libstdc++-v3/include/debug/debug.h

   1 // Debugging support implementation -*- C++ -*-
   2
   3 // Copyright (C) 2003, 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, 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_DEBUG_H
  32 #define _GLIBCXX_DEBUG_DEBUG_H 1
  33
  34 /**
  35  * Macros used by the implementation to verify certain
  36  * properties. These macros may only be used directly by the debug
  37  * wrappers. Note that these are macros (instead of the more obviously
  38  * "correct" choice of making them functions) because we need line and
  39  * file information at the call site, to minimize the distance between
  40  * the user error and where the error is reported.
  41  *
  42  */
  43 #define _GLIBCXX_DEBUG_VERIFY(_Condition,_ErrorMessage)         \
  44   do {                                                                  \
  45     if (! (_Condition))                                                 \
  46       ::__gnu_debug::_Error_formatter::_M_at(__FILE__, __LINE__)        \
  47           ._ErrorMessage._M_error();                                    \
  48   } while (false)
  49
  50 // Verify that [_First, _Last) forms a valid iterator range.
  51 #define __glibcxx_check_valid_range(_First,_Last)                       \
  52 _GLIBCXX_DEBUG_VERIFY(::__gnu_debug::__valid_range(_First, _Last),      \
  53                       _M_message(::__gnu_debug::__msg_valid_range)      \
  54                       ._M_iterator(_First, #_First)                     \
  55                       ._M_iterator(_Last, #_Last))
  56
  57 /** Verify that we can insert into *this with the iterator _Position.
  58  *  Insertion into a container at a specific position requires that
  59  *  the iterator be nonsingular (i.e., either dereferenceable or
  60  *  past-the-end) and that it reference the sequence we are inserting
  61  *  into. Note that this macro is only valid when the container is a
  62  *  _Safe_sequence and the iterator is a _Safe_iterator.
  63 */
  64 #define __glibcxx_check_insert(_Position)                               \
  65 _GLIBCXX_DEBUG_VERIFY(!_Position._M_singular(),                         \
  66                       _M_message(::__gnu_debug::__msg_insert_singular) \
  67                       ._M_sequence(*this, "this")                       \
  68                       ._M_iterator(_Position, #_Position));             \
  69 _GLIBCXX_DEBUG_VERIFY(_Position._M_attached_to(this),                   \
  70                       _M_message(::__gnu_debug::__msg_insert_different) \
  71                       ._M_sequence(*this, "this")                       \
  72                       ._M_iterator(_Position, #_Position))
  73
  74 /** Verify that we can insert the values in the iterator range
  75  *  [_First, _Last) into *this with the iterator _Position.  Insertion
  76  *  into a container at a specific position requires that the iterator
  77  *  be nonsingular (i.e., either dereferenceable or past-the-end),
  78  *  that it reference the sequence we are inserting into, and that the
  79  *  iterator range [_First, Last) is a valid (possibly empty)
  80  *  range. Note that this macro is only valid when the container is a
  81  *  _Safe_sequence and the iterator is a _Safe_iterator.
  82  *
  83  *  @tbd We would like to be able to check for noninterference of
  84  *  _Position and the range [_First, _Last), but that can't (in
  85  *  general) be done.
  86 */
  87 #define __glibcxx_check_insert_range(_Position,_First,_Last)            \
  88 __glibcxx_check_valid_range(_First,_Last);                              \
  89 _GLIBCXX_DEBUG_VERIFY(!_Position._M_singular(),                         \
  90                       _M_message(::__gnu_debug::__msg_insert_singular) \
  91                       ._M_sequence(*this, "this")                       \
  92                       ._M_iterator(_Position, #_Position));             \
  93 _GLIBCXX_DEBUG_VERIFY(_Position._M_attached_to(this),                   \
  94                       _M_message(::__gnu_debug::__msg_insert_different) \
  95                       ._M_sequence(*this, "this")                       \
  96                       ._M_iterator(_Position, #_Position))
  97
  98 /** Verify that we can erase the element referenced by the iterator
  99  * _Position. We can erase the element if the _Position iterator is
 100  * dereferenceable and references this sequence.
