libstdc++-v3/include/tr1_impl/hashtable

   1 // Internal header for TR1 unordered_set and unordered_map -*- C++ -*-
   2
   3 // Copyright (C) 2007, 2008, 2009, 2010 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 tr1_impl/hashtable
  26  *  This is an internal header file, included by other library headers.
  27  *  You should not attempt to use it directly.
  28  */
  29
  30 // This header file defines std::tr1::hashtable, which is used to
  31 // implement std::tr1::unordered_set, std::tr1::unordered_map,
  32 // std::tr1::unordered_multiset, and std::tr1::unordered_multimap.
  33 // hashtable has many template parameters, partly to accommodate
  34 // the differences between those four classes and partly to
  35 // accommodate policy choices that go beyond TR1 specifications.
  36
  37 // Class template hashtable attempts to encapsulate all reasonable
  38 // variation among hash tables that use chaining.  It does not handle
  39 // open addressing.
  40
  41 // References:
  42 // M. Austern, "A Proposal to Add Hash Tables to the Standard
  43 //    Library (revision 4)," WG21 Document N1456=03-0039, 2003.
  44 // D. E. Knuth, The Art of Computer Programming, v. 3, Sorting and Searching.
  45 // A. Tavori and V. Dreizin, "Policy-Based Data Structures", 2004.
  46 // http://gcc.gnu.org/onlinedocs/libstdc++/ext/pb_ds/index.html
  47
  48 #include <tr1_impl/hashtable_policy.h>
  49
  50 namespace std
  51 {
  52 namespace tr1
  53 {
  54   // Class template _Hashtable, class definition.
  55
  56   // Meaning of class template _Hashtable's template parameters
  57
  58   // _Key and _Value: arbitrary CopyConstructible types.
  59
  60   // _Allocator: an allocator type ([lib.allocator.requirements]) whose
  61   // value type is Value.  As a conforming extension, we allow for
  62   // value type != Value.
  63
  64   // _ExtractKey: function object that takes a object of type Value
  65   // and returns a value of type _Key.
  66
  67   // _Equal: function object that takes two objects of type k and returns
  68   // a bool-like value that is true if the two objects are considered equal.
  69
  70   // _H1: the hash function.  A unary function object with argument type
  71   // Key and result type size_t.  Return values should be distributed
  72   // over the entire range [0, numeric_limits<size_t>:::max()].
  73
  74   // _H2: the range-hashing function (in the terminology of Tavori and
  75   // Dreizin).  A binary function object whose argument types and result
  76   // type are all size_t.  Given arguments r and N, the return value is
  77   // in the range [0, N).
  78
  79   // _Hash: the ranged hash function (Tavori and Dreizin). A binary function
  80   // whose argument types are _Key and size_t and whose result type is
  81   // size_t.  Given arguments k and N, the return value is in the range
  82   // [0, N).  Default: hash(k, N) = h2(h1(k), N).  If _Hash is anything other
  83   // than the default, _H1 and _H2 are ignored.
  84
  85   // _RehashPolicy: Policy class with three members, all of which govern
  86   // the bucket count. _M_next_bkt(n) returns a bucket count no smaller
  87   // than n.  _M_bkt_for_elements(n) returns a bucket count appropriate
  88   // for an element count of n.  _M_need_rehash(n_bkt, n_elt, n_ins)
  89   // determines whether, if the current bucket count is n_bkt and the
  90   // current element count is n_elt, we need to increase the bucket
  91   // count.  If so, returns make_pair(true, n), where n is the new
  92   // bucket count.  If not, returns make_pair(false, <anything>).
  93
  94   // ??? Right now it is hard-wired that the number of buckets never
  95   // shrinks.  Should we allow _RehashPolicy to change that?
  96
  97   // __cache_hash_code: bool.  true if we store the value of the hash
  98   // function along with the value.  This is a time-space tradeoff.
  99   // Storing it may improve lookup speed by reducing the number of times
 100   // we need to call the Equal function.
 101
 102   // __constant_iterators: bool.  true if iterator and const_iterator are
 103   // both constant iterator types.  This is true for unordered_set and
 104   // unordered_multiset, false for unordered_map and unordered_multimap.
 105
 106   // __unique_keys: bool.  true if the return value of _Hashtable::count(k)
 107   // is always at most one, false if it may be an arbitrary number.  This
 108   // true for unordered_set and unordered_map, false for unordered_multiset
 109   // and unordered_multimap.
 110
 111   template<typename _Key, typename _Value, typename _Allocator,
 112            typename _ExtractKey, typename _Equal,
 113            typename _H1, typename _H2, typename _Hash,
 114            typename _RehashPolicy,
 115            bool __cache_hash_code,
 116            bool __constant_iterators,
 117            bool __unique_keys>
 118     class _Hashtable
 119     : public __detail::_Rehash_base<_RehashPolicy,
 120                                     _Hashtable<_Key, _Value, _Allocator,
 121                                                _ExtractKey,
 122                                                _Equal, _H1, _H2, _Hash,
 123                                                _RehashPolicy,
 124                                                __cache_hash_code,
 125                                                __constant_iterators,
 126                                                __unique_keys> >,
 127       public __detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Equal,
 128                                        _H1, _H2, _Hash, __cache_hash_code>,
 129       public __detail::_Map_base<_Key, _Value, _ExtractKey, __unique_keys,
 130                                  _Hashtable<_Key, _Value, _Allocator,
 131                                             _ExtractKey,
 132                                             _Equal, _H1, _H2, _Hash,
 133                                             _RehashPolicy,
 134                                             __cache_hash_code,
 135                                             __constant_iterators,
 136                                             __unique_keys> >
 137     {
 138     public:
 139       typedef _Allocator                                  allocator_type;
 140       typedef _Value                                      value_type;
 141       typedef _Key                                        key_type;
 142       typedef _Equal                                      key_equal;
 143       // mapped_type, if present, comes from _Map_base.
