libstdc++
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00001 // Internal policy header for TR1 unordered_set and unordered_map -*- C++ -*- 00002 00003 // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file tr1_impl/hashtable_policy.h 00026 * This is an internal header file, included by other library headers. 00027 * You should not attempt to use it directly. 00028 */ 00029 00030 namespace std 00031 { 00032 _GLIBCXX_BEGIN_NAMESPACE_TR1 00033 00034 namespace __detail 00035 { 00036 // Helper function: return distance(first, last) for forward 00037 // iterators, or 0 for input iterators. 00038 template<class _Iterator> 00039 inline typename std::iterator_traits<_Iterator>::difference_type 00040 __distance_fw(_Iterator __first, _Iterator __last, 00041 std::input_iterator_tag) 00042 { return 0; } 00043 00044 template<class _Iterator> 00045 inline typename std::iterator_traits<_Iterator>::difference_type 00046 __distance_fw(_Iterator __first, _Iterator __last, 00047 std::forward_iterator_tag) 00048 { return std::distance(__first, __last); } 00049 00050 template<class _Iterator> 00051 inline typename std::iterator_traits<_Iterator>::difference_type 00052 __distance_fw(_Iterator __first, _Iterator __last) 00053 { 00054 typedef typename std::iterator_traits<_Iterator>::iterator_category _Tag; 00055 return __distance_fw(__first, __last, _Tag()); 00056 } 00057 00058 template<typename _RAIter, typename _Tp> 00059 _RAIter 00060 __lower_bound(_RAIter __first, _RAIter __last, const _Tp& __val) 00061 { 00062 typedef typename std::iterator_traits<_RAIter>::difference_type _DType; 00063 00064 _DType __len = __last - __first; 00065 while (__len > 0) 00066 { 00067 _DType __half = __len >> 1; 00068 _RAIter __middle = __first + __half; 00069 if (*__middle < __val) 00070 { 00071 __first = __middle; 00072 ++__first; 00073 __len = __len - __half - 1; 00074 } 00075 else 00076 __len = __half; 00077 } 00078 return __first; 00079 } 00080 00081 // Auxiliary types used for all instantiations of _Hashtable: nodes 00082 // and iterators. 00083 00084 // Nodes, used to wrap elements stored in the hash table. A policy 00085 // template parameter of class template _Hashtable controls whether 00086 // nodes also store a hash code. In some cases (e.g. strings) this 00087 // may be a performance win. 00088 template<typename _Value, bool __cache_hash_code> 00089 struct _Hash_node; 00090 00091 template<typename _Value> 00092 struct _Hash_node<_Value, true> 00093 { 00094 _Value _M_v; 00095 std::size_t _M_hash_code; 00096 _Hash_node* _M_next; 00097 00098 #ifdef _GLIBCXX_INCLUDE_AS_CXX0X 00099 template<typename... _Args> 00100 _Hash_node(_Args&&... __args) 00101 : _M_v(std::forward<_Args>(__args)...), 00102 _M_hash_code(), _M_next() { } 00103 #endif 00104 }; 00105 00106 template<typename _Value> 00107 struct _Hash_node<_Value, false> 00108 { 00109 _Value _M_v; 00110 _Hash_node* _M_next; 00111 00112 #ifdef _GLIBCXX_INCLUDE_AS_CXX0X 00113 template<typename... _Args> 00114 _Hash_node(_Args&&... __args) 00115 : _M_v(std::forward<_Args>(__args)...), 00116 _M_next() { } 00117 #endif 00118 }; 00119 00120 // Local iterators, used to iterate within a bucket but not between 00121 // buckets. 