sso_string_base.h

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00001 // Short-string-optimized versatile string base -*- C++ -*-
00002 
00003 // Copyright (C) 2005, 2006, 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 ext/sso_string_base.h
00026  *  This file is a GNU extension to the Standard C++ Library.
00027  *  This is an internal header file, included by other library headers.
00028  *  You should not attempt to use it directly.
00029  */
00030 
00031 #ifndef _SSO_STRING_BASE_H
00032 #define _SSO_STRING_BASE_H 1
00033 
00034 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00035 
00036   template<typename _CharT, typename _Traits, typename _Alloc>
00037     class __sso_string_base
00038     : protected __vstring_utility<_CharT, _Traits, _Alloc>
00039     {
00040     public:
00041       typedef _Traits                       traits_type;
00042       typedef typename _Traits::char_type           value_type;
00043 
00044       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
00045       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
00046       typedef typename _CharT_alloc_type::size_type     size_type;
00047       
00048     private:
00049       // Data Members:
00050       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
00051                                                             _M_dataplus;
00052       size_type                                             _M_string_length;
00053 
00054       enum { _S_local_capacity = 15 };
00055       
00056       union
00057       {
00058     _CharT           _M_local_data[_S_local_capacity + 1];
00059     size_type        _M_allocated_capacity;
00060       };
00061 
00062       void
00063       _M_data(_CharT* __p)
00064       { _M_dataplus._M_p = __p; }
00065 
00066       void
00067       _M_length(size_type __length)
00068       { _M_string_length = __length; }
00069 
00070       void
00071       _M_capacity(size_type __capacity)
00072       { _M_allocated_capacity = __capacity; }
00073 
00074       bool
00075       _M_is_local() const
00076       { return _M_data() == _M_local_data; }
00077 
00078       // Create & Destroy
00079       _CharT*
00080       _M_create(size_type&, size_type);
00081       
00082       void
00083       _M_dispose()
00084       {
00085     if (!_M_is_local())
00086       _M_destroy(_M_allocated_capacity);
00087       }
00088 
00089       void
00090       _M_destroy(size_type __size) throw()
00091       { _M_get_allocator().deallocate(_M_data(), __size + 1); }
00092 
00093       // _M_construct_aux is used to implement the 21.3.1 para 15 which
00094       // requires special behaviour if _InIterator is an integral type
00095       template<typename _InIterator>
00096         void
00097         _M_construct_aux(_InIterator __beg, _InIterator __end, 
00098              std::__false_type)
00099     {
00100           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
00101           _M_construct(__beg, __end, _Tag());
00102     }
00103 
00104       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00105       // 438. Ambiguity in the "do the right thing" clause
00106       template<typename _Integer>
00107         void
00108         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
00109     { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
00110 
00111       void
00112       _M_construct_aux_2(size_type __req, _CharT __c)
00113       { _M_construct(__req, __c); }
00114 
00115       template<typename _InIterator>
00116         void
00117         _M_construct(_InIterator __beg, _InIterator __end)
00118     {
00119       typedef typename std::__is_integer<_InIterator>::__type _Integral;
00120       _M_construct_aux(__beg, __end, _Integral());
00121         }
00122 
00123       // For Input Iterators, used in istreambuf_iterators, etc.
00124       template<typename _InIterator>
00125         void
00126         _M_construct(_InIterator __beg, _InIterator __end,
00127              std::input_iterator_tag);
00128       
00129       // For forward_iterators up to random_access_iterators, used for
00130       // string::iterator, _CharT*, etc.