 144       // hasher, if present, comes from _Hash_code_base.
 145       typedef typename _Allocator::difference_type        difference_type;
 146       typedef typename _Allocator::size_type              size_type;
 147       typedef typename _Allocator::pointer                pointer;
 148       typedef typename _Allocator::const_pointer          const_pointer;
 149       typedef typename _Allocator::reference              reference;
 150       typedef typename _Allocator::const_reference        const_reference;
 151
 152       typedef __detail::_Node_iterator<value_type, __constant_iterators,
 153                                        __cache_hash_code>
 154                                                           local_iterator;
 155       typedef __detail::_Node_const_iterator<value_type,
 156                                              __constant_iterators,
 157                                              __cache_hash_code>
 158                                                           const_local_iterator;
 159
 160       typedef __detail::_Hashtable_iterator<value_type, __constant_iterators,
 161                                             __cache_hash_code>
 162                                                           iterator;
 163       typedef __detail::_Hashtable_const_iterator<value_type,
 164                                                   __constant_iterators,
 165                                                   __cache_hash_code>
 166                                                           const_iterator;
 167
 168       template<typename _Key2, typename _Value2, typename _Ex2, bool __unique2,
 169                typename _Hashtable2>
 170         friend struct __detail::_Map_base;
 171
 172     private:
 173       typedef __detail::_Hash_node<_Value, __cache_hash_code> _Node;
 174       typedef typename _Allocator::template rebind<_Node>::other
 175                                                         _Node_allocator_type;
 176       typedef typename _Allocator::template rebind<_Node*>::other
 177                                                         _Bucket_allocator_type;
 178
 179       typedef typename _Allocator::template rebind<_Value>::other
 180                                                         _Value_allocator_type;
 181
 182       _Node_allocator_type   _M_node_allocator;
 183       _Node**                _M_buckets;
 184       size_type              _M_bucket_count;
 185       size_type              _M_element_count;
 186       _RehashPolicy          _M_rehash_policy;
 187
 188       _Node*
 189       _M_allocate_node(const value_type& __v);
 190
 191       void
 192       _M_deallocate_node(_Node* __n);
 193
 194       void
 195       _M_deallocate_nodes(_Node**, size_type);
 196
 197       _Node**
 198       _M_allocate_buckets(size_type __n);
 199
 200       void
 201       _M_deallocate_buckets(_Node**, size_type __n);
 202
 203     public:
 204       // Constructor, destructor, assignment, swap
 205       _Hashtable(size_type __bucket_hint,
 206                  const _H1&, const _H2&, const _Hash&,
 207                  const _Equal&, const _ExtractKey&,
 208                  const allocator_type&);
 209
 210       template<typename _InputIterator>
 211         _Hashtable(_InputIterator __first, _InputIterator __last,
 212                    size_type __bucket_hint,
 213                    const _H1&, const _H2&, const _Hash&,
 214                    const _Equal&, const _ExtractKey&,
 215                    const allocator_type&);
 216
 217       _Hashtable(const _Hashtable&);
 218
 219       _Hashtable&
 220       operator=(const _Hashtable&);
 221
 222       ~_Hashtable();
 223
 224       void swap(_Hashtable&);
 225
 226       // Basic container operations
 227       iterator
 228       begin()
 229       {
 230         iterator __i(_M_buckets);
 231         if (!__i._M_cur_node)
 232           __i._M_incr_bucket();
 233         return __i;
 234       }
 235
 236       const_iterator
 237       begin() const
 238       {
 239         const_iterator __i(_M_buckets);
 240         if (!__i._M_cur_node)
 241           __i._M_incr_bucket();
 242         return __i;
 243       }
 244
 245       iterator
 246       end()
 247       { return iterator(_M_buckets + _M_bucket_count); }
 248
 249       const_iterator
 250       end() const
 251       { return const_iterator(_M_buckets + _M_bucket_count); }
 252
 253       size_type
 254       size() const
 255       { return _M_element_count; }
 256
 257       bool
 258       empty() const
 259       { return size() == 0; }
 260
 261       allocator_type
 262       get_allocator() const
 263       { return allocator_type(_M_node_allocator); }
 264
 265       _Value_allocator_type
 266       _M_get_Value_allocator() const
 267       { return _Value_allocator_type(_M_node_allocator); }
 268
 269       size_type
 270       max_size() const
 271       { return _M_node_allocator.max_size(); }
 272
 273       // Observers
 274       key_equal
 275       key_eq() const
 276       { return this->_M_eq; }
 277
 278       // hash_function, if present, comes from _Hash_code_base.