00122 template<typename _Value, bool __cache> 00123 struct _Node_iterator_base 00124 { 00125 _Node_iterator_base(_Hash_node<_Value, __cache>* __p) 00126 : _M_cur(__p) { } 00127 00128 void 00129 _M_incr() 00130 { _M_cur = _M_cur->_M_next; } 00131 00132 _Hash_node<_Value, __cache>* _M_cur; 00133 }; 00134 00135 template<typename _Value, bool __cache> 00136 inline bool 00137 operator==(const _Node_iterator_base<_Value, __cache>& __x, 00138 const _Node_iterator_base<_Value, __cache>& __y) 00139 { return __x._M_cur == __y._M_cur; } 00140 00141 template<typename _Value, bool __cache> 00142 inline bool 00143 operator!=(const _Node_iterator_base<_Value, __cache>& __x, 00144 const _Node_iterator_base<_Value, __cache>& __y) 00145 { return __x._M_cur != __y._M_cur; } 00146 00147 template<typename _Value, bool __constant_iterators, bool __cache> 00148 struct _Node_iterator 00149 : public _Node_iterator_base<_Value, __cache> 00150 { 00151 typedef _Value value_type; 00152 typedef typename 00153 __gnu_cxx::__conditional_type<__constant_iterators, 00154 const _Value*, _Value*>::__type 00155 pointer; 00156 typedef typename 00157 __gnu_cxx::__conditional_type<__constant_iterators, 00158 const _Value&, _Value&>::__type 00159 reference; 00160 typedef std::ptrdiff_t difference_type; 00161 typedef std::forward_iterator_tag iterator_category; 00162 00163 _Node_iterator() 00164 : _Node_iterator_base<_Value, __cache>(0) { } 00165 00166 explicit 00167 _Node_iterator(_Hash_node<_Value, __cache>* __p) 00168 : _Node_iterator_base<_Value, __cache>(__p) { } 00169 00170 reference 00171 operator*() const 00172 { return this->_M_cur->_M_v; } 00173 00174 pointer 00175 operator->() const 00176 { return &this->_M_cur->_M_v; } 00177 00178 _Node_iterator& 00179 operator++() 00180 { 00181 this->_M_incr(); 00182 return *this; 00183 } 00184 00185 _Node_iterator 00186 operator++(int) 00187 { 00188 _Node_iterator __tmp(*this); 00189 this->_M_incr(); 00190 return __tmp; 00191 } 00192 }; 00193 00194 template<typename _Value, bool __constant_iterators, bool __cache> 00195 struct _Node_const_iterator 00196 : public _Node_iterator_base<_Value, __cache> 00197 { 00198 typedef _Value value_type; 00199 typedef const _Value* pointer; 00200 typedef const _Value& reference; 00201 typedef std::ptrdiff_t difference_type; 00202 typedef std::forward_iterator_tag iterator_category; 00203 00204 _Node_const_iterator() 00205 : _Node_iterator_base<_Value, __cache>(0) { } 00206 00207 explicit 00208 _Node_const_iterator(_Hash_node<_Value, __cache>* __p) 00209 : _Node_iterator_base<_Value, __cache>(__p) { } 00210 00211 _Node_const_iterator(const _Node_iterator<_Value, __constant_iterators, 00212 __cache>& __x) 00213 : _Node_iterator_base<_Value, __cache>(__x._M_cur) { } 00214 00215 reference 00216 operator*() const 00217 { return this->_M_cur->_M_v; } 00218 00219 pointer 00220 operator->() const 00221 { return &this->_M_cur->_M_v; } 00222 00223 _Node_const_iterator& 00224 operator++() 00225 { 00226 this->_M_incr(); 00227 return *this; 00228 } 00229 00230 _Node_const_iterator 00231 operator++(int) 00232 { 00233 _Node_const_iterator __tmp(*this); 00234 this->_M_incr(); 00235 return __tmp; 00236 } 00237 }; 00238 00239 template<typename _Value, bool __cache> 00240 struct _Hashtable_iterator_base 00241 { 00242 _Hashtable_iterator_base(_Hash_node<_Value, __cache>* __node, 00243 _Hash_node<_Value, __cache>** __bucket) 00244 : _M_cur_node(__node), _M_cur_bucket(__bucket) { } 00245 00246 void 00247 _M_incr() 00248 { 00249 _M_cur_node = _M_cur_node->_M_next; 00250 if (!