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

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