 279
 280       // Bucket operations
 281       size_type
 282       bucket_count() const
 283       { return _M_bucket_count; }
 284
 285       size_type
 286       max_bucket_count() const
 287       { return max_size(); }
 288
 289       size_type
 290       bucket_size(size_type __n) const
 291       { return std::distance(begin(__n), end(__n)); }
 292
 293       size_type
 294       bucket(const key_type& __k) const
 295       {
 296         return this->_M_bucket_index(__k, this->_M_hash_code(__k),
 297                                      bucket_count());
 298       }
 299
 300       local_iterator
 301       begin(size_type __n)
 302       { return local_iterator(_M_buckets[__n]); }
 303
 304       local_iterator
 305       end(size_type)
 306       { return local_iterator(0); }
 307
 308       const_local_iterator
 309       begin(size_type __n) const
 310       { return const_local_iterator(_M_buckets[__n]); }
 311
 312       const_local_iterator
 313       end(size_type) const
 314       { return const_local_iterator(0); }
 315
 316       float
 317       load_factor() const
 318       {
 319         return static_cast<float>(size()) / static_cast<float>(bucket_count());
 320       }
 321
 322       // max_load_factor, if present, comes from _Rehash_base.
 323
 324       // Generalization of max_load_factor.  Extension, not found in TR1.  Only
 325       // useful if _RehashPolicy is something other than the default.
 326       const _RehashPolicy&
 327       __rehash_policy() const
 328       { return _M_rehash_policy; }
 329
 330       void
 331       __rehash_policy(const _RehashPolicy&);
 332
 333       // Lookup.
 334       iterator
 335       find(const key_type& __k);
 336
 337       const_iterator
 338       find(const key_type& __k) const;
 339
 340       size_type
 341       count(const key_type& __k) const;
 342
 343       std::pair<iterator, iterator>
 344       equal_range(const key_type& __k);
 345
 346       std::pair<const_iterator, const_iterator>
 347       equal_range(const key_type& __k) const;
 348
 349     private:                    // Find, insert and erase helper functions
 350       // ??? This dispatching is a workaround for the fact that we don't
 351       // have partial specialization of member templates; it would be
 352       // better to just specialize insert on __unique_keys.  There may be a
 353       // cleaner workaround.
 354       typedef typename __gnu_cxx::__conditional_type<__unique_keys,
 355                             std::pair<iterator, bool>, iterator>::__type
 356         _Insert_Return_Type;
 357
 358       typedef typename __gnu_cxx::__conditional_type<__unique_keys,
 359                                           std::_Select1st<_Insert_Return_Type>,
 360                                           std::_Identity<_Insert_Return_Type>
 361                                    >::__type
 362         _Insert_Conv_Type;
 363
 364       _Node*
 365       _M_find_node(_Node*, const key_type&,
 366                    typename _Hashtable::_Hash_code_type) const;
 367
 368       iterator
 369       _M_insert_bucket(const value_type&, size_type,
 370                        typename _Hashtable::_Hash_code_type);
 371
 372       std::pair<iterator, bool>
 373       _M_insert(const value_type&, std::tr1::true_type);
 374
 375       iterator
 376       _M_insert(const value_type&, std::tr1::false_type);
 377
 378       void
 379       _M_erase_node(_Node*, _Node**);
 380
 381     public:
 382       // Insert and erase
 383       _Insert_Return_Type
 384       insert(const value_type& __v)
 385       { return _M_insert(__v, std::tr1::integral_constant<bool,
 386                          __unique_keys>()); }
 387
 388       iterator
 389       insert(iterator, const value_type& __v)
 390       { return iterator(_Insert_Conv_Type()(this->insert(__v))); }
 391
 392       const_iterator
 393       insert(const_iterator, const value_type& __v)
 394       { return const_iterator(_Insert_Conv_Type()(this->insert(__v))); }
 395
 396       template<typename _InputIterator>
 397         void
 398         insert(_InputIterator __first, _InputIterator __last);
 399
 400       iterator
 401       erase(iterator);
 402
 403       const_iterator
 404       erase(const_iterator);
 405
 406       size_type
 407       erase(const key_type&);
 408
 409       iterator
 410       erase(iterator, iterator);
 411
 412       const_iterator
 413       erase(const_iterator, const_iterator);
 414
 415       void
 416       clear();
 417
 418       // Set number of buckets to be appropriate for container of n element.
 419       void rehash(size_type __n);
 420
 421     private:
 422       // Unconditionally change size of bucket array to n.
 423       void _M_rehash(size_type __n);
 424     };
 425
 426
 427   // Definitions of class template _Hashtable's out-of-line member functions.
 428   template<typename _Key, typename _Value,
 429            typename _Allocator, typename _ExtractKey, typename _Equal,
 430            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 431            bool __chc, bool __cit, bool __uk>
 432     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 433                         _H1, _H2, _Hash, _RehashPolicy,
 434                         __chc, __cit, __uk>::_Node*
 435     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 436                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 437     _M_allocate_node(const value_type& __v)
 438     {
 439       _Node* __n = _M_node_allocator.allocate(1);
 440       __try
 441         {
 442           _M_get_Value_allocator().construct(&__n->_M_v, __v);
 443           __n->_M_next = 0;
 444           return __n;
 445         }
 446       __catch(...)