00131       template<typename _FwdIterator>
00132         void
00133         _M_construct(_FwdIterator __beg, _FwdIterator __end,
00134              std::forward_iterator_tag);
00135 
00136       void
00137       _M_construct(size_type __req, _CharT __c);
00138 
00139     public:
00140       size_type
00141       _M_max_size() const
00142       { return (_M_get_allocator().max_size() - 1) / 2; }
00143 
00144       _CharT*
00145       _M_data() const
00146       { return _M_dataplus._M_p; }
00147 
00148       size_type
00149       _M_length() const
00150       { return _M_string_length; }
00151 
00152       size_type
00153       _M_capacity() const
00154       {
00155     return _M_is_local() ? size_type(_S_local_capacity)
00156                          : _M_allocated_capacity; 
00157       }
00158 
00159       bool
00160       _M_is_shared() const
00161       { return false; }
00162 
00163       void
00164       _M_set_leaked() { }
00165 
00166       void
00167       _M_leak() { }
00168 
00169       void
00170       _M_set_length(size_type __n)
00171       {
00172     _M_length(__n);
00173     traits_type::assign(_M_data()[__n], _CharT());
00174       }
00175 
00176       __sso_string_base()
00177       : _M_dataplus(_M_local_data)
00178       { _M_set_length(0); }
00179 
00180       __sso_string_base(const _Alloc& __a);
00181 
00182       __sso_string_base(const __sso_string_base& __rcs);
00183 
00184 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00185       __sso_string_base(__sso_string_base&& __rcs);
00186 #endif
00187 
00188       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
00189 
00190       template<typename _InputIterator>
00191         __sso_string_base(_InputIterator __beg, _InputIterator __end,
00192               const _Alloc& __a);
00193 
00194       ~__sso_string_base()
00195       { _M_dispose(); }
00196 
00197       _CharT_alloc_type&
00198       _M_get_allocator()
00199       { return _M_dataplus; }
00200 
00201       const _CharT_alloc_type&
00202       _M_get_allocator() const
00203       { return _M_dataplus; }
00204 
00205       void
00206       _M_swap(__sso_string_base& __rcs);
00207 
00208       void
00209       _M_assign(const __sso_string_base& __rcs);
00210 
00211       void
00212       _M_reserve(size_type __res);
00213 
00214       void
00215       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00216         size_type __len2);
00217 
00218       void
00219       _M_erase(size_type __pos, size_type __n);
00220 
00221       void
00222       _M_clear()
00223       { _M_set_length(0); }
00224 
00225       bool
00226       _M_compare(const __sso_string_base&) const
00227       { return false; }
00228     };
00229 
00230   template<typename _CharT, typename _Traits, typename _Alloc>
00231     void
00232     __sso_string_base<_CharT, _Traits, _Alloc>::
00233     _M_swap(__sso_string_base& __rcs)
00234     {
00235       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00236       // 431. Swapping containers with unequal allocators.
00237       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
00238                              __rcs._M_get_allocator());
00239 
00240       if (_M_is_local())
00241     if (__rcs._M_is_local())
00242       {
00243         if (_M_length() && __rcs._M_length())
00244           {
00245         _CharT __tmp_data[_S_local_capacity + 1];
00246         traits_type::copy(__tmp_data, __rcs._M_local_data,
00247                   _S_local_capacity + 1);
00248         traits_type::copy(__rcs._M_local_data, _M_local_data,
00249                   _S_local_capacity + 1);
00250         traits_type::copy(_M_local_data, __tmp_data,
00251                   _S_local_capacity + 1);
00252           }
00253         else if (__rcs._M_length())
00254           {
00255         traits_type::copy(_M_local_data, __rcs._M_local_data,
00256                   _S_local_capacity + 1);
00257         _M_length(__rcs._M_length());
00258         __rcs._M_set_length(0);
00259         return;
00260           }
00261         else if (_M_length())
00262           {
00263         traits_type::copy(__rcs._M_local_data, _M_local_data,
00264                   _S_local_capacity + 1);
00265         __rcs._M_length(_M_length());
00266         _M_set_length(0);
00267         return;
00268           }
00269       }
00270     else
00271       {
00272         const size_type __tmp_capacity = __rcs._M_allocated_capacity;
00273         traits_type::copy(__rcs._M_local_data, _M_local_data,
00274                   _S_local_capacity + 1);
00275         _M_data(__rcs._M_data());
00276         __rcs._M_data(__rcs._M_local_data);
00277         _M_capacity(__tmp_capacity);
00278       }
00279       else
00280     {
00281       const size_type __tmp_capacity = _M_allocated_capacity;
00282       if (__rcs._M_is_local())
00283         {
00284           traits_type::copy(_M_local_data, __rcs._M_local_data,
00285                 _S_local_capacity + 1);
00286           __rcs._M_data(_M_data());
00287           _M_data(_M_local_data);
00288         }
00289       else
00290         {
00291           _CharT* __tmp_ptr = _M_data();
00292           _M_data(__rcs._M_data());
00293           __rcs._M_data(__tmp_ptr);
00294           _M_capacity(__rcs._M_allocated_capacity);
00295         }
00296       __rcs._M_capacity(__tmp_capacity);
00297     }
00298 
00299       const size_type __tmp_length = _M_length();
00300       _M_length(__rcs._M_length());
00301       __rcs._M_length(__tmp_length);
00302     }
00303 
00304   template<typename _CharT, typename _Traits, typename _Alloc>
00305     _CharT*
00306     __sso_string_base<_CharT, _Traits, _Alloc>::
00307     _M_create(size_type& __capacity, size_type __old_capacity)
00308     {
00309       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00310       // 83.  String::npos vs. string::max_size()
00311       if (__capacity > _M_max_size())
00312     std::__throw_length_error(__N("__sso_string_base::_M_create"));
00313 
00314       // The below implements an exponential growth policy, necessary to
00315       // meet amortized linear time requirements of the library: see
00316       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
00317       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
00318     {
00319       __capacity = 2 * __old_capacity;
00320       // Never allocate a string bigger than max_size.
