sso_string_base.h

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00001 // Short-string-optimized versatile string base -*- C++ -*-
00002 
00003 // Copyright (C) 2005, 2006 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 2, 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 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 /** @file ext/sso_string_base.h
00031  *  This file is a GNU extension to the Standard C++ Library.
00032  *  This is an internal header file, included by other library headers.
00033  *  You should not attempt to use it directly.
00034  */
00035 
00036 #ifndef _SSO_STRING_BASE_H
00037 #define _SSO_STRING_BASE_H 1
00038 
00039 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00040 
00041   template<typename _CharT, typename _Traits, typename _Alloc>
00042     class __sso_string_base
00043     : protected __vstring_utility<_CharT, _Traits, _Alloc>
00044     {
00045     public:
00046       typedef _Traits                       traits_type;
00047       typedef typename _Traits::char_type           value_type;
00048 
00049       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
00050       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
00051       typedef typename _CharT_alloc_type::size_type     size_type;
00052       
00053     private:
00054       // Data Members:
00055       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
00056                                                             _M_dataplus;
00057       size_type                                             _M_string_length;
00058 
00059       enum { _S_local_capacity = 15 };
00060       
00061       union
00062       {
00063     _CharT           _M_local_data[_S_local_capacity + 1];
00064     size_type        _M_allocated_capacity;
00065       };
00066 
00067       void
00068       _M_data(_CharT* __p)
00069       { _M_dataplus._M_p = __p; }
00070 
00071       void
00072       _M_length(size_type __length)
00073       { _M_string_length = __length; }
00074 
00075       void
00076       _M_capacity(size_type __capacity)
00077       { _M_allocated_capacity = __capacity; }
00078 
00079       bool
00080       _M_is_local() const
00081       { return _M_data() == _M_local_data; }
00082 
00083       // Create & Destroy
00084       _CharT*
00085       _M_create(size_type&, size_type);
00086       
00087       void
00088       _M_dispose()
00089       {
00090     if (!_M_is_local())
00091       _M_destroy(_M_allocated_capacity);
00092       }
00093 
00094       void
00095       _M_destroy(size_type __size) throw()
00096       { _M_get_allocator().deallocate(_M_data(), __size + 1); }
00097 
00098       // _M_construct_aux is used to implement the 21.3.1 para 15 which
00099       // requires special behaviour if _InIterator is an integral type
00100       template<typename _InIterator>
00101         void
00102         _M_construct_aux(_InIterator __beg, _InIterator __end, 
00103              std::__false_type)
00104     {
00105           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
00106           _M_construct(__beg, __end, _Tag());
00107     }
00108 
00109       template<typename _InIterator>
00110         void
00111         _M_construct_aux(_InIterator __beg, _InIterator __end, 
00112              std::__true_type)
00113     { _M_construct(static_cast<size_type>(__beg),
00114                static_cast<value_type>(__end)); }
00115 
00116       template<typename _InIterator>
00117         void
00118         _M_construct(_InIterator __beg, _InIterator __end)
00119     {
00120       typedef typename std::__is_integer<_InIterator>::__type _Integral;
00121       _M_construct_aux(__beg, __end, _Integral());
00122         }
00123 
00124       // For Input Iterators, used in istreambuf_iterators, etc.
00125       template<typename _InIterator>
00126         void
00127         _M_construct(_InIterator __beg, _InIterator __end,
00128              std::input_iterator_tag);
00129       
00130       // For forward_iterators up to random_access_iterators, used for
00131       // string::iterator, _CharT*, etc.