_M_cur_node) 00251 _M_incr_bucket(); 00252 } 00253 00254 void 00255 _M_incr_bucket(); 00256 00257 _Hash_node<_Value, __cache>* _M_cur_node; 00258 _Hash_node<_Value, __cache>** _M_cur_bucket; 00259 }; 00260 00261 // Global iterators, used for arbitrary iteration within a hash 00262 // table. Larger and more expensive than local iterators. 00263 template<typename _Value, bool __cache> 00264 void 00265 _Hashtable_iterator_base<_Value, __cache>:: 00266 _M_incr_bucket() 00267 { 00268 ++_M_cur_bucket; 00269 00270 // This loop requires the bucket array to have a non-null sentinel. 00271 while (!*_M_cur_bucket) 00272 ++_M_cur_bucket; 00273 _M_cur_node = *_M_cur_bucket; 00274 } 00275 00276 template<typename _Value, bool __cache> 00277 inline bool 00278 operator==(const _Hashtable_iterator_base<_Value, __cache>& __x, 00279 const _Hashtable_iterator_base<_Value, __cache>& __y) 00280 { return __x._M_cur_node == __y._M_cur_node; } 00281 00282 template<typename _Value, bool __cache> 00283 inline bool 00284 operator!=(const _Hashtable_iterator_base<_Value, __cache>& __x, 00285 const _Hashtable_iterator_base<_Value, __cache>& __y) 00286 { return __x._M_cur_node != __y._M_cur_node; } 00287 00288 template<typename _Value, bool __constant_iterators, bool __cache> 00289 struct _Hashtable_iterator 00290 : public _Hashtable_iterator_base<_Value, __cache> 00291 { 00292 typedef _Value value_type; 00293 typedef typename 00294 __gnu_cxx::__conditional_type<__constant_iterators, 00295 const _Value*, _Value*>::__type 00296 pointer; 00297 typedef typename 00298 __gnu_cxx::__conditional_type<__constant_iterators, 00299 const _Value&, _Value&>::__type 00300 reference; 00301 typedef std::ptrdiff_t difference_type; 00302 typedef std::forward_iterator_tag iterator_category; 00303 00304 _Hashtable_iterator() 00305 : _Hashtable_iterator_base<_Value, __cache>(0, 0) { } 00306 00307 _Hashtable_iterator(_Hash_node<_Value, __cache>* __p, 00308 _Hash_node<_Value, __cache>** __b) 00309 : _Hashtable_iterator_base<_Value, __cache>(__p, __b) { } 00310 00311 explicit 00312 _Hashtable_iterator(_Hash_node<_Value, __cache>** __b) 00313 : _Hashtable_iterator_base<_Value, __cache>(*__b, __b) { } 00314 00315 reference 00316 operator*() const 00317 { return this->_M_cur_node->_M_v; } 00318 00319 pointer 00320 operator->() const 00321 { return &this->_M_cur_node->_M_v; } 00322 00323 _Hashtable_iterator& 00324 operator++() 00325 { 00326 this->_M_incr(); 00327 return *this; 00328 } 00329 00330 _Hashtable_iterator 00331 operator++(int) 00332 { 00333 _Hashtable_iterator __tmp(*this); 00334 this->_M_incr(); 00335 return __tmp; 00336 } 00337 }; 00338 00339 template<typename _Value, bool __constant_iterators, bool __cache> 00340 struct _Hashtable_const_iterator 00341 : public _Hashtable_iterator_base<_Value, __cache> 00342 { 00343 typedef _Value value_type; 00344 typedef const _Value* pointer; 00345 typedef const _Value& reference; 00346 typedef std::ptrdiff_t difference_type; 00347 typedef std::forward_iterator_tag iterator_category; 00348 00349 _Hashtable_const_iterator() 00350 : _Hashtable_iterator_base<_Value, __cache>(0, 0) { } 00351 00352 _Hashtable_const_iterator(_Hash_node<_Value, __cache>* __p, 00353 _Hash_node<_Value, __cache>** __b) 00354 : _Hashtable_iterator_base<_Value, __cache>(__p, __b) { } 00355 00356 explicit 00357 _Hashtable_const_iterator(_Hash_node<_Value, __cache>** __b) 00358 : _Hashtable_iterator_base<_Value, __cache>(*__b, __b) { } 00359 00360 _Hashtable_const_iterator(const _Hashtable_iterator<_Value, 00361 __constant_iterators, __cache>& __x) 00362 : _Hashtable_iterator_base<_Value, __cache>(__x._M_cur_node, 00363 __x._M_cur_bucket) { } 00364 00365 reference 00366 operator*() const 00367 { return this->_M_cur_node->_M_v; } 00368 00369 pointer 00370 operator->() const 00371 { return &this->_M_cur_node->_M_v; } 00372 00373 _Hashtable_const_iterator& 00374 operator++() 00375 { 00376 this->_M_incr(); 00377 return *this; 00378 } 00379 00380 _Hashtable_const_iterator 00381 operator++(int) 00382 { 00383 _Hashtable_const_iterator __tmp(*this); 00384 this->_M_incr(); 00385 return __tmp; 00386 } 00387 }; 00388 00389 00390 // Many of class template _Hashtable's template parameters are policy 00391 // classes. These are defaults for the policies. 00392 00393 // Default range hashing function: use division to fold a large number 00394 // into the range [0, N). 00395 struct _Mod_range_hashing 00396 { 00397 typedef std::size_t first_argument_type; 00398 typedef std::size_t second_argument_type; 00399 typedef std::size_t result_type; 00400 00401 result_type 00402 operator()(first_argument_type __num, second_argument_type __den) const 00403 { return __num % __den; } 00404 }; 00405 00406 // Default ranged hash function H. In principle it should be a 00407 // function object composed from objects of type H1 and H2 such that 00408 // h(k, N) = h2(h1(k), N), but that would mean making extra copies of 00409 // h1 and h2. So instead we'll just use a tag to tell class template 00410 // hashtable to do that composition. 00411 struct _Default_ranged_hash { }; 00412 00413 // Default value for rehash policy. Bucket size is (usually) the 00414 // smallest prime that keeps the load factor small enough. 00415 struct _Prime_rehash_policy 00416 { 00417 _Prime_rehash_policy(float __z = 1.0) 00418 : _M_max_load_factor(__z), _M_growth_factor(2.f), _M_next_resize(0) { } 00419 00420 float 00421 max_load_factor() const 00422 { return _M_max_load_factor; } 00423 00424 // Return a bucket size no smaller than n. 00425 std::size_t 00426 _M_next_bkt(std::size_t __n) const; 00427 00428 // Return a bucket count appropriate for n elements 00429 std::size_t 00430 _M_bkt_for_elements(std::size_t __n) const; 00431 00432 // __n_bkt is current bucket count, __n_elt is current element count, 00433 // and __n_ins is number of elements to be inserted. Do we need to 00434 // increase bucket count? If so, return make_pair(true, n), where n 00435 // is the new bucket count. If not, return make_pair(false, 0). 00436 std::pair<bool, std::size_t> 00437 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt, 00438 std::size_t __n_ins) const; 00439 00440 enum { _S_n_primes = sizeof(unsigned long) != 8 ? 256 : 256 + 48 }; 00441 00442 float _M_max_load_factor; 00443 float _M_growth_factor; 00444 mutable std::size_t _M_next_resize; 00445 }; 00446 00447 extern const unsigned long __prime_list[]; 00448 00449 // XXX This is a hack. There's no good reason for any of 00450 // _Prime_rehash_policy's member functions to be inline. 00451 00452 // Return a prime no smaller than n. 00453 inline std::size_t 00454 _Prime_rehash_policy:: 00455 _M_next_bkt(std::size_t __n) const 00456 { 00457 const unsigned long* __p = __lower_bound(__prime_list, __prime_list 00458 + _S_n_primes, __n); 00459 _M_next_resize = 00460 static_cast<std::size_t>(__builtin_ceil(*__p * _M_max_load_factor)); 00461 return *__p; 00462 } 00463 00464 // Return the smallest prime p such that alpha p >= n, where alpha 00465 // is the load factor. 