _Sequence>
 444     inline bool
 445     operator!=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 446                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 447     {
 448       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 449                             _M_message(__msg_iter_compare_bad)
 450                             ._M_iterator(__lhs, "lhs")
 451                             ._M_iterator(__rhs, "rhs"));
 452       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 453                             _M_message(__msg_compare_different)
 454                             ._M_iterator(__lhs, "lhs")
 455                             ._M_iterator(__rhs, "rhs"));
 456       return __lhs.base() != __rhs.base();
 457     }
 458
 459   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 460     inline bool
 461     operator<(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 462               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 463     {
 464       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 465                             _M_message(__msg_iter_order_bad)
 466                             ._M_iterator(__lhs, "lhs")
 467                             ._M_iterator(__rhs, "rhs"));
 468       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 469                             _M_message(__msg_order_different)
 470                             ._M_iterator(__lhs, "lhs")
 471                             ._M_iterator(__rhs, "rhs"));
 472       return __lhs.base() < __rhs.base();
 473     }
 474
 475   template<typename _Iterator, typename _Sequence>
 476     inline bool
 477     operator<(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 478               const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 479     {
 480       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 481                             _M_message(__msg_iter_order_bad)
 482                             ._M_iterator(__lhs, "lhs")
 483                             ._M_iterator(__rhs, "rhs"));
 484       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 485                             _M_message(__msg_order_different)
 486                             ._M_iterator(__lhs, "lhs")
 487                             ._M_iterator(__rhs, "rhs"));
 488       return __lhs.base() < __rhs.base();
 489     }
 490
 491   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 492     inline bool
 493     operator<=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 494                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 495     {
 496       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 497                             _M_message(__msg_iter_order_bad)
 498                             ._M_iterator(__lhs, "lhs")
 499                             ._M_iterator(__rhs, "rhs"));
 500       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 501                             _M_message(__msg_order_different)
 502                             ._M_iterator(__lhs, "lhs")
 503                             ._M_iterator(__rhs, "rhs"));
 504       return __lhs.base() <= __rhs.base();
 505     }
 506
 507   template<typename _Iterator, typename _Sequence>
 508     inline bool
 509     operator<=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 510                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 511     {
 512       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 513                             _M_message(__msg_iter_order_bad)
 514                             ._M_iterator(__lhs, "lhs")
 515                             ._M_iterator(__rhs, "rhs"));
 516       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 517                             _M_message(__msg_order_different)
 518                             ._M_iterator(__lhs, "lhs")
 519                             ._M_iterator(__rhs, "rhs"));
 520       return __lhs.base() <= __rhs.base();
 521     }
 522
 523   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 524     inline bool
 525     operator>(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 526               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 527     {
 528       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 529                             _M_message(__msg_iter_order_bad)
 530                             ._M_iterator(__lhs, "lhs")
 531                             ._M_iterator(__rhs, "rhs"));
 532       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 533                             _M_message(__msg_order_different)
 534                             ._M_iterator(__lhs, "lhs")
 535                             ._M_iterator(__rhs, "rhs"));
 536       return __lhs.base() > __rhs.base();
 537     }
 538
 539   template<typename _Iterator, typename _Sequence>
 540     inline bool
 541     operator>(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 542               const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 543     {
 544       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 545                             _M_message(__msg_iter_order_bad)
 546                             ._M_iterator(__lhs, "lhs")
 547                             ._M_iterator(__rhs, "rhs"));
 548       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 549                             _M_message(__msg_order_different)
 550                             ._M_iterator(__lhs, "lhs")
 551                             ._M_iterator(__rhs, "rhs"));
 552       return __lhs.base() > __rhs.base();
 553     }
 554
 555   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 556     inline bool
 557     operator>=(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 558                const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 559     {
 560       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 561                             _M_message(__msg_iter_order_bad)
 562                             ._M_iterator(__lhs, "lhs")
 563                             ._M_iterator(__rhs, "rhs"));
 564       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 565                             _M_message(__msg_order_different)
 566                             ._M_iterator(__lhs, "lhs")
 567                             ._M_iterator(__rhs, "rhs"));
 568       return __lhs.base() >= __rhs.base();
 569     }
 570
 571   template<typename _Iterator, typename _Sequence>
 572     inline bool
 573     operator>=(const _Safe_iterator<_Iterator, _Sequence>& __lhs,
 574                const _Safe_iterator<_Iterator, _Sequence>& __rhs)
 575     {
 576       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 577                             _M_message(__msg_iter_order_bad)
 578                             ._M_iterator(__lhs, "lhs")
 579                             ._M_iterator(__rhs, "rhs"));
 580       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 581                             _M_message(__msg_order_different)
 582                             ._M_iterator(__lhs, "lhs")
 583                             ._M_iterator(__rhs, "rhs"));
 584       return __lhs.base() >= __rhs.base();
 585     }
 586
 587   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 588   // According to the resolution of DR179 not only the various comparison
 589   // operators but also operator- must accept mixed iterator/const_iterator
 590   // parameters.
 591   template<typename _IteratorL, typename _IteratorR, typename _Sequence>
 592     inline typename _Safe_iterator<_IteratorL, _Sequence>::difference_type
 593     operator-(const _Safe_iterator<_IteratorL, _Sequence>& __lhs,
 594               const _Safe_iterator<_IteratorR, _Sequence>& __rhs)
 595     {
 596       _GLIBCXX_DEBUG_VERIFY(! __lhs._M_singular() && ! __rhs._M_singular(),
 597                             _M_message(__msg_distance_bad)
 598                             ._M_iterator(__lhs, "lhs")
 599                             ._M_iterator(__rhs, "rhs"));
 600       _GLIBCXX_DEBUG_VERIFY(__lhs._M_can_compare(__rhs),
 601                             _M_message(__msg_distance_different)
 602                             ._M_iterator(__lhs, "lhs")
 603                             ._M_iterator(__rhs, "rhs"));
 604       return __lhs.base() - __rhs.base();
 605     }
 606
 607   template<typename _Iterator, typename _Sequence>
 608     inline _Safe_iterator<_Iterator, _Sequence>
 609     operator+(typename _Safe_iterator<_Iterator,_Sequence>::difference_type __n,
 610               const _Safe_iterator<_Iterator, _Sequence>& __i)
 611     { return __i + __n; }
 612 } // namespace __gnu_debug
 613
 614 #ifndef _GLIBCXX_EXPORT_TEMPLATE
 615 #  include <debug/safe_iterator.tcc>
 616 #endif
 617
 618 #endif