# 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 */