00466 inline std::size_t 00467 _Prime_rehash_policy:: 00468 _M_bkt_for_elements(std::size_t __n) const 00469 { 00470 const float __min_bkts = __n / _M_max_load_factor; 00471 const unsigned long* __p = __lower_bound(__prime_list, __prime_list 00472 + _S_n_primes, __min_bkts); 00473 _M_next_resize = 00474 static_cast<std::size_t>(__builtin_ceil(*__p * _M_max_load_factor)); 00475 return *__p; 00476 } 00477 00478 // Finds the smallest prime p such that alpha p > __n_elt + __n_ins. 00479 // If p > __n_bkt, return make_pair(true, p); otherwise return 00480 // make_pair(false, 0). In principle this isn't very different from 00481 // _M_bkt_for_elements. 00482 00483 // The only tricky part is that we're caching the element count at 00484 // which we need to rehash, so we don't have to do a floating-point 00485 // multiply for every insertion. 00486 00487 inline std::pair<bool, std::size_t> 00488 _Prime_rehash_policy:: 00489 _M_need_rehash(std::size_t __n_bkt, std::size_t __n_elt, 00490 std::size_t __n_ins) const 00491 { 00492 if (__n_elt + __n_ins > _M_next_resize) 00493 { 00494 float __min_bkts = ((float(__n_ins) + float(__n_elt)) 00495 / _M_max_load_factor); 00496 if (__min_bkts > __n_bkt) 00497 { 00498 __min_bkts = std::max(__min_bkts, _M_growth_factor * __n_bkt); 00499 const unsigned long* __p = 00500 __lower_bound(__prime_list, __prime_list + _S_n_primes, 00501 __min_bkts); 00502 _M_next_resize = static_cast<std::size_t> 00503 (__builtin_ceil(*__p * _M_max_load_factor)); 00504 return std::make_pair(true, *__p); 00505 } 00506 else 00507 { 00508 _M_next_resize = static_cast<std::size_t> 00509 (__builtin_ceil(__n_bkt * _M_max_load_factor)); 00510 return std::make_pair(false, 0); 00511 } 00512 } 00513 else 00514 return std::make_pair(false, 0); 00515 } 00516 00517 // Base classes for std::tr1::_Hashtable. We define these base 00518 // classes because in some cases we want to do different things 00519 // depending on the value of a policy class. In some cases the 00520 // policy class affects which member functions and nested typedefs 00521 // are defined; we handle that by specializing base class templates. 00522 // Several of the base class templates need to access other members 00523 // of class template _Hashtable, so we use the "curiously recurring 00524 // template pattern" for them. 00525 00526 // class template _Map_base. If the hashtable has a value type of the 00527 // form pair<T1, T2> and a key extraction policy that returns the 00528 // first part of the pair, the hashtable gets a mapped_type typedef. 00529 // If it satisfies those criteria and also has unique keys, then it 00530 // also gets an operator[]. 00531 template<typename _Key, typename _Value, typename _Ex, bool __unique, 00532 typename _Hashtable> 00533 struct _Map_base { }; 00534 00535 template<typename _Key, typename _Pair, typename _Hashtable> 00536 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, false, _Hashtable> 00537 { 00538 typedef typename _Pair::second_type mapped_type; 00539 }; 00540 00541 template<typename _Key, typename _Pair, typename _Hashtable> 00542 struct _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable> 00543 { 00544 typedef typename _Pair::second_type mapped_type; 00545 00546 mapped_type& 00547 operator[](const _Key& __k); 00548 00549 #ifdef _GLIBCXX_INCLUDE_AS_CXX0X 00550 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00551 // DR 761. unordered_map needs an at() member function. 