sso_string_base.h

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00001 // Short-string-optimized versatile string base -*- C++ -*-
00002 
00003 // Copyright (C) 2005, 2006, 2007 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       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00110       // 438. Ambiguity in the "do the right thing" clause
00111       template<typename _Integer>
00112         void
00113         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
00114     { _M_construct(static_cast<size_type>(__beg), __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(_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 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00186       __sso_string_base(__sso_string_base&& __rcs);
00187 #endif
00188 
00189       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
00190 
00191       template<typename _InputIterator>
00192         __sso_string_base(_InputIterator __beg, _InputIterator __end,
00193               const _Alloc& __a);
00194 
00195       ~__sso_string_base()
00196       { _M_dispose(); }
00197 
00198       _CharT_alloc_type&
00199       _M_get_allocator()
00200       { return _M_dataplus; }
00201 
00202       const _CharT_alloc_type&
00203       _M_get_allocator() const
00204       { return _M_dataplus; }
00205 
00206       void
00207       _M_swap(__sso_string_base& __rcs);
00208 
00209       void
00210       _M_assign(const __sso_string_base& __rcs);
00211 
00212       void
00213       _M_reserve(size_type __res);
00214 
00215       void
00216       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00217         size_type __len2);
00218 
00219       void
00220       _M_erase(size_type __pos, size_type __n);
00221 
00222       void
00223       _M_clear()
00224       { _M_set_length(0); }
00225 
00226       bool
00227       _M_compare(const __sso_string_base&) const
00228       { return false; }
00229     };
00230 
00231   template<typename _CharT, typename _Traits, typename _Alloc>
00232     void
00233     __sso_string_base<_CharT, _Traits, _Alloc>::
00234     _M_swap(__sso_string_base& __rcs)
00235     {
00236       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00237       // 431. Swapping containers with unequal allocators.
00238       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
00239                              __rcs._M_get_allocator());
00240 
00241       if (_M_is_local())
00242     if (__rcs._M_is_local())
00243       {
00244         if (_M_length() && __rcs._M_length())
00245           {
00246         _CharT __tmp_data[_S_local_capacity + 1];
00247         traits_type::copy(__tmp_data, __rcs._M_local_data,
00248                   _S_local_capacity + 1);
00249         traits_type::copy(__rcs._M_local_data, _M_local_data,
00250                   _S_local_capacity + 1);
00251         traits_type::copy(_M_local_data, __tmp_data,
00252                   _S_local_capacity + 1);
00253           }
00254         else if (__rcs._M_length())
00255           {
00256         traits_type::copy(_M_local_data, __rcs._M_local_data,
00257                   _S_local_capacity + 1);
00258         _M_length(__rcs._M_length());
00259         __rcs._M_set_length(0);
00260         return;
00261           }
00262         else if (_M_length())
00263           {
00264         traits_type::copy(__rcs._M_local_data, _M_local_data,
00265                   _S_local_capacity + 1);
00266         __rcs._M_length(_M_length());
00267         _M_set_length(0);
00268         return;
00269           }
00270       }
00271     else
00272       {
00273         const size_type __tmp_capacity = __rcs._M_allocated_capacity;
00274         traits_type::copy(__rcs._M_local_data, _M_local_data,
00275                   _S_local_capacity + 1);
00276         _M_data(__rcs._M_data());
00277         __rcs._M_data(__rcs._M_local_data);
00278         _M_capacity(__tmp_capacity);
00279       }
00280       else
00281     {
00282       const size_type __tmp_capacity = _M_allocated_capacity;
00283       if (__rcs._M_is_local())
00284         {
00285           traits_type::copy(_M_local_data, __rcs._M_local_data,
00286                 _S_local_capacity + 1);
00287           __rcs._M_data(_M_data());
00288           _M_data(_M_local_data);
00289         }
00290       else
00291         {
00292           _CharT* __tmp_ptr = _M_data();
00293           _M_data(__rcs._M_data());
00294           __rcs._M_data(__tmp_ptr);
00295           _M_capacity(__rcs._M_allocated_capacity);
00296         }
00297       __rcs._M_capacity(__tmp_capacity);
00298     }
00299 
00300       const size_type __tmp_length = _M_length();
00301       _M_length(__rcs._M_length());
00302       __rcs._M_length(__tmp_length);
00303     }
00304 
00305   template<typename _CharT, typename _Traits, typename _Alloc>
00306     _CharT*
00307     __sso_string_base<_CharT, _Traits, _Alloc>::
00308     _M_create(size_type& __capacity, size_type __old_capacity)
00309     {
00310       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00311       // 83.  String::npos vs. string::max_size()
00312       if (__capacity > _M_max_size())
00313     std::__throw_length_error(__N("__sso_string_base::_M_create"));
00314 
00315       // The below implements an exponential growth policy, necessary to
00316       // meet amortized linear time requirements of the library: see
00317       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
00318       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
00319     {
00320       __capacity = 2 * __old_capacity;
00321       // Never allocate a string bigger than max_size.