 447         {
 448           _M_node_allocator.deallocate(__n, 1);
 449           __throw_exception_again;
 450         }
 451     }
 452
 453   template<typename _Key, typename _Value,
 454            typename _Allocator, typename _ExtractKey, typename _Equal,
 455            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 456            bool __chc, bool __cit, bool __uk>
 457     void
 458     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 459                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 460     _M_deallocate_node(_Node* __n)
 461     {
 462       _M_get_Value_allocator().destroy(&__n->_M_v);
 463       _M_node_allocator.deallocate(__n, 1);
 464     }
 465
 466   template<typename _Key, typename _Value,
 467            typename _Allocator, typename _ExtractKey, typename _Equal,
 468            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 469            bool __chc, bool __cit, bool __uk>
 470     void
 471     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 472                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 473     _M_deallocate_nodes(_Node** __array, size_type __n)
 474     {
 475       for (size_type __i = 0; __i < __n; ++__i)
 476         {
 477           _Node* __p = __array[__i];
 478           while (__p)
 479             {
 480               _Node* __tmp = __p;
 481               __p = __p->_M_next;
 482               _M_deallocate_node(__tmp);
 483             }
 484           __array[__i] = 0;
 485         }
 486     }
 487
 488   template<typename _Key, typename _Value,
 489            typename _Allocator, typename _ExtractKey, typename _Equal,
 490            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 491            bool __chc, bool __cit, bool __uk>
 492     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 493                         _H1, _H2, _Hash, _RehashPolicy,
 494                         __chc, __cit, __uk>::_Node**
 495     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 496                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 497     _M_allocate_buckets(size_type __n)
 498     {
 499       _Bucket_allocator_type __alloc(_M_node_allocator);
 500
 501       // We allocate one extra bucket to hold a sentinel, an arbitrary
 502       // non-null pointer.  Iterator increment relies on this.
 503       _Node** __p = __alloc.allocate(__n + 1);
 504       std::fill(__p, __p + __n, (_Node*) 0);
 505       __p[__n] = reinterpret_cast<_Node*>(0x1000);
 506       return __p;
 507     }
 508
 509   template<typename _Key, typename _Value,
 510            typename _Allocator, typename _ExtractKey, typename _Equal,
 511            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 512            bool __chc, bool __cit, bool __uk>
 513     void
 514     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 515                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 516     _M_deallocate_buckets(_Node** __p, size_type __n)
 517     {
 518       _Bucket_allocator_type __alloc(_M_node_allocator);
 519       __alloc.deallocate(__p, __n + 1);
 520     }
 521
 522   template<typename _Key, typename _Value,
 523            typename _Allocator, typename _ExtractKey, typename _Equal,
 524            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 525            bool __chc, bool __cit, bool __uk>
 526     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 527                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 528     _Hashtable(size_type __bucket_hint,
 529                const _H1& __h1, const _H2& __h2, const _Hash& __h,
 530                const _Equal& __eq, const _ExtractKey& __exk,
 531                const allocator_type& __a)
 532     : __detail::_Rehash_base<_RehashPolicy, _Hashtable>(),
 533       __detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Equal,
 534                                 _H1, _H2, _Hash, __chc>(__exk, __eq,
 535                                                         __h1, __h2, __h),
 536       __detail::_Map_base<_Key, _Value, _ExtractKey, __uk, _Hashtable>(),
 537       _M_node_allocator(__a),
 538       _M_bucket_count(0),
 539       _M_element_count(0),
 540       _M_rehash_policy()
 541     {
 542       _M_bucket_count = _M_rehash_policy._M_next_bkt(__bucket_hint);
 543       _M_buckets = _M_allocate_buckets(_M_bucket_count);
 544     }
 545
 546   template<typename _Key, typename _Value,
 547            typename _Allocator, typename _ExtractKey, typename _Equal,
 548            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 549            bool __chc, bool __cit, bool __uk>
 550     template<typename _InputIterator>
 551       _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 552                  _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 553       _Hashtable(_InputIterator __f, _InputIterator __l,
 554                  size_type __bucket_hint,
 555                  const _H1& __h1, const _H2& __h2, const _Hash& __h,
 556                  const _Equal& __eq, const _ExtractKey& __exk,
 557                  const allocator_type& __a)
 558       : __detail::_Rehash_base<_RehashPolicy, _Hashtable>(),
 559         __detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Equal,
 560                                   _H1, _H2, _Hash, __chc>(__exk, __eq,
 561                                                           __h1, __h2, __h),
 562         __detail::_Map_base<_Key, _Value, _ExtractKey, __uk, _Hashtable>(),
 563         _M_node_allocator(__a),
 564         _M_bucket_count(0),
 565         _M_element_count(0),
 566         _M_rehash_policy()
 567       {
 568         _M_bucket_count = std::max(_M_rehash_policy._M_next_bkt(__bucket_hint),
 569                                    _M_rehash_policy.
 570                                    _M_bkt_for_elements(__detail::
 571                                                        __distance_fw(__f,
 572                                                                      __l)));
 573         _M_buckets = _M_allocate_buckets(_M_bucket_count);
 574         __try
 575           {
 576             for (; __f != __l; ++__f)
 577               this->insert(*__f);
 578           }
 579         __catch(...)