00552 mapped_type& 00553 at(const _Key& __k); 00554 00555 const mapped_type& 00556 at(const _Key& __k) const; 00557 #endif 00558 }; 00559 00560 template<typename _Key, typename _Pair, typename _Hashtable> 00561 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>, 00562 true, _Hashtable>::mapped_type& 00563 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>:: 00564 operator[](const _Key& __k) 00565 { 00566 _Hashtable* __h = static_cast<_Hashtable*>(this); 00567 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k); 00568 std::size_t __n = __h->_M_bucket_index(__k, __code, 00569 __h->_M_bucket_count); 00570 00571 typename _Hashtable::_Node* __p = 00572 __h->_M_find_node(__h->_M_buckets[__n], __k, __code); 00573 if (!__p) 00574 return __h->_M_insert_bucket(std::make_pair(__k, mapped_type()), 00575 __n, __code)->second; 00576 return (__p->_M_v).second; 00577 } 00578 00579 #ifdef _GLIBCXX_INCLUDE_AS_CXX0X 00580 template<typename _Key, typename _Pair, typename _Hashtable> 00581 typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>, 00582 true, _Hashtable>::mapped_type& 00583 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>:: 00584 at(const _Key& __k) 00585 { 00586 _Hashtable* __h = static_cast<_Hashtable*>(this); 00587 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k); 00588 std::size_t __n = __h->_M_bucket_index(__k, __code, 00589 __h->_M_bucket_count); 00590 00591 typename _Hashtable::_Node* __p = 00592 __h->_M_find_node(__h->_M_buckets[__n], __k, __code); 00593 if (!__p) 00594 __throw_out_of_range(__N("_Map_base::at")); 00595 return (__p->_M_v).second; 00596 } 00597 00598 template<typename _Key, typename _Pair, typename _Hashtable> 00599 const typename _Map_base<_Key, _Pair, std::_Select1st<_Pair>, 00600 true, _Hashtable>::mapped_type& 00601 _Map_base<_Key, _Pair, std::_Select1st<_Pair>, true, _Hashtable>:: 00602 at(const _Key& __k) const 00603 { 00604 const _Hashtable* __h = static_cast<const _Hashtable*>(this); 00605 typename _Hashtable::_Hash_code_type __code = __h->_M_hash_code(__k); 00606 std::size_t __n = __h->_M_bucket_index(__k, __code, 00607 __h->_M_bucket_count); 00608 00609 typename _Hashtable::_Node* __p = 00610 __h->_M_find_node(__h->_M_buckets[__n], __k, __code); 00611 if (!__p) 00612 __throw_out_of_range(__N("_Map_base::at")); 00613 return (__p->_M_v).second; 00614 } 00615 #endif 00616 00617 // class template _Rehash_base. Give hashtable the max_load_factor 00618 // functions iff the rehash policy is _Prime_rehash_policy. 00619 template<typename _RehashPolicy, typename _Hashtable> 00620 struct _Rehash_base { }; 00621 00622 template<typename _Hashtable> 00623 struct _Rehash_base<_Prime_rehash_policy, _Hashtable> 00624 { 00625 float 00626 max_load_factor() const 00627 { 00628 const _Hashtable* __this = static_cast<const _Hashtable*>(this); 00629 return __this->__rehash_policy().max_load_factor(); 00630 } 00631 00632 void 00633 max_load_factor(float __z) 00634 { 00635 _Hashtable* __this = static_cast<_Hashtable*>(this); 00636 __this->__rehash_policy(_Prime_rehash_policy(__z)); 00637 } 00638 }; 00639 00640 // Class template _Hash_code_base. Encapsulates two policy issues that 00641 // aren't quite orthogonal. 00642 // (1) the difference between using a ranged hash function and using 00643 // the combination of a hash function and a range-hashing function. 00644 // In the former case we don't have such things as hash codes, so 00645 // we have a dummy type as placeholder. 