00132       template<typename _FwdIterator>
00133         void
00134         _M_construct(_FwdIterator __beg, _FwdIterator __end,
00135              std::forward_iterator_tag);
00136 
00137       void
00138       _M_construct(size_type __req, _CharT __c);
00139 
00140     public:
00141       size_type
00142       _M_max_size() const
00143       { return (_M_get_allocator().max_size() - 1) / 2; }
00144 
00145       _CharT*
00146       _M_data() const
00147       { return _M_dataplus._M_p; }
00148 
00149       size_type
00150       _M_length() const
00151       { return _M_string_length; }
00152 
00153       size_type
00154       _M_capacity() const
00155       {
00156     return _M_is_local() ? size_type(_S_local_capacity)
00157                          : _M_allocated_capacity; 
00158       }
00159 
00160       bool
00161       _M_is_shared() const
00162       { return false; }
00163 
00164       void
00165       _M_set_leaked() { }
00166 
00167       void
00168       _M_leak() { }
00169 
00170       void
00171       _M_set_length(size_type __n)
00172       {
00173     _M_length(__n);
00174     traits_type::assign(_M_data()[__n], _CharT());
00175       }
00176 
00177       __sso_string_base()
00178       : _M_dataplus(_Alloc(), _M_local_data)
00179       { _M_set_length(0); }
00180 
00181       __sso_string_base(const _Alloc& __a);
00182 
00183       __sso_string_base(const __sso_string_base& __rcs);
00184 
00185       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
00186 
00187       template<typename _InputIterator>
00188         __sso_string_base(_InputIterator __beg, _InputIterator __end,
00189               const _Alloc& __a);
00190 
00191       ~__sso_string_base()
00192       { _M_dispose(); }
00193 
00194       _CharT_alloc_type&
00195       _M_get_allocator()
00196       { return _M_dataplus; }
00197 
00198       const _CharT_alloc_type&
00199       _M_get_allocator() const
00200       { return _M_dataplus; }
00201 
00202       void
00203       _M_swap(__sso_string_base& __rcs);
00204 
00205       void
00206       _M_assign(const __sso_string_base& __rcs);
00207 
00208       void
00209       _M_reserve(size_type __res);
00210 
00211       void
00212       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00213         size_type __len2);
00214 
00215       void
00216       _M_erase(size_type __pos, size_type __n);
00217 
00218       void
00219       _M_clear()
00220       { _M_set_length(0); }
00221 
00222       bool
00223       _M_compare(const __sso_string_base&) const
00224       { return false; }
00225     };
00226 
00227   template<typename _CharT, typename _Traits, typename _Alloc>
00228     void
00229     __sso_string_base<_CharT, _Traits, _Alloc>::
00230     _M_swap(__sso_string_base& __rcs)
00231     {
00232       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00233       // 431. Swapping containers with unequal allocators.
00234       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
00235                              __rcs._M_get_allocator());
00236 
00237       if (_M_is_local())
00238     if (__rcs._M_is_local())
00239       {
00240         if (_M_length() && __rcs._M_length())
00241           {
00242         _CharT __tmp_data[_S_local_capacity + 1];
00243         traits_type::copy(__tmp_data, __rcs._M_local_data,
00244                   _S_local_capacity + 1);
00245         traits_type::copy(__rcs._M_local_data, _M_local_data,
00246                   _S_local_capacity + 1);
00247         traits_type::copy(_M_local_data, __tmp_data,
00248                   _S_local_capacity + 1);
00249           }
00250         else if (__rcs._M_length())
00251           {
00252         traits_type::copy(_M_local_data, __rcs._M_local_data,
00253                   _S_local_capacity + 1);
00254         _M_length(__rcs._M_length());
00255         __rcs._M_set_length(0);
00256         return;
00257           }
00258         else if (_M_length())
00259           {
00260         traits_type::copy(__rcs._M_local_data, _M_local_data,
00261                   _S_local_capacity + 1);
00262         __rcs._M_length(_M_length());
00263         _M_set_length(0);
00264         return;
00265           }
00266       }
00267     else
00268       {
00269         const size_type __tmp_capacity = __rcs._M_allocated_capacity;
00270         traits_type::copy(__rcs._M_local_data, _M_local_data,
00271                   _S_local_capacity + 1);
00272         _M_data(__rcs._M_data());
00273         __rcs._M_data(__rcs._M_local_data);
00274         _M_capacity(__tmp_capacity);
00275       }
00276       else
00277     {
00278       const size_type __tmp_capacity = _M_allocated_capacity;
00279       if (__rcs._M_is_local())
00280         {
00281           traits_type::copy(_M_local_data, __rcs._M_local_data,
00282                 _S_local_capacity + 1);
00283           __rcs._M_data(_M_data());
00284           _M_data(_M_local_data);
00285         }
00286       else
00287         {
00288           _CharT* __tmp_ptr = _M_data();
00289           _M_data(__rcs._M_data());
00290           __rcs._M_data(__tmp_ptr);
00291           _M_capacity(__rcs._M_allocated_capacity);
00292         }
00293       __rcs._M_capacity(__tmp_capacity);
00294     }
00295 
00296       const size_type __tmp_length = _M_length();
00297       _M_length(__rcs._M_length());
00298       __rcs._M_length(__tmp_length);
00299     }
00300 
00301   template<typename _CharT, typename _Traits, typename _Alloc>
00302     _CharT*
00303     __sso_string_base<_CharT, _Traits, _Alloc>::
00304     _M_create(size_type& __capacity, size_type __old_capacity)
00305     {
00306       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00307       // 83.  String::npos vs. string::max_size()
00308       if (__capacity > _M_max_size())
00309     std::__throw_length_error(__N("__sso_string_base::_M_create"));
00310 
00311       // The below implements an exponential growth policy, necessary to
00312       // meet amortized linear time requirements of the library: see
00313       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
00314       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
00315     {
00316       __capacity = 2 * __old_capacity;
00317       // Never allocate a string bigger than max_size.