 580           {
 581             clear();
 582             _M_deallocate_buckets(_M_buckets, _M_bucket_count);
 583             __throw_exception_again;
 584           }
 585       }
 586
 587   template<typename _Key, typename _Value,
 588            typename _Allocator, typename _ExtractKey, typename _Equal,
 589            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 590            bool __chc, bool __cit, bool __uk>
 591     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 592                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 593     _Hashtable(const _Hashtable& __ht)
 594     : __detail::_Rehash_base<_RehashPolicy, _Hashtable>(__ht),
 595       __detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Equal,
 596                                 _H1, _H2, _Hash, __chc>(__ht),
 597       __detail::_Map_base<_Key, _Value, _ExtractKey, __uk, _Hashtable>(__ht),
 598       _M_node_allocator(__ht._M_node_allocator),
 599       _M_bucket_count(__ht._M_bucket_count),
 600       _M_element_count(__ht._M_element_count),
 601       _M_rehash_policy(__ht._M_rehash_policy)
 602     {
 603       _M_buckets = _M_allocate_buckets(_M_bucket_count);
 604       __try
 605         {
 606           for (size_type __i = 0; __i < __ht._M_bucket_count; ++__i)
 607             {
 608               _Node* __n = __ht._M_buckets[__i];
 609               _Node** __tail = _M_buckets + __i;
 610               while (__n)
 611                 {
 612                   *__tail = _M_allocate_node(__n->_M_v);
 613                   this->_M_copy_code(*__tail, __n);
 614                   __tail = &((*__tail)->_M_next);
 615                   __n = __n->_M_next;
 616                 }
 617             }
 618         }
 619       __catch(...)
 620         {
 621           clear();
 622           _M_deallocate_buckets(_M_buckets, _M_bucket_count);
 623           __throw_exception_again;
 624         }
 625     }
 626
 627   template<typename _Key, typename _Value,
 628            typename _Allocator, typename _ExtractKey, typename _Equal,
 629            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 630            bool __chc, bool __cit, bool __uk>
 631     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 632                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>&
 633     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 634                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 635     operator=(const _Hashtable& __ht)
 636     {
 637       _Hashtable __tmp(__ht);
 638       this->swap(__tmp);
 639       return *this;
 640     }
 641
 642   template<typename _Key, typename _Value,
 643            typename _Allocator, typename _ExtractKey, typename _Equal,
 644            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 645            bool __chc, bool __cit, bool __uk>
 646     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 647                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 648     ~_Hashtable()
 649     {
 650       clear();
 651       _M_deallocate_buckets(_M_buckets, _M_bucket_count);
 652     }
 653
 654   template<typename _Key, typename _Value,
 655            typename _Allocator, typename _ExtractKey, typename _Equal,
 656            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 657            bool __chc, bool __cit, bool __uk>
 658     void
 659     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 660                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 661     swap(_Hashtable& __x)
 662     {
 663       // The only base class with member variables is hash_code_base.  We
 664       // define _Hash_code_base::_M_swap because different specializations
 665       // have different members.
 666       __detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Equal,
 667         _H1, _H2, _Hash, __chc>::_M_swap(__x);
 668
 669       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 670       // 431. Swapping containers with unequal allocators.
 671       std::__alloc_swap<_Node_allocator_type>::_S_do_it(_M_node_allocator,
 672                                                         __x._M_node_allocator);
 673
 674       std::swap(_M_rehash_policy, __x._M_rehash_policy);
 675       std::swap(_M_buckets, __x._M_buckets);
 676       std::swap(_M_bucket_count, __x._M_bucket_count);
 677       std::swap(_M_element_count, __x._M_element_count);
 678     }
 679
 680   template<typename _Key, typename _Value,
 681            typename _Allocator, typename _ExtractKey, typename _Equal,
 682            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 683            bool __chc, bool __cit, bool __uk>
 684     void
 685     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 686                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 687     __rehash_policy(const _RehashPolicy& __pol)
 688     {
 689       _M_rehash_policy = __pol;
 690       size_type __n_bkt = __pol._M_bkt_for_elements(_M_element_count);
 691       if (__n_bkt > _M_bucket_count)
 692         _M_rehash(__n_bkt);
 693     }
 694
 695   template<typename _Key, typename _Value,
 696            typename _Allocator, typename _ExtractKey, typename _Equal,
 697            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 698            bool __chc, bool __cit, bool __uk>
 699     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 700                         _H1, _H2, _Hash, _RehashPolicy,
 701                         __chc, __cit, __uk>::iterator
 702     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 703                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 704     find(const key_type& __k)
 705     {
 706       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 707       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 708       _Node* __p = _M_find_node(_M_buckets[__n], __k, __code);
 709       return __p ? iterator(__p, _M_buckets + __n) : this->end();
 710     }
 711
 712   template<typename _Key, typename _Value,
 713            typename _Allocator, typename _ExtractKey, typename _Equal,
 714            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 715            bool __chc, bool __cit, bool __uk>
 716     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 717                         _H1, _H2, _Hash, _RehashPolicy,
 718                         __chc, __cit, __uk>::const_iterator
 719     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 720                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 721     find(const key_type& __k) const
 722     {
 723       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 724       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 725       _Node* __p = _M_find_node(_M_buckets[__n], __k, __code);
 726       return __p ? const_iterator(__p, _M_buckets + __n) : this->end();
 727     }
 728
 729   template<typename _Key, typename _Value,
 730            typename _Allocator, typename _ExtractKey, typename _Equal,
 731            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 732            bool __chc, bool __cit, bool __uk>