 101 */
 102 #define __glibcxx_check_erase(_Position)                                \
 103 _GLIBCXX_DEBUG_VERIFY(_Position._M_dereferenceable(),                   \
 104                       _M_message(::__gnu_debug::__msg_erase_bad)        \
 105                       ._M_sequence(*this, "this")                       \
 106                       ._M_iterator(_Position, #_Position));             \
 107 _GLIBCXX_DEBUG_VERIFY(_Position._M_attached_to(this),                   \
 108                       _M_message(::__gnu_debug::__msg_erase_different) \
 109                       ._M_sequence(*this, "this")                       \
 110                       ._M_iterator(_Position, #_Position))
 111
 112 /** Verify that we can erase the elements in the iterator range
 113  *  [_First, _Last). We can erase the elements if [_First, _Last) is a
 114  *  valid iterator range within this sequence.
 115 */
 116 #define __glibcxx_check_erase_range(_First,_Last)                       \
 117 __glibcxx_check_valid_range(_First,_Last);                              \
 118 _GLIBCXX_DEBUG_VERIFY(_First._M_attached_to(this),                      \
 119                       _M_message(::__gnu_debug::__msg_erase_different) \
 120                       ._M_sequence(*this, "this")                       \
 121                       ._M_iterator(_First, #_First)                     \
 122                       ._M_iterator(_Last, #_Last))
 123
 124 // Verify that the subscript _N is less than the container's size.
 125 #define __glibcxx_check_subscript(_N)                                   \
 126 _GLIBCXX_DEBUG_VERIFY(_N < this->size(),                                \
 127                       _M_message(::__gnu_debug::__msg_subscript_oob) \
 128                       ._M_sequence(*this, "this")                       \
 129                       ._M_integer(_N, #_N)                              \
 130                       ._M_integer(this->size(), "size"))
 131
 132 // Verify that the container is nonempty
 133 #define __glibcxx_check_nonempty()                                      \
 134 _GLIBCXX_DEBUG_VERIFY(! this->empty(),                                  \
 135                       _M_message(::__gnu_debug::__msg_empty)    \
 136                       ._M_sequence(*this, "this"))
 137
 138 // Verify that the < operator for elements in the sequence is a
 139 // StrictWeakOrdering by checking that it is irreflexive.
 140 #define __glibcxx_check_strict_weak_ordering(_First,_Last)      \
 141 _GLIBCXX_DEBUG_ASSERT(_First == _Last || !(*_First < *_First))
 142
 143 // Verify that the predicate is StrictWeakOrdering by checking that it
 144 // is irreflexive.
 145 #define __glibcxx_check_strict_weak_ordering_pred(_First,_Last,_Pred)   \
 146 _GLIBCXX_DEBUG_ASSERT(_First == _Last || !_Pred(*_First, *_First))
 147
 148
 149 // Verify that the iterator range [_First, _Last) is sorted
 150 #define __glibcxx_check_sorted(_First,_Last)                            \
 151 __glibcxx_check_valid_range(_First,_Last);                              \
 152 __glibcxx_check_strict_weak_ordering(_First,_Last);                     \
 153 _GLIBCXX_DEBUG_VERIFY(::__gnu_debug::__check_sorted(_First, _Last),     \
 154                       _M_message(::__gnu_debug::__msg_unsorted) \
 155                       ._M_iterator(_First, #_First)                     \
 156                       ._M_iterator(_Last, #_Last))
 157
 158 /** Verify that the iterator range [_First, _Last) is sorted by the
 159     predicate _Pred. */
 160 #define __glibcxx_check_sorted_pred(_First,_Last,_Pred)                 \
 161 __glibcxx_check_valid_range(_First,_Last);                              \
 162 __glibcxx_check_strict_weak_ordering_pred(_First,_Last,_Pred);          \