00318       if (__capacity > _M_max_size())
00319         __capacity = _M_max_size();
00320     }
00321 
00322       // NB: Need an array of char_type[__capacity], plus a terminating
00323       // null char_type() element.
00324       return _M_get_allocator().allocate(__capacity + 1);
00325     }
00326 
00327   template<typename _CharT, typename _Traits, typename _Alloc>
00328     __sso_string_base<_CharT, _Traits, _Alloc>::
00329     __sso_string_base(const _Alloc& __a)
00330     : _M_dataplus(__a, _M_local_data)
00331     { _M_set_length(0); }
00332 
00333   template<typename _CharT, typename _Traits, typename _Alloc>
00334     __sso_string_base<_CharT, _Traits, _Alloc>::
00335     __sso_string_base(const __sso_string_base& __rcs)
00336     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
00337     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
00338 
00339   template<typename _CharT, typename _Traits, typename _Alloc>
00340     __sso_string_base<_CharT, _Traits, _Alloc>::
00341     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
00342     : _M_dataplus(__a, _M_local_data)
00343     { _M_construct(__n, __c); }
00344 
00345   template<typename _CharT, typename _Traits, typename _Alloc>
00346     template<typename _InputIterator>
00347     __sso_string_base<_CharT, _Traits, _Alloc>::
00348     __sso_string_base(_InputIterator __beg, _InputIterator __end,
00349               const _Alloc& __a)
00350     : _M_dataplus(__a, _M_local_data)
00351     { _M_construct(__beg, __end); }
00352 
00353   // NB: This is the special case for Input Iterators, used in
00354   // istreambuf_iterators, etc.
00355   // Input Iterators have a cost structure very different from
00356   // pointers, calling for a different coding style.
00357   template<typename _CharT, typename _Traits, typename _Alloc>
00358     template<typename _InIterator>
00359       void
00360       __sso_string_base<_CharT, _Traits, _Alloc>::
00361       _M_construct(_InIterator __beg, _InIterator __end,
00362            std::input_iterator_tag)
00363       {
00364     size_type __len = 0;
00365     size_type __capacity = size_type(_S_local_capacity);
00366 
00367     while (__beg != __end && __len < __capacity)
00368       {
00369         _M_data()[__len++] = *__beg;
00370         ++__beg;
00371       }
00372     
00373     try
00374       {
00375         while (__beg != __end)
00376           {
00377         if (__len == __capacity)
00378           {
00379             // Allocate more space.
00380             __capacity = __len + 1;
00381             _CharT* __another = _M_create(__capacity, __len);
00382             _S_copy(__another, _M_data(), __len);
00383             _M_dispose();
00384             _M_data(__another);
00385             _M_capacity(__capacity);
00386           }
00387         _M_data()[__len++] = *__beg;
00388         ++__beg;
00389           }
00390       }
00391     catch(...)
00392       {
00393         _M_dispose();
00394         __throw_exception_again;
00395       }
00396 
00397     _M_set_length(__len);
00398       }
00399 
00400   template<typename _CharT, typename _Traits, typename _Alloc>
00401     template<typename _InIterator>
00402       void
00403       __sso_string_base<_CharT, _Traits, _Alloc>::
00404       _M_construct(_InIterator __beg, _InIterator __end,
00405            std::forward_iterator_tag)
00406       {
00407     // NB: Not required, but considered best practice.
00408     if (__builtin_expect(_S_is_null_pointer(__beg) && __beg != __end, 0))
00409       std::__throw_logic_error(__N("__sso_string_base::"
00410                        "_M_construct NULL not valid"));
00411 
00412     size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
00413 
00414     if (__dnew > size_type(_S_local_capacity))
00415       {
00416         _M_data(_M_create(__dnew, size_type(0)));
00417         _M_capacity(__dnew);
00418       }
00419 
00420     // Check for out_of_range and length_error exceptions.
00421     try
00422       { _S_copy_chars(_M_data(), __beg, __end); }
00423     catch(...)