 733     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 734                         _H1, _H2, _Hash, _RehashPolicy,
 735                         __chc, __cit, __uk>::size_type
 736     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 737                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 738     count(const key_type& __k) const
 739     {
 740       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 741       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 742       std::size_t __result = 0;
 743       for (_Node* __p = _M_buckets[__n]; __p; __p = __p->_M_next)
 744         if (this->_M_compare(__k, __code, __p))
 745           ++__result;
 746       return __result;
 747     }
 748
 749   template<typename _Key, typename _Value,
 750            typename _Allocator, typename _ExtractKey, typename _Equal,
 751            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 752            bool __chc, bool __cit, bool __uk>
 753     std::pair<typename _Hashtable<_Key, _Value, _Allocator,
 754                                   _ExtractKey, _Equal, _H1,
 755                                   _H2, _Hash, _RehashPolicy,
 756                                   __chc, __cit, __uk>::iterator,
 757               typename _Hashtable<_Key, _Value, _Allocator,
 758                                   _ExtractKey, _Equal, _H1,
 759                                   _H2, _Hash, _RehashPolicy,
 760                                   __chc, __cit, __uk>::iterator>
 761     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 762                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 763     equal_range(const key_type& __k)
 764     {
 765       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 766       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 767       _Node** __head = _M_buckets + __n;
 768       _Node* __p = _M_find_node(*__head, __k, __code);
 769
 770       if (__p)
 771         {
 772           _Node* __p1 = __p->_M_next;
 773           for (; __p1; __p1 = __p1->_M_next)
 774             if (!this->_M_compare(__k, __code, __p1))
 775               break;
 776
 777           iterator __first(__p, __head);
 778           iterator __last(__p1, __head);
 779           if (!__p1)
 780             __last._M_incr_bucket();
 781           return std::make_pair(__first, __last);
 782         }
 783       else
 784         return std::make_pair(this->end(), this->end());
 785     }
 786
 787   template<typename _Key, typename _Value,
 788            typename _Allocator, typename _ExtractKey, typename _Equal,
 789            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 790            bool __chc, bool __cit, bool __uk>
 791     std::pair<typename _Hashtable<_Key, _Value, _Allocator,
 792                                   _ExtractKey, _Equal, _H1,
 793                                   _H2, _Hash, _RehashPolicy,
 794                                   __chc, __cit, __uk>::const_iterator,
 795               typename _Hashtable<_Key, _Value, _Allocator,
 796                                   _ExtractKey, _Equal, _H1,
 797                                   _H2, _Hash, _RehashPolicy,
 798                                   __chc, __cit, __uk>::const_iterator>
 799     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 800                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 801     equal_range(const key_type& __k) const
 802     {
 803       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 804       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 805       _Node** __head = _M_buckets + __n;
 806       _Node* __p = _M_find_node(*__head, __k, __code);
 807
 808       if (__p)
 809         {
 810           _Node* __p1 = __p->_M_next;
 811           for (; __p1; __p1 = __p1->_M_next)
 812             if (!this->_M_compare(__k, __code, __p1))
 813               break;
 814
 815           const_iterator __first(__p, __head);
 816           const_iterator __last(__p1, __head);
 817           if (!__p1)
 818             __last._M_incr_bucket();
 819           return std::make_pair(__first, __last);
 820         }
 821       else
 822         return std::make_pair(this->end(), this->end());
 823     }
 824
 825   // Find the node whose key compares equal to k, beginning the search
 826   // at p (usually the head of a bucket).  Return nil if no node is found.
 827   template<typename _Key, typename _Value,
 828            typename _Allocator, typename _ExtractKey, typename _Equal,
 829            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 830            bool __chc, bool __cit, bool __uk>
 831     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey,
 832                         _Equal, _H1, _H2, _Hash, _RehashPolicy,
 833                         __chc, __cit, __uk>::_Node*
 834     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 835                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 836     _M_find_node(_Node* __p, const key_type& __k,
 837                 typename _Hashtable::_Hash_code_type __code) const
 838     {
 839       for (; __p; __p = __p->_M_next)
 840         if (this->_M_compare(__k, __code, __p))
 841           return __p;
 842       return false;
 843     }
 844
 845   // Insert v in bucket n (assumes no element with its key already present).
 846   template<typename _Key, typename _Value,
 847            typename _Allocator, typename _ExtractKey, typename _Equal,
 848            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 849            bool __chc, bool __cit, bool __uk>
 850     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 851                         _H1, _H2, _Hash, _RehashPolicy,
 852                         __chc, __cit, __uk>::iterator
 853     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 854                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 855     _M_insert_bucket(const value_type& __v, size_type __n,
 856                     typename _Hashtable::_Hash_code_type __code)
 857     {
 858       std::pair<bool, std::size_t> __do_rehash
 859         = _M_rehash_policy._M_need_rehash(_M_bucket_count,
 860                                           _M_element_count, 1);
 861
 862       // Allocate the new node before doing the rehash so that we don't
 863       // do a rehash if the allocation throws.
 864       _Node* __new_node = _M_allocate_node(__v);
 865
 866       __try
 867         {
 868           if (__do_rehash.first)
 869             {
 870               const key_type& __k = this->_M_extract(__v);
 871               __n = this->_M_bucket_index(__k, __code, __do_rehash.second);
 872               _M_rehash(__do_rehash.second);
 873             }
 874
 875           __new_node->_M_next = _M_buckets[__n];
 876           this->_M_store_code(__new_node, __code);
 877           _M_buckets[__n] = __new_node;
 878           ++_M_element_count;
 879           return iterator(__new_node, _M_buckets + __n);
 880         }
 881       __catch(...)
 882         {
 883           _M_deallocate_node(__new_node);
 884           __throw_exception_again;
 885         }
 886     }
 887
 888   // Insert v if no element with its key is already present.