 163 _GLIBCXX_DEBUG_VERIFY(::__gnu_debug::__check_sorted(_First, _Last, _Pred), \
 164                       _M_message(::__gnu_debug::__msg_unsorted_pred) \
 165                       ._M_iterator(_First, #_First)                     \
 166                       ._M_iterator(_Last, #_Last)                       \
 167                       ._M_string(#_Pred))
 168
 169 /** Verify that the iterator range [_First, _Last) is partitioned
 170     w.r.t. the value _Value. */
 171 #define __glibcxx_check_partitioned(_First,_Last,_Value)                \
 172 __glibcxx_check_valid_range(_First,_Last);                              \
 173 _GLIBCXX_DEBUG_VERIFY(::__gnu_debug::__check_partitioned(_First, _Last, \
 174                                                          _Value),       \
 175                       _M_message(::__gnu_debug::__msg_unpartitioned) \
 176                       ._M_iterator(_First, #_First)                     \
 177                       ._M_iterator(_Last, #_Last)                       \
 178                       ._M_string(#_Value))
 179
 180 /** Verify that the iterator range [_First, _Last) is partitioned
 181     w.r.t. the value _Value and predicate _Pred. */
 182 #define __glibcxx_check_partitioned_pred(_First,_Last,_Value,_Pred)     \
 183 __glibcxx_check_valid_range(_First,_Last);                              \
 184 _GLIBCXX_DEBUG_VERIFY(::__gnu_debug::__check_partitioned(_First, _Last, \
 185                                                          _Value, _Pred), \
 186                       _M_message(::__gnu_debug::__msg_unpartitioned_pred) \
 187                       ._M_iterator(_First, #_First)                     \
 188                       ._M_iterator(_Last, #_Last)                       \
 189                       ._M_string(#_Pred)                                \
 190                       ._M_string(#_Value))
 191
 192 // Verify that the iterator range [_First, _Last) is a heap
 193 #define __glibcxx_check_heap(_First,_Last)                              \
 194 __glibcxx_check_valid_range(_First,_Last);                              \
 195 _GLIBCXX_DEBUG_VERIFY(::std::__is_heap(_First, _Last),          \
 196                       _M_message(::__gnu_debug::__msg_not_heap) \
 197                       ._M_iterator(_First, #_First)                     \
 198                       ._M_iterator(_Last, #_Last))
 199
 200 /** Verify that the iterator range [_First, _Last) is a heap
 201     w.r.t. the predicate _Pred. */
 202 #define __glibcxx_check_heap_pred(_First,_Last,_Pred)                   \
 203 __glibcxx_check_valid_range(_First,_Last);                              \
 204 _GLIBCXX_DEBUG_VERIFY(::std::__is_heap(_First, _Last, _Pred),           \
 205                       _M_message(::__gnu_debug::__msg_not_heap_pred) \
 206                       ._M_iterator(_First, #_First)                     \
 207                       ._M_iterator(_Last, #_Last)                       \
 208                       ._M_string(#_Pred))
 209
 210 #ifdef _GLIBCXX_DEBUG_PEDANTIC
 211 #  define __glibcxx_check_string(_String) _GLIBCXX_DEBUG_ASSERT(_String != 0)
 212 #  define __glibcxx_check_string_len(_String,_Len) \
 213        _GLIBCXX_DEBUG_ASSERT(_String != 0 || _Len == 0)
 214 #else
 215 #  define __glibcxx_check_string(_String)
 216 #  define __glibcxx_check_string_len(_String,_Len)
 217 #endif
 218
 219 /** Macros used by the implementation outside of debug wrappers to
 220  *  verify certain properties. The __glibcxx_requires_xxx macros are
 221  *  merely wrappers around the __glibcxx_check_xxx wrappers when we
 222  *  are compiling with debug mode, but disappear when we are in
 223  *  release mode so that there is no checking performed in, e.g., the
 224  *  standard library algorithms.