00646 // (2) Whether or not we cache hash codes. Caching hash codes is 00647 // meaningless if we have a ranged hash function. 00648 // We also put the key extraction and equality comparison function 00649 // objects here, for convenience. 00650 00651 // Primary template: unused except as a hook for specializations. 00652 template<typename _Key, typename _Value, 00653 typename _ExtractKey, typename _Equal, 00654 typename _H1, typename _H2, typename _Hash, 00655 bool __cache_hash_code> 00656 struct _Hash_code_base; 00657 00658 // Specialization: ranged hash function, no caching hash codes. H1 00659 // and H2 are provided but ignored. We define a dummy hash code type. 00660 template<typename _Key, typename _Value, 00661 typename _ExtractKey, typename _Equal, 00662 typename _H1, typename _H2, typename _Hash> 00663 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, 00664 _Hash, false> 00665 { 00666 protected: 00667 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq, 00668 const _H1&, const _H2&, const _Hash& __h) 00669 : _M_extract(__ex), _M_eq(__eq), _M_ranged_hash(__h) { } 00670 00671 typedef void* _Hash_code_type; 00672 00673 _Hash_code_type 00674 _M_hash_code(const _Key& __key) const 00675 { return 0; } 00676 00677 std::size_t 00678 _M_bucket_index(const _Key& __k, _Hash_code_type, 00679 std::size_t __n) const 00680 { return _M_ranged_hash(__k, __n); } 00681 00682 std::size_t 00683 _M_bucket_index(const _Hash_node<_Value, false>* __p, 00684 std::size_t __n) const 00685 { return _M_ranged_hash(_M_extract(__p->_M_v), __n); } 00686 00687 bool 00688 _M_compare(const _Key& __k, _Hash_code_type, 00689 _Hash_node<_Value, false>* __n) const 00690 { return _M_eq(__k, _M_extract(__n->_M_v)); } 00691 00692 void 00693 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const 00694 { } 00695 00696 void 00697 _M_copy_code(_Hash_node<_Value, false>*, 00698 const _Hash_node<_Value, false>*) const 00699 { } 00700 00701 void 00702 _M_swap(_Hash_code_base& __x) 00703 { 00704 std::swap(_M_extract, __x._M_extract); 00705 std::swap(_M_eq, __x._M_eq); 00706 std::swap(_M_ranged_hash, __x._M_ranged_hash); 00707 } 00708 00709 protected: 00710 _ExtractKey _M_extract; 00711 _Equal _M_eq; 00712 _Hash _M_ranged_hash; 00713 }; 00714 00715 00716 // No specialization for ranged hash function while caching hash codes. 00717 // That combination is meaningless, and trying to do it is an error. 00718 00719 00720 // Specialization: ranged hash function, cache hash codes. This 00721 // combination is meaningless, so we provide only a declaration 00722 // and no definition. 00723 template<typename _Key, typename _Value, 00724 typename _ExtractKey, typename _Equal, 00725 typename _H1, typename _H2, typename _Hash> 00726 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, 00727 _Hash, true>; 00728 00729 // Specialization: hash function and range-hashing function, no 00730 // caching of hash codes. H is provided but ignored. Provides 00731 // typedef and accessor required by TR1. 