00322       if (__capacity > _M_max_size())
00323         __capacity = _M_max_size();
00324     }
00325 
00326       // NB: Need an array of char_type[__capacity], plus a terminating
00327       // null char_type() element.
00328       return _M_get_allocator().allocate(__capacity + 1);
00329     }
00330 
00331   template<typename _CharT, typename _Traits, typename _Alloc>
00332     __sso_string_base<_CharT, _Traits, _Alloc>::
00333     __sso_string_base(const _Alloc& __a)
00334     : _M_dataplus(__a, _M_local_data)
00335     { _M_set_length(0); }
00336 
00337   template<typename _CharT, typename _Traits, typename _Alloc>
00338     __sso_string_base<_CharT, _Traits, _Alloc>::
00339     __sso_string_base(const __sso_string_base& __rcs)
00340     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
00341     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
00342 
00343 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00344   template<typename _CharT, typename _Traits, typename _Alloc>
00345     __sso_string_base<_CharT, _Traits, _Alloc>::
00346     __sso_string_base(__sso_string_base&& __rcs)
00347     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
00348     {
00349       if (__rcs._M_is_local())
00350     {
00351       if (__rcs._M_length())
00352         traits_type::copy(_M_local_data, __rcs._M_local_data,
00353                   _S_local_capacity + 1);
00354     }
00355       else
00356     {
00357       _M_data(__rcs._M_data());
00358       _M_capacity(__rcs._M_allocated_capacity);
00359     }
00360 
00361       _M_length(__rcs._M_length());
00362       __rcs._M_length(0);
00363       __rcs._M_data(__rcs._M_local_data);
00364     }
00365 #endif
00366 
00367   template<typename _CharT, typename _Traits, typename _Alloc>
00368     __sso_string_base<_CharT, _Traits, _Alloc>::
00369     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
00370     : _M_dataplus(__a, _M_local_data)
00371     { _M_construct(__n, __c); }
00372 
00373   template<typename _CharT, typename _Traits, typename _Alloc>
00374     template<typename _InputIterator>
00375     __sso_string_base<_CharT, _Traits, _Alloc>::
00376     __sso_string_base(_InputIterator __beg, _InputIterator __end,
00377               const _Alloc& __a)
00378     : _M_dataplus(__a, _M_local_data)
00379     { _M_construct(__beg, __end); }
00380 
00381   // NB: This is the special case for Input Iterators, used in
00382   // istreambuf_iterators, etc.
00383   // Input Iterators have a cost structure very different from
00384   // pointers, calling for a different coding style.
00385   template<typename _CharT, typename _Traits, typename _Alloc>
00386     template<typename _InIterator>
00387       void
00388       __sso_string_base<_CharT, _Traits, _Alloc>::
00389       _M_construct(_InIterator __beg, _InIterator __end,
00390            std::input_iterator_tag)
00391       {
00392     size_type __len = 0;
00393     size_type __capacity = size_type(_S_local_capacity);
00394 
00395     while (__beg != __end && __len < __capacity)
00396       {
00397         _M_data()[__len++] = *__beg;
00398         ++__beg;
00399       }
00400     
00401     try
00402       {
00403         while (__beg != __end)
00404           {
00405         if (__len == __capacity)
00406           {
00407             // Allocate more space.
00408             __capacity = __len + 1;
00409             _CharT* __another = _M_create(__capacity, __len);
00410             _S_copy(__another, _M_data(), __len);
00411             _M_dispose();
00412             _M_data(__another);
00413             _M_capacity(__capacity);
00414           }
00415         _M_data()[__len++] = *__beg;
00416         ++__beg;
00417           }
00418       }
00419     catch(...)
00420       {
00421         _M_dispose();
00422         __throw_exception_again;
00423       }
00424 
00425     _M_set_length(__len);
00426       }
00427 
00428   template<typename _CharT, typename _Traits, typename _Alloc>
00429     template<typename _InIterator>
00430       void
00431       __sso_string_base<_CharT, _Traits, _Alloc>::
00432       _M_construct(_InIterator __beg, _InIterator __end,
00433            std::forward_iterator_tag)
00434       {
00435     // NB: Not required, but considered best practice.