 889   template<typename _Key, typename _Value,
 890            typename _Allocator, typename _ExtractKey, typename _Equal,
 891            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 892            bool __chc, bool __cit, bool __uk>
 893     std::pair<typename _Hashtable<_Key, _Value, _Allocator,
 894                                   _ExtractKey, _Equal, _H1,
 895                                   _H2, _Hash, _RehashPolicy,
 896                                   __chc, __cit, __uk>::iterator, bool>
 897     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 898                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 899   _M_insert(const value_type& __v, std::tr1::true_type)
 900     {
 901       const key_type& __k = this->_M_extract(__v);
 902       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 903       size_type __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 904
 905       if (_Node* __p = _M_find_node(_M_buckets[__n], __k, __code))
 906         return std::make_pair(iterator(__p, _M_buckets + __n), false);
 907       return std::make_pair(_M_insert_bucket(__v, __n, __code), true);
 908     }
 909
 910   // Insert v unconditionally.
 911   template<typename _Key, typename _Value,
 912            typename _Allocator, typename _ExtractKey, typename _Equal,
 913            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 914            bool __chc, bool __cit, bool __uk>
 915     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 916                         _H1, _H2, _Hash, _RehashPolicy,
 917                         __chc, __cit, __uk>::iterator
 918     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 919                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 920     _M_insert(const value_type& __v, std::tr1::false_type)
 921     {
 922       std::pair<bool, std::size_t> __do_rehash
 923         = _M_rehash_policy._M_need_rehash(_M_bucket_count,
 924                                           _M_element_count, 1);
 925       if (__do_rehash.first)
 926         _M_rehash(__do_rehash.second);
 927
 928       const key_type& __k = this->_M_extract(__v);
 929       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
 930       size_type __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
 931
 932       // First find the node, avoid leaking new_node if compare throws.
 933       _Node* __prev = _M_find_node(_M_buckets[__n], __k, __code);
 934       _Node* __new_node = _M_allocate_node(__v);
 935
 936       if (__prev)
 937         {
 938           __new_node->_M_next = __prev->_M_next;
 939           __prev->_M_next = __new_node;
 940         }
 941       else
 942         {
 943           __new_node->_M_next = _M_buckets[__n];
 944           _M_buckets[__n] = __new_node;
 945         }
 946       this->_M_store_code(__new_node, __code);
 947
 948       ++_M_element_count;
 949       return iterator(__new_node, _M_buckets + __n);
 950     }
 951
 952   // For erase(iterator) and erase(const_iterator).
 953   template<typename _Key, typename _Value,
 954            typename _Allocator, typename _ExtractKey, typename _Equal,
 955            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 956            bool __chc, bool __cit, bool __uk>
 957     void
 958     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 959                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 960     _M_erase_node(_Node* __p, _Node** __b)
 961     {
 962       _Node* __cur = *__b;
 963       if (__cur == __p)
 964         *__b = __cur->_M_next;
 965       else
 966         {
 967           _Node* __next = __cur->_M_next;
 968           while (__next != __p)
 969             {
 970               __cur = __next;
 971               __next = __cur->_M_next;
 972             }
 973           __cur->_M_next = __next->_M_next;
 974         }
 975
 976       _M_deallocate_node(__p);
 977       --_M_element_count;
 978     }
 979
 980   template<typename _Key, typename _Value,
 981            typename _Allocator, typename _ExtractKey, typename _Equal,
 982            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
 983            bool __chc, bool __cit, bool __uk>
 984     template<typename _InputIterator>
 985       void
 986       _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
 987                  _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
 988       insert(_InputIterator __first, _InputIterator __last)
 989       {
 990         size_type __n_elt = __detail::__distance_fw(__first, __last);
 991         std::pair<bool, std::size_t> __do_rehash
 992           = _M_rehash_policy._M_need_rehash(_M_bucket_count,
 993                                             _M_element_count, __n_elt);
 994         if (__do_rehash.first)
 995           _M_rehash(__do_rehash.second);
 996
 997         for (; __first != __last; ++__first)
 998           this->insert(*__first);
 999       }
1000
1001   template<typename _Key, typename _Value,
1002            typename _Allocator, typename _ExtractKey, typename _Equal,
1003            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1004            bool __chc, bool __cit, bool __uk>
1005     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1006                         _H1, _H2, _Hash, _RehashPolicy,
1007                         __chc, __cit, __uk>::iterator
1008     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1009                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1010     erase(iterator __it)
1011     {
1012       iterator __result = __it;
1013       ++__result;
1014       _M_erase_node(__it._M_cur_node, __it._M_cur_bucket);
1015       return __result;
1016     }
1017
1018   template<typename _Key, typename _Value,
1019            typename _Allocator, typename _ExtractKey, typename _Equal,
1020            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1021            bool __chc, bool __cit, bool __uk>
1022     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1023                         _H1, _H2, _Hash, _RehashPolicy,
1024                         __chc, __cit, __uk>::const_iterator
1025     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1026                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1027     erase(const_iterator __it)
1028     {
1029       const_iterator __result = __it;
1030       ++__result;
1031       _M_erase_node(__it._M_cur_node, __it._M_cur_bucket);
1032       return __result;
1033     }
1034
1035   template<typename _Key, typename _Value,
1036            typename _Allocator, typename _ExtractKey, typename _Equal,
1037            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1038            bool __chc, bool __cit, bool __uk>
1039     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1040                         _H1, _H2, _Hash, _RehashPolicy,
1041                         __chc, __cit, __uk>::size_type
1042     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1043                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1044     erase(const key_type& __k)
1045     {
1046       typename _Hashtable::_Hash_code_type __code = this->_M_hash_code(__k);
1047       std::size_t __n = this->_M_bucket_index(__k, __code, _M_bucket_count);
1048       size_type __result = 0;
1049
1050       _Node** __slot = _M_buckets + __n;
1051       while (*__slot && !this->_M_compare(__k, __code, *__slot))
1052         __slot = &((*__slot)->_M_next);
1053
1054       _Node** __saved_slot = 0;
1055       while (*__slot && this->_M_compare(__k, __code, *__slot))
1056         {
1057           // _GLIBCXX_RESOLVE_LIB_DEFECTS
1058           // 526. Is it undefined if a function in the standard changes
1059           // in parameters?