00732 template<typename _Key, typename _Value, 00733 typename _ExtractKey, typename _Equal, 00734 typename _H1, typename _H2> 00735 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, 00736 _Default_ranged_hash, false> 00737 { 00738 typedef _H1 hasher; 00739 00740 hasher 00741 hash_function() const 00742 { return _M_h1; } 00743 00744 protected: 00745 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq, 00746 const _H1& __h1, const _H2& __h2, 00747 const _Default_ranged_hash&) 00748 : _M_extract(__ex), _M_eq(__eq), _M_h1(__h1), _M_h2(__h2) { } 00749 00750 typedef std::size_t _Hash_code_type; 00751 00752 _Hash_code_type 00753 _M_hash_code(const _Key& __k) const 00754 { return _M_h1(__k); } 00755 00756 std::size_t 00757 _M_bucket_index(const _Key&, _Hash_code_type __c, 00758 std::size_t __n) const 00759 { return _M_h2(__c, __n); } 00760 00761 std::size_t 00762 _M_bucket_index(const _Hash_node<_Value, false>* __p, 00763 std::size_t __n) const 00764 { return _M_h2(_M_h1(_M_extract(__p->_M_v)), __n); } 00765 00766 bool 00767 _M_compare(const _Key& __k, _Hash_code_type, 00768 _Hash_node<_Value, false>* __n) const 00769 { return _M_eq(__k, _M_extract(__n->_M_v)); } 00770 00771 void 00772 _M_store_code(_Hash_node<_Value, false>*, _Hash_code_type) const 00773 { } 00774 00775 void 00776 _M_copy_code(_Hash_node<_Value, false>*, 00777 const _Hash_node<_Value, false>*) const 00778 { } 00779 00780 void 00781 _M_swap(_Hash_code_base& __x) 00782 { 00783 std::swap(_M_extract, __x._M_extract); 00784 std::swap(_M_eq, __x._M_eq); 00785 std::swap(_M_h1, __x._M_h1); 00786 std::swap(_M_h2, __x._M_h2); 00787 } 00788 00789 protected: 00790 _ExtractKey _M_extract; 00791 _Equal _M_eq; 00792 _H1 _M_h1; 00793 _H2 _M_h2; 00794 }; 00795 00796 // Specialization: hash function and range-hashing function, 00797 // caching hash codes. H is provided but ignored. Provides 00798 // typedef and accessor required by TR1. 00799 template<typename _Key, typename _Value, 00800 typename _ExtractKey, typename _Equal, 00801 typename _H1, typename _H2> 00802 struct _Hash_code_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, 00803 _Default_ranged_hash, true> 00804 { 00805 typedef _H1 hasher; 00806 00807 hasher 00808 hash_function() const 00809 { return _M_h1; } 00810 00811 protected: 00812 _Hash_code_base(const _ExtractKey& __ex, const _Equal& __eq, 00813 const _H1& __h1, const _H2& __h2, 00814 const _Default_ranged_hash&) 00815 : _M_extract(__ex), _M_eq(__eq), _M_h1(__h1), _M_h2(__h2) { } 00816 00817 typedef std::size_t _Hash_code_type; 00818 00819 _Hash_code_type 00820 _M_hash_code(const _Key& __k) const 00821 { return _M_h1(__k); } 00822 00823 std::size_t 00824 _M_bucket_index(const _Key&, _Hash_code_type __c, 00825 std::size_t __n) const 00826 { return _M_h2(__c, __n); } 00827 00828 std::size_t 00829 _M_bucket_index(const _Hash_node<_Value, true>* __p, 00830 std::size_t __n) const 00831 { return _M_h2(__p->_M_hash_code, __n); } 00832 00833 bool 00834 _M_compare(const _Key& __k, _Hash_code_type __c, 00835 _Hash_node<_Value, true>* __n) const 00836 { return __c == __n->_M_hash_code && _M_eq(__k, _M_extract(__n->_M_v)); } 00837 00838 void 00839 _M_store_code(_Hash_node<_Value, true>* __n, _Hash_code_type __c) const 00840 { __n->_M_hash_code = __c; } 00841 00842 void 00843 _M_copy_code(_Hash_node<_Value, true>* __to, 00844 const _Hash_node<_Value, true>* __from) const 00845 { __to->_M_hash_code = __from->_M_hash_code; } 00846 00847 void 00848 _M_swap(_Hash_code_base& __x) 00849 { 00850 std::swap(_M_extract, __x._M_extract); 00851 std::swap(_M_eq, __x._M_eq); 00852 std::swap(_M_h1, __x._M_h1); 00853 std::swap(_M_h2, __x._M_h2); 00854 } 00855 00856 protected: 00857 _ExtractKey _M_extract; 00858 _Equal _M_eq; 00859 _H1 _M_h1; 00860 _H2 _M_h2; 00861 }; 00862 } // namespace __detail 00863 00864 _GLIBCXX_END_NAMESPACE_TR1 00865 }