 225 */
 226 #ifdef _GLIBCXX_DEBUG
 227 #  define _GLIBCXX_DEBUG_ASSERT(_Condition) assert(_Condition)
 228
 229 #  ifdef _GLIBXX_DEBUG_PEDANTIC
 230 #    define _GLIBCXX_DEBUG_PEDASSERT(_Condition) assert(_Condition)
 231 #  else
 232 #    define _GLIBCXX_DEBUG_PEDASSERT(_Condition)
 233 #  endif
 234
 235 #  define __glibcxx_requires_cond(_Cond,_Msg) _GLIBCXX_DEBUG_VERIFY(_Cond,_Msg)
 236 #  define __glibcxx_requires_valid_range(_First,_Last) \
 237      __glibcxx_check_valid_range(_First,_Last)
 238 #  define __glibcxx_requires_sorted(_First,_Last) \
 239      __glibcxx_check_sorted(_First,_Last)
 240 #  define __glibcxx_requires_sorted_pred(_First,_Last,_Pred) \
 241      __glibcxx_check_sorted_pred(_First,_Last,_Pred)
 242 #  define __glibcxx_requires_partitioned(_First,_Last,_Value)   \
 243      __glibcxx_check_partitioned(_First,_Last,_Value)
 244 #  define __glibcxx_requires_partitioned_pred(_First,_Last,_Value,_Pred) \
 245      __glibcxx_check_partitioned_pred(_First,_Last,_Value,_Pred)
 246 #  define __glibcxx_requires_heap(_First,_Last) \
 247      __glibcxx_check_heap(_First,_Last)
 248 #  define __glibcxx_requires_heap_pred(_First,_Last,_Pred) \
 249      __glibcxx_check_heap_pred(_First,_Last,_Pred)
 250 #  define __glibcxx_requires_nonempty() __glibcxx_check_nonempty()
 251 #  define __glibcxx_requires_string(_String) __glibcxx_check_string(_String)
 252 #  define __glibcxx_requires_string_len(_String,_Len)   \
 253      __glibcxx_check_string_len(_String,_Len)
 254 #  define __glibcxx_requires_subscript(_N) __glibcxx_check_subscript(_N)
 255 #else
 256 #  define _GLIBCXX_DEBUG_ASSERT(_Condition)
 257 #  define _GLIBCXX_DEBUG_PEDASSERT(_Condition)
 258 #  define __glibcxx_requires_cond(_Cond,_Msg)
 259 #  define __glibcxx_requires_valid_range(_First,_Last)
 260 #  define __glibcxx_requires_sorted(_First,_Last)
 261 #  define __glibcxx_requires_sorted_pred(_First,_Last,_Pred)
 262 #  define __glibcxx_requires_partitioned(_First,_Last,_Value)
 263 #  define __glibcxx_requires_partitioned_pred(_First,_Last,_Value,_Pred)
 264 #  define __glibcxx_requires_heap(_First,_Last)
 265 #  define __glibcxx_requires_heap_pred(_First,_Last,_Pred)
 266 #  define __glibcxx_requires_nonempty()
 267 #  define __glibcxx_requires_string(_String)
 268 #  define __glibcxx_requires_string_len(_String,_Len)
 269 #  define __glibcxx_requires_subscript(_N)
 270 #endif
 271
 272 #include <cassert> // TBD: temporary
 273
 274 #include <stddef.h>                       // for ptrdiff_t
 275 #include <bits/stl_iterator_base_types.h> // for iterator_traits, categories
 276 #include <bits/cpp_type_traits.h>         // for __is_integer
 277
 278 namespace __gnu_debug
 279 {
 280   template<typename _Iterator, typename _Sequence>
 281     class _Safe_iterator;
 282
 283   // An arbitrary iterator pointer is not singular.
 284   inline bool
 285   __check_singular_aux(const void*) { return false; }
 286
 287   // We may have an iterator that derives from _Safe_iterator_base but isn't
 288   // a _Safe_iterator.
 289   template<typename _Iterator>
 290     inline bool
 291     __check_singular(_Iterator& __x)
 292     { return __gnu_debug::__check_singular_aux(&__x); }
 293
 294   /** Non-NULL pointers are nonsingular. */
 295   template<typename _Tp>
 296     inline bool
 297     __check_singular(const _Tp* __ptr)
 298     { return __ptr == 0; }
 299
 300   /** Safe iterators know if they are singular. */
 301   template<typename _Iterator, typename _Sequence>
 302     inline bool
 303     __check_singular(const _Safe_iterator<_Iterator, _Sequence>& __x)
 304     { return __x._M_singular(); }
 305
 306   /** Assume that some arbitrary iterator is dereferenceable, because we
 307       can't prove that it isn't. */
 308   template<typename _Iterator>
 309     inline bool
 310     __check_dereferenceable(_Iterator&)
 311     { return true; }
 312
 313   /** Non-NULL pointers are dereferenceable. */
 314   template<typename _Tp>
 315     inline bool
 316     __check_dereferenceable(const _Tp* __ptr)
 317     { return __ptr; }
 318
 319   /** Safe iterators know if they are singular. */
 320   template<typename _Iterator, typename _Sequence>
 321     inline bool
 322     __check_dereferenceable(const _Safe_iterator<_Iterator, _Sequence>& __x)
 323     { return __x._M_dereferenceable(); }
 324
 325   /** If the distance between two random access iterators is
 326    *  nonnegative, assume the range is valid.