00436     if (__builtin_expect(__is_null_pointer(__beg) && __beg != __end, 0))
00437       std::__throw_logic_error(__N("__sso_string_base::"
00438                        "_M_construct NULL not valid"));
00439 
00440     size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
00441 
00442     if (__dnew > size_type(_S_local_capacity))
00443       {
00444         _M_data(_M_create(__dnew, size_type(0)));
00445         _M_capacity(__dnew);
00446       }
00447 
00448     // Check for out_of_range and length_error exceptions.
00449     try
00450       { _S_copy_chars(_M_data(), __beg, __end); }
00451     catch(...)
00452       {
00453         _M_dispose();
00454         __throw_exception_again;
00455       }
00456 
00457     _M_set_length(__dnew);
00458       }
00459 
00460   template<typename _CharT, typename _Traits, typename _Alloc>
00461     void
00462     __sso_string_base<_CharT, _Traits, _Alloc>::
00463     _M_construct(size_type __n, _CharT __c)
00464     {
00465       if (__n > size_type(_S_local_capacity))
00466     {
00467       _M_data(_M_create(__n, size_type(0)));
00468       _M_capacity(__n);
00469     }
00470 
00471       if (__n)
00472     _S_assign(_M_data(), __n, __c);
00473 
00474       _M_set_length(__n);
00475     }
00476 
00477   template<typename _CharT, typename _Traits, typename _Alloc>
00478     void
00479     __sso_string_base<_CharT, _Traits, _Alloc>::
00480     _M_assign(const __sso_string_base& __rcs)
00481     {
00482       if (this != &__rcs)
00483     {
00484       const size_type __rsize = __rcs._M_length();
00485       const size_type __capacity = _M_capacity();
00486 
00487       if (__rsize > __capacity)
00488         {
00489           size_type __new_capacity = __rsize;
00490           _CharT* __tmp = _M_create(__new_capacity, __capacity);
00491           _M_dispose();
00492           _M_data(__tmp);
00493           _M_capacity(__new_capacity);
00494         }
00495 
00496       if (__rsize)
00497         _S_copy(_M_data(), __rcs._M_data(), __rsize);
00498 
00499       _M_set_length(__rsize);
00500     }
00501     }
00502 
00503   template<typename _CharT, typename _Traits, typename _Alloc>
00504     void
00505     __sso_string_base<_CharT, _Traits, _Alloc>::
00506     _M_reserve(size_type __res)
00507     {
00508       // Make sure we don't shrink below the current size.
00509       if (__res < _M_length())
00510     __res = _M_length();
00511 
00512       const size_type __capacity = _M_capacity();
00513       if (__res != __capacity)
00514     {
00515       if (__res > __capacity
00516           || __res > size_type(_S_local_capacity))
00517         {
00518           _CharT* __tmp = _M_create(__res, __capacity);
00519           _S_copy(__tmp, _M_data(), _M_length() + 1);
00520           _M_dispose();
00521           _M_data(__tmp);
00522           _M_capacity(__res);
00523         }
00524       else if (!_M_is_local())
00525         {
00526           _S_copy(_M_local_data, _M_data(), _M_length() + 1);
00527           _M_destroy(__capacity);
00528           _M_data(_M_local_data);
00529         }
00530     }
00531     }
00532 
00533   template<typename _CharT, typename _Traits, typename _Alloc>
00534     void
00535     __sso_string_base<_CharT, _Traits, _Alloc>::
00536     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
00537           const size_type __len2)
00538     {
00539       const size_type __how_much = _M_length() - __pos - __len1;
00540       
00541       size_type __new_capacity = _M_length() + __len2 - __len1;
00542       _CharT* __r = _M_create(__new_capacity, _M_capacity());
00543 
00544       if (__pos)
00545     _S_copy(__r, _M_data(), __pos);
00546       if (__s && __len2)
00547     _S_copy(__r + __pos, __s, __len2);
00548       if (__how_much)
00549     _S_copy(__r + __pos + __len2,
00550         _M_data() + __pos + __len1, __how_much);
00551       
00552       _M_dispose();
00553       _M_data(__r);
00554       _M_capacity(__new_capacity);
00555     }
00556 
00557   template<typename _CharT, typename _Traits, typename _Alloc>
00558     void
00559     __sso_string_base<_CharT, _Traits, _Alloc>::
00560     _M_erase(size_type __pos, size_type __n)
00561     {
00562       const size_type __how_much = _M_length() - __pos - __n;
00563 
00564       if (__how_much && __n)
00565     _S_move(_M_data() + __pos, _M_data() + __pos + __n,
00566         __how_much);
00567 
00568       _M_set_length(_M_length() - __n);
00569     }
00570 
00571 _GLIBCXX_END_NAMESPACE
00572 
00573 #endif /* _SSO_STRING_BASE_H */

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