1060           if (&this->_M_extract((*__slot)->_M_v) != &__k)
1061             {
1062               _Node* __p = *__slot;
1063               *__slot = __p->_M_next;
1064               _M_deallocate_node(__p);
1065               --_M_element_count;
1066               ++__result;
1067             }
1068           else
1069             {
1070               __saved_slot = __slot;
1071               __slot = &((*__slot)->_M_next);
1072             }
1073         }
1074
1075       if (__saved_slot)
1076         {
1077           _Node* __p = *__saved_slot;
1078           *__saved_slot = __p->_M_next;
1079           _M_deallocate_node(__p);
1080           --_M_element_count;
1081           ++__result;
1082         }
1083
1084       return __result;
1085     }
1086
1087   // ??? This could be optimized by taking advantage of the bucket
1088   // structure, but it's not clear that it's worth doing.  It probably
1089   // wouldn't even be an optimization unless the load factor is large.
1090   template<typename _Key, typename _Value,
1091            typename _Allocator, typename _ExtractKey, typename _Equal,
1092            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1093            bool __chc, bool __cit, bool __uk>
1094     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1095                         _H1, _H2, _Hash, _RehashPolicy,
1096                         __chc, __cit, __uk>::iterator
1097     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1098                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1099     erase(iterator __first, iterator __last)
1100     {
1101       while (__first != __last)
1102         __first = this->erase(__first);
1103       return __last;
1104     }
1105
1106   template<typename _Key, typename _Value,
1107            typename _Allocator, typename _ExtractKey, typename _Equal,
1108            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1109            bool __chc, bool __cit, bool __uk>
1110     typename _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1111                         _H1, _H2, _Hash, _RehashPolicy,
1112                         __chc, __cit, __uk>::const_iterator
1113     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1114                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1115     erase(const_iterator __first, const_iterator __last)
1116     {
1117       while (__first != __last)
1118         __first = this->erase(__first);
1119       return __last;
1120     }
1121
1122   template<typename _Key, typename _Value,
1123            typename _Allocator, typename _ExtractKey, typename _Equal,
1124            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1125            bool __chc, bool __cit, bool __uk>
1126     void
1127     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1128                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1129     clear()
1130     {
1131       _M_deallocate_nodes(_M_buckets, _M_bucket_count);
1132       _M_element_count = 0;
1133     }
1134
1135   template<typename _Key, typename _Value,
1136            typename _Allocator, typename _ExtractKey, typename _Equal,
1137            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1138            bool __chc, bool __cit, bool __uk>
1139     void
1140     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1141                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1142     rehash(size_type __n)
1143     {
1144       _M_rehash(std::max(_M_rehash_policy._M_next_bkt(__n),
1145                          _M_rehash_policy._M_bkt_for_elements(_M_element_count
1146                                                               + 1)));
1147     }
1148
1149   template<typename _Key, typename _Value,
1150            typename _Allocator, typename _ExtractKey, typename _Equal,
1151            typename _H1, typename _H2, typename _Hash, typename _RehashPolicy,
1152            bool __chc, bool __cit, bool __uk>
1153     void
1154     _Hashtable<_Key, _Value, _Allocator, _ExtractKey, _Equal,
1155                _H1, _H2, _Hash, _RehashPolicy, __chc, __cit, __uk>::
1156     _M_rehash(size_type __n)
1157     {
1158       _Node** __new_array = _M_allocate_buckets(__n);
1159       __try
1160         {
1161           for (size_type __i = 0; __i < _M_bucket_count; ++__i)
1162             while (_Node* __p = _M_buckets[__i])
1163               {
1164                 std::size_t __new_index = this->_M_bucket_index(__p, __n);
1165                 _M_buckets[__i] = __p->_M_next;
1166                 __p->_M_next = __new_array[__new_index];
1167                 __new_array[__new_index] = __p;
1168               }
1169           _M_deallocate_buckets(_M_buckets, _M_bucket_count);
1170           _M_bucket_count = __n;
1171           _M_buckets = __new_array;
1172         }
1173       __catch(...)
1174         {
1175           // A failure here means that a hash function threw an exception.
1176           // We can't restore the previous state without calling the hash
1177           // function again, so the only sensible recovery is to delete
1178           // everything.
1179           _M_deallocate_nodes(__new_array, __n);
1180           _M_deallocate_buckets(__new_array, __n);
1181           _M_deallocate_nodes(_M_buckets, _M_bucket_count);
1182           _M_element_count = 0;
1183           __throw_exception_again;
1184         }
1185     }
1186 }
1187 }