 327   */
 328   template<typename _RandomAccessIterator>
 329     inline bool
 330     __valid_range_aux2(const _RandomAccessIterator& __first,
 331                        const _RandomAccessIterator& __last,
 332                        std::random_access_iterator_tag)
 333     { return __last - __first >= 0; }
 334
 335   /** Can't test for a valid range with input iterators, because
 336    *  iteration may be destructive. So we just assume that the range
 337    *  is valid.
 338   */
 339   template<typename _InputIterator>
 340     inline bool
 341     __valid_range_aux2(const _InputIterator&, const _InputIterator&,
 342                        std::input_iterator_tag)
 343     { return true; }
 344
 345   /** We say that integral types for a valid range, and defer to other
 346    *  routines to realize what to do with integral types instead of
 347    *  iterators.
 348   */
 349   template<typename _Integral>
 350     inline bool
 351     __valid_range_aux(const _Integral&, const _Integral&, __true_type)
 352     { return true; }
 353
 354   /** We have iterators, so figure out what kind of iterators that are
 355    *  to see if we can check the range ahead of time.
 356   */
 357   template<typename _InputIterator>
 358     inline bool
 359     __valid_range_aux(const _InputIterator& __first,
 360                       const _InputIterator& __last, __false_type)
 361   {
 362     typedef typename std::iterator_traits<_InputIterator>::iterator_category
 363       _Category;
 364     return __gnu_debug::__valid_range_aux2(__first, __last, _Category());
 365   }
 366
 367   /** Don't know what these iterators are, or if they are even
 368    *  iterators (we may get an integral type for InputIterator), so
 369    *  see if they are integral and pass them on to the next phase
 370    *  otherwise.
 371   */
 372   template<typename _InputIterator>
 373     inline bool
 374     __valid_range(const _InputIterator& __first, const _InputIterator& __last)
 375     {
 376       typedef typename std::__is_integer<_InputIterator>::__type _Integral;
 377       return __gnu_debug::__valid_range_aux(__first, __last, _Integral());
 378     }
 379
 380   /** Safe iterators know how to check if they form a valid range. */
 381   template<typename _Iterator, typename _Sequence>
 382     inline bool
 383     __valid_range(const _Safe_iterator<_Iterator, _Sequence>& __first,
 384                   const _Safe_iterator<_Iterator, _Sequence>& __last)
 385     { return __first._M_valid_range(__last); }
 386
 387   /* Checks that [first, last) is a valid range, and then returns
 388    * __first. This routine is useful when we can't use a separate
 389    * assertion statement because, e.g., we are in a constructor.
 390   */
 391   template<typename _InputIterator>
 392     inline _InputIterator
 393     __check_valid_range(const _InputIterator& __first,
 394                         const _InputIterator& __last)
 395     {
 396       _GLIBCXX_DEBUG_ASSERT(__gnu_debug::__valid_range(__first, __last));
 397       return __first;
 398     }
 399
 400   /** Checks that __s is non-NULL or __n == 0, and then returns __s. */
 401   template<typename _CharT, typename _Integer>
 402     inline const _CharT*
 403     __check_string(const _CharT* __s, const _Integer& __n)
 404     {
 405 #ifdef _GLIBCXX_DEBUG_PEDANTIC
 406       _GLIBCXX_DEBUG_ASSERT(__s != 0 || __n == 0);
 407 #endif
 408       return __s;
 409     }
 410
 411   /** Checks that __s is non-NULL and then returns __s. */
 412   template<typename _CharT>
 413     inline const _CharT*
 414     __check_string(const _CharT* __s)
 415     {
 416 #ifdef _GLIBCXX_DEBUG_PEDANTIC
 417       _GLIBCXX_DEBUG_ASSERT(__s != 0);
 418 #endif
 419       return __s;
 420     }
 421
 422   // Can't check if an input iterator sequence is sorted, because we
 423   // can't step through the sequence.