00321       if (__capacity > _M_max_size())
00322         __capacity = _M_max_size();
00323     }
00324 
00325       // NB: Need an array of char_type[__capacity], plus a terminating
00326       // null char_type() element.
00327       return _M_get_allocator().allocate(__capacity + 1);
00328     }
00329 
00330   template<typename _CharT, typename _Traits, typename _Alloc>
00331     __sso_string_base<_CharT, _Traits, _Alloc>::
00332     __sso_string_base(const _Alloc& __a)
00333     : _M_dataplus(__a, _M_local_data)
00334     { _M_set_length(0); }
00335 
00336   template<typename _CharT, typename _Traits, typename _Alloc>
00337     __sso_string_base<_CharT, _Traits, _Alloc>::
00338     __sso_string_base(const __sso_string_base& __rcs)
00339     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
00340     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
00341 
00342 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00343   template<typename _CharT, typename _Traits, typename _Alloc>
00344     __sso_string_base<_CharT, _Traits, _Alloc>::
00345     __sso_string_base(__sso_string_base&& __rcs)
00346     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
00347     {
00348       if (__rcs._M_is_local())
00349     {
00350       if (__rcs._M_length())
00351         traits_type::copy(_M_local_data, __rcs._M_local_data,
00352                   _S_local_capacity + 1);
00353     }
00354       else
00355     {
00356       _M_data(__rcs._M_data());
00357       _M_capacity(__rcs._M_allocated_capacity);
00358     }
00359 
00360       _M_length(__rcs._M_length());
00361       __rcs._M_length(0);
00362       __rcs._M_data(__rcs._M_local_data);
00363     }
00364 #endif
00365 
00366   template<typename _CharT, typename _Traits, typename _Alloc>
00367     __sso_string_base<_CharT, _Traits, _Alloc>::
00368     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
00369     : _M_dataplus(__a, _M_local_data)
00370     { _M_construct(__n, __c); }
00371 
00372   template<typename _CharT, typename _Traits, typename _Alloc>
00373     template<typename _InputIterator>
00374     __sso_string_base<_CharT, _Traits, _Alloc>::
00375     __sso_string_base(_InputIterator __beg, _InputIterator __end,
00376               const _Alloc& __a)
00377     : _M_dataplus(__a, _M_local_data)
00378     { _M_construct(__beg, __end); }
00379 
00380   // NB: This is the special case for Input Iterators, used in
00381   // istreambuf_iterators, etc.
00382   // Input Iterators have a cost structure very different from
00383   // pointers, calling for a different coding style.
00384   template<typename _CharT, typename _Traits, typename _Alloc>
00385     template<typename _InIterator>
00386       void
00387       __sso_string_base<_CharT, _Traits, _Alloc>::
00388       _M_construct(_InIterator __beg, _InIterator __end,
00389            std::input_iterator_tag)
00390       {
00391     size_type __len = 0;
00392     size_type __capacity = size_type(_S_local_capacity);
00393 
00394     while (__beg != __end && __len < __capacity)
00395       {
00396         _M_data()[__len++] = *__beg;
00397         ++__beg;
00398       }
00399     
00400     __try
00401       {
00402         while (__beg != __end)
00403           {
00404         if (__len == __capacity)
00405           {
00406             // Allocate more space.
00407             __capacity = __len + 1;
00408             _CharT* __another = _M_create(__capacity, __len);
00409             _S_copy(__another, _M_data(), __len);
00410             _M_dispose();
00411             _M_data(__another);
00412             _M_capacity(__capacity);
00413           }
00414         _M_data()[__len++] = *__beg;
00415         ++__beg;
00416           }
00417       }
00418     __catch(...)
00419       {
00420         _M_dispose();
00421         __throw_exception_again;
00422       }
00423 
00424     _M_set_length(__len);
00425       }
00426 
00427   template<typename _CharT, typename _Traits, typename _Alloc>
00428     template<typename _InIterator>
00429       void
00430       __sso_string_base<_CharT, _Traits, _Alloc>::
00431       _M_construct(_InIterator __beg, _InIterator __end,
00432            std::forward_iterator_tag)
00433       {
00434     // NB: Not required, but considered best practice.