00424       {
00425         _M_dispose();
00426         __throw_exception_again;
00427       }
00428 
00429     _M_set_length(__dnew);
00430       }
00431 
00432   template<typename _CharT, typename _Traits, typename _Alloc>
00433     void
00434     __sso_string_base<_CharT, _Traits, _Alloc>::
00435     _M_construct(size_type __n, _CharT __c)
00436     {
00437       if (__n > size_type(_S_local_capacity))
00438     {
00439       _M_data(_M_create(__n, size_type(0)));
00440       _M_capacity(__n);
00441     }
00442 
00443       if (__n)
00444     _S_assign(_M_data(), __n, __c);
00445 
00446       _M_set_length(__n);
00447     }
00448 
00449   template<typename _CharT, typename _Traits, typename _Alloc>
00450     void
00451     __sso_string_base<_CharT, _Traits, _Alloc>::
00452     _M_assign(const __sso_string_base& __rcs)
00453     {
00454       if (this != &__rcs)
00455     {
00456       const size_type __rsize = __rcs._M_length();
00457       const size_type __capacity = _M_capacity();
00458 
00459       if (__rsize > __capacity)
00460         {
00461           size_type __new_capacity = __rsize;
00462           _CharT* __tmp = _M_create(__new_capacity, __capacity);
00463           _M_dispose();
00464           _M_data(__tmp);
00465           _M_capacity(__new_capacity);
00466         }
00467 
00468       if (__rsize)
00469         _S_copy(_M_data(), __rcs._M_data(), __rsize);
00470 
00471       _M_set_length(__rsize);
00472     }
00473     }
00474 
00475   template<typename _CharT, typename _Traits, typename _Alloc>
00476     void
00477     __sso_string_base<_CharT, _Traits, _Alloc>::
00478     _M_reserve(size_type __res)
00479     {
00480       // Make sure we don't shrink below the current size.
00481       if (__res < _M_length())
00482     __res = _M_length();
00483 
00484       const size_type __capacity = _M_capacity();
00485       if (__res != __capacity)
00486     {
00487       if (__res > __capacity
00488           || __res > size_type(_S_local_capacity))
00489         {
00490           _CharT* __tmp = _M_create(__res, __capacity);
00491           _S_copy(__tmp, _M_data(), _M_length() + 1);
00492           _M_dispose();
00493           _M_data(__tmp);
00494           _M_capacity(__res);
00495         }
00496       else if (!_M_is_local())
00497         {
00498           _S_copy(_M_local_data, _M_data(), _M_length() + 1);
00499           _M_destroy(__capacity);
00500           _M_data(_M_local_data);
00501         }
00502     }
00503     }
00504 
00505   template<typename _CharT, typename _Traits, typename _Alloc>
00506     void
00507     __sso_string_base<_CharT, _Traits, _Alloc>::
00508     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00509           const size_type __len2)
00510     {
00511       const size_type __how_much = _M_length() - __pos - __len1;
00512       
00513       size_type __new_capacity = _M_length() + __len2 - __len1;
00514       _CharT* __r = _M_create(__new_capacity, _M_capacity());
00515 
00516       if (__pos)
00517     _S_copy(__r, _M_data(), __pos);
00518       if (__s && __len2)
00519     _S_copy(__r + __pos, __s, __len2);
00520       if (__how_much)
00521     _S_copy(__r + __pos + __len2,
00522         _M_data() + __pos + __len1, __how_much);
00523       
00524       _M_dispose();
00525       _M_data(__r);
00526       _M_capacity(__new_capacity);
00527     }
00528 
00529   template<typename _CharT, typename _Traits, typename _Alloc>
00530     void
00531     __sso_string_base<_CharT, _Traits, _Alloc>::
00532     _M_erase(size_type __pos, size_type __n)
00533     {
00534       const size_type __how_much = _M_length() - __pos - __n;
00535 
00536       if (__how_much && __n)
00537     _S_move(_M_data() + __pos, _M_data() + __pos + __n,
00538         __how_much);
00539 
00540       _M_set_length(_M_length() - __n);
00541     }
00542 
00543   template<>
00544     inline bool
00545     __sso_string_base<char, std::char_traits<char>,
00546               std::allocator<char> >::
00547     _M_compare(const __sso_string_base& __rcs) const
00548     {
00549       if (this == &__rcs)
00550     return true;
00551       return false;
00552     }
00553 
00554 #ifdef _GLIBCXX_USE_WCHAR_T
00555   template<>
00556     inline bool
00557     __sso_string_base<wchar_t, std::char_traits<wchar_t>,
00558               std::allocator<wchar_t> >::
00559     _M_compare(const __sso_string_base& __rcs) const
00560     {
00561       if (this == &__rcs)
00562     return true;
00563       return false;
00564     }
00565 #endif
00566 
00567 _GLIBCXX_END_NAMESPACE
00568 
00569 #endif /* _SSO_STRING_BASE_H */

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