 424   template<typename _InputIterator>
 425     inline bool
 426     __check_sorted_aux(const _InputIterator&, const _InputIterator&,
 427                        std::input_iterator_tag)
 428     { return true; }
 429
 430   // Can verify if a forward iterator sequence is in fact sorted using
 431   // std::__is_sorted
 432   template<typename _ForwardIterator>
 433     inline bool
 434     __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
 435                        std::forward_iterator_tag)
 436     {
 437       if (__first == __last)
 438         return true;
 439
 440       _ForwardIterator __next = __first;
 441       for (++__next; __next != __last; __first = __next, ++__next) {
 442         if (*__next < *__first)
 443           return false;
 444       }
 445
 446       return true;
 447     }
 448
 449   // Can't check if an input iterator sequence is sorted, because we can't step
 450   // through the sequence.
 451   template<typename _InputIterator, typename _Predicate>
 452     inline bool
 453     __check_sorted_aux(const _InputIterator&, const _InputIterator&,
 454                        _Predicate, std::input_iterator_tag)
 455     { return true; }
 456
 457   // Can verify if a forward iterator sequence is in fact sorted using
 458   // std::__is_sorted
 459   template<typename _ForwardIterator, typename _Predicate>
 460     inline bool
 461     __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
 462                        _Predicate __pred, std::forward_iterator_tag)
 463     {
 464       if (__first == __last)
 465         return true;
 466
 467       _ForwardIterator __next = __first;
 468       for (++__next; __next != __last; __first = __next, ++__next) {
 469         if (__pred(*__next, *__first))
 470           return false;
 471       }
 472
 473       return true;
 474     }
 475
 476   // Determine if a sequence is sorted.
 477   template<typename _InputIterator>
 478     inline bool
 479     __check_sorted(const _InputIterator& __first, const _InputIterator& __last)
 480     {
 481       typedef typename std::iterator_traits<_InputIterator>::iterator_category
 482         _Category;
 483       return __gnu_debug::__check_sorted_aux(__first, __last, _Category());
 484     }
 485
 486   template<typename _InputIterator, typename _Predicate>
 487     inline bool
 488     __check_sorted(const _InputIterator& __first, const _InputIterator& __last,
 489                    _Predicate __pred)
 490     {
 491       typedef typename std::iterator_traits<_InputIterator>::iterator_category
 492         _Category;
 493       return __gnu_debug::__check_sorted_aux(__first, __last, __pred,
 494                                              _Category());
 495     }
 496
 497   // _GLIBCXX_RESOLVE_LIB_DEFECTS
 498   // 270. Binary search requirements overly strict
 499   // Determine if a sequence is partitioned w.r.t. this element.
 500   template<typename _ForwardIterator, typename _Tp>
 501     inline bool
 502     __check_partitioned(_ForwardIterator __first, _ForwardIterator __last,
 503                         const _Tp& __value)
 504     {
 505       while (__first != __last && *__first < __value)
 506         ++__first;
 507       while (__first != __last && !(*__first < __value))
 508         ++__first;
 509       return __first == __last;
 510     }
 511
 512   // Determine if a sequence is partitioned w.r.t. this element.
 513   template<typename _ForwardIterator, typename _Tp, typename _Pred>
 514     inline bool
 515     __check_partitioned(_ForwardIterator __first, _ForwardIterator __last,
 516                         const _Tp& __value, _Pred __pred)
 517     {
 518       while (__first != __last && __pred(*__first, __value))
 519         ++__first;
 520       while (__first != __last && !__pred(*__first, __value))
 521         ++__first;
 522       return __first == __last;
 523     }
 524 } // namespace __gnu_debug
 525
 526 #ifdef _GLIBCXX_DEBUG
 527 // We need the error formatter
 528 #  include <debug/formatter.h>
 529 #endif
 530
 531 #endif