00435     if (__is_null_pointer(__beg) && __beg != __end)
00436       std::__throw_logic_error(__N("__sso_string_base::"
00437                        "_M_construct NULL not valid"));
00438 
00439     size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
00440 
00441     if (__dnew > size_type(_S_local_capacity))
00442       {
00443         _M_data(_M_create(__dnew, size_type(0)));
00444         _M_capacity(__dnew);
00445       }
00446 
00447     // Check for out_of_range and length_error exceptions.
00448     __try
00449       { _S_copy_chars(_M_data(), __beg, __end); }
00450     __catch(...)
00451       {
00452         _M_dispose();
00453         __throw_exception_again;
00454       }
00455 
00456     _M_set_length(__dnew);
00457       }
00458 
00459   template<typename _CharT, typename _Traits, typename _Alloc>
00460     void
00461     __sso_string_base<_CharT, _Traits, _Alloc>::
00462     _M_construct(size_type __n, _CharT __c)
00463     {
00464       if (__n > size_type(_S_local_capacity))
00465     {
00466       _M_data(_M_create(__n, size_type(0)));
00467       _M_capacity(__n);
00468     }
00469 
00470       if (__n)
00471     _S_assign(_M_data(), __n, __c);
00472 
00473       _M_set_length(__n);
00474     }
00475 
00476   template<typename _CharT, typename _Traits, typename _Alloc>
00477     void
00478     __sso_string_base<_CharT, _Traits, _Alloc>::
00479     _M_assign(const __sso_string_base& __rcs)
00480     {
00481       if (this != &__rcs)
00482     {
00483       const size_type __rsize = __rcs._M_length();
00484       const size_type __capacity = _M_capacity();
00485 
00486       if (__rsize > __capacity)
00487         {
00488           size_type __new_capacity = __rsize;
00489           _CharT* __tmp = _M_create(__new_capacity, __capacity);
00490           _M_dispose();
00491           _M_data(__tmp);
00492           _M_capacity(__new_capacity);
00493         }
00494 
00495       if (__rsize)
00496         _S_copy(_M_data(), __rcs._M_data(), __rsize);
00497 
00498       _M_set_length(__rsize);
00499     }
00500     }
00501 
00502   template<typename _CharT, typename _Traits, typename _Alloc>
00503     void
00504     __sso_string_base<_CharT, _Traits, _Alloc>::
00505     _M_reserve(size_type __res)
00506     {
00507       // Make sure we don't shrink below the current size.
00508       if (__res < _M_length())
00509     __res = _M_length();
00510 
00511       const size_type __capacity = _M_capacity();
00512       if (__res != __capacity)
00513     {
00514       if (__res > __capacity
00515           || __res > size_type(_S_local_capacity))
00516         {
00517           _CharT* __tmp = _M_create(__res, __capacity);
00518           _S_copy(__tmp, _M_data(), _M_length() + 1);
00519           _M_dispose();
00520           _M_data(__tmp);
00521           _M_capacity(__res);
00522         }
00523       else if (!_M_is_local())
00524         {
00525           _S_copy(_M_local_data, _M_data(), _M_length() + 1);
00526           _M_destroy(__capacity);
00527           _M_data(_M_local_data);
00528         }
00529     }
00530     }
00531 
00532   template<typename _CharT, typename _Traits, typename _Alloc>
00533     void
00534     __sso_string_base<_CharT, _Traits, _Alloc>::
00535     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00536           size_type __len2)
00537     {
00538       const size_type __how_much = _M_length() - __pos - __len1;
00539       
00540       size_type __new_capacity = _M_length() + __len2 - __len1;
00541       _CharT* __r = _M_create(__new_capacity, _M_capacity());
00542 
00543       if (__pos)
00544     _S_copy(__r, _M_data(), __pos);
00545       if (__s && __len2)
00546     _S_copy(__r + __pos, __s, __len2);
00547       if (__how_much)
00548     _S_copy(__r + __pos + __len2,
00549         _M_data() + __pos + __len1, __how_much);
00550       
00551       _M_dispose();
00552       _M_data(__r);
00553       _M_capacity(__new_capacity);
00554     }
00555 
00556   template<typename _CharT, typename _Traits, typename _Alloc>
00557     void
00558     __sso_string_base<_CharT, _Traits, _Alloc>::
00559     _M_erase(size_type __pos, size_type __n)
00560     {
00561       const size_type __how_much = _M_length() - __pos - __n;
00562 
00563       if (__how_much && __n)
00564     _S_move(_M_data() + __pos, _M_data() + __pos + __n,
00565         __how_much);
00566 
00567       _M_set_length(_M_length() - __n);
00568     }
00569 
00570 _GLIBCXX_END_NAMESPACE
00571 
00572 #endif /* _SSO_STRING_BASE_H */