sso_string_base.h
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// Short-string-optimized versatile string base -*- C++ -*-
// Copyright (C) 2005-2023 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file ext/sso_string_base.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{ext/vstring.h}
*/
#ifndef _SSO_STRING_BASE_H
#define _SSO_STRING_BASE_H 1
#include <bits/requires_hosted.h> // GNU extensions are currently omitted
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits, typename _Alloc>
class __sso_string_base
: protected __vstring_utility<_CharT, _Traits, _Alloc>
{
public:
typedef _Traits traits_type;
typedef typename _Traits::char_type value_type;
typedef __vstring_utility<_CharT, _Traits, _Alloc> _Util_Base;
typedef typename _Util_Base::_CharT_alloc_type _CharT_alloc_type;
typedef typename _CharT_alloc_type::size_type size_type;
private:
// Data Members:
typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
_M_dataplus;
size_type _M_string_length;
enum { _S_local_capacity = 15 };
union
{
_CharT _M_local_data[_S_local_capacity + 1];
size_type _M_allocated_capacity;
};
void
_M_data(_CharT* __p)
{ _M_dataplus._M_p = __p; }
void
_M_length(size_type __length)
{ _M_string_length = __length; }
void
_M_capacity(size_type __capacity)
{ _M_allocated_capacity = __capacity; }
bool
_M_is_local() const
{ return _M_data() == _M_local_data; }
// Create & Destroy
_CharT*
_M_create(size_type&, size_type);
void
_M_dispose()
{
if (!_M_is_local())
_M_destroy(_M_allocated_capacity);
}
void
_M_destroy(size_type __size) throw()
{ _M_get_allocator().deallocate(_M_data(), __size + 1); }
// _M_construct_aux is used to implement the 21.3.1 para 15 which
// requires special behaviour if _InIterator is an integral type
template<typename _InIterator>
void
_M_construct_aux(_InIterator __beg, _InIterator __end,
std::__false_type)
{
typedef typename std::iterator_traits<_InIterator>::iterator_category
_Tag;
_M_construct(__beg, __end, _Tag());
}
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
_M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
{ _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
void
_M_construct_aux_2(size_type __req, _CharT __c)
{ _M_construct(__req, __c); }
template<typename _InIterator>
void
_M_construct(_InIterator __beg, _InIterator __end)
{
typedef typename std::__is_integer<_InIterator>::__type _Integral;
_M_construct_aux(__beg, __end, _Integral());
}
// For Input Iterators, used in istreambuf_iterators, etc.
template<typename _InIterator>
void
_M_construct(_InIterator __beg, _InIterator __end,
std::input_iterator_tag);
// For forward_iterators up to random_access_iterators, used for
// string::iterator, _CharT*, etc.
template<typename _FwdIterator>
void
_M_construct(_FwdIterator __beg, _FwdIterator __end,
std::forward_iterator_tag);
void
_M_construct(size_type __req, _CharT __c);
public:
size_type
_M_max_size() const
{
typedef __alloc_traits<_CharT_alloc_type> _ATraits;
return (_ATraits::max_size(_M_get_allocator()) - 1) / 2;
}
_CharT*
_M_data() const
{ return _M_dataplus._M_p; }
size_type
_M_length() const
{ return _M_string_length; }
size_type
_M_capacity() const
{
return _M_is_local() ? size_type(_S_local_capacity)
: _M_allocated_capacity;
}
bool
_M_is_shared() const
{ return false; }
void
_M_set_leaked() { }
void
_M_leak() { }
void
_M_set_length(size_type __n)
{
_M_length(__n);
traits_type::assign(_M_data()[__n], _CharT());
}
__sso_string_base()
: _M_dataplus(_M_local_data)
{ _M_set_length(0); }
__sso_string_base(const _Alloc& __a);
__sso_string_base(const __sso_string_base& __rcs);
#if __cplusplus >= 201103L
__sso_string_base(__sso_string_base&& __rcs);
#endif
__sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
template<typename _InputIterator>
__sso_string_base(_InputIterator __beg, _InputIterator __end,
const _Alloc& __a);
~__sso_string_base()
{ _M_dispose(); }
_CharT_alloc_type&
_M_get_allocator()
{ return _M_dataplus; }
const _CharT_alloc_type&
_M_get_allocator() const
{ return _M_dataplus; }
void
_M_swap(__sso_string_base& __rcs);
void
_M_assign(const __sso_string_base& __rcs);
void
_M_reserve(size_type __res);
void
_M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
size_type __len2);
void
_M_erase(size_type __pos, size_type __n);
void
_M_clear()
{ _M_set_length(0); }
bool
_M_compare(const __sso_string_base&) const
{ return false; }
};
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_swap(__sso_string_base& __rcs)
{
if (this == &__rcs)
return;
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 431. Swapping containers with unequal allocators.
std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
__rcs._M_get_allocator());
if (_M_is_local())
if (__rcs._M_is_local())
{
if (_M_length() && __rcs._M_length())
{
_CharT __tmp_data[_S_local_capacity + 1];
traits_type::copy(__tmp_data, __rcs._M_local_data,
_S_local_capacity + 1);
traits_type::copy(__rcs._M_local_data, _M_local_data,
_S_local_capacity + 1);
traits_type::copy(_M_local_data, __tmp_data,
_S_local_capacity + 1);
}
else if (__rcs._M_length())
{
traits_type::copy(_M_local_data, __rcs._M_local_data,
_S_local_capacity + 1);
_M_length(__rcs._M_length());
__rcs._M_set_length(0);
return;
}
else if (_M_length())
{
traits_type::copy(__rcs._M_local_data, _M_local_data,
_S_local_capacity + 1);
__rcs._M_length(_M_length());
_M_set_length(0);
return;
}
}
else
{
const size_type __tmp_capacity = __rcs._M_allocated_capacity;
traits_type::copy(__rcs._M_local_data, _M_local_data,
_S_local_capacity + 1);
_M_data(__rcs._M_data());
__rcs._M_data(__rcs._M_local_data);
_M_capacity(__tmp_capacity);
}
else
{
const size_type __tmp_capacity = _M_allocated_capacity;
if (__rcs._M_is_local())
{
traits_type::copy(_M_local_data, __rcs._M_local_data,
_S_local_capacity + 1);
__rcs._M_data(_M_data());
_M_data(_M_local_data);
}
else
{
_CharT* __tmp_ptr = _M_data();
_M_data(__rcs._M_data());
__rcs._M_data(__tmp_ptr);
_M_capacity(__rcs._M_allocated_capacity);
}
__rcs._M_capacity(__tmp_capacity);
}
const size_type __tmp_length = _M_length();
_M_length(__rcs._M_length());
__rcs._M_length(__tmp_length);
}
template<typename _CharT, typename _Traits, typename _Alloc>
_CharT*
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_create(size_type& __capacity, size_type __old_capacity)
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 83. String::npos vs. string::max_size()
if (__capacity > _M_max_size())
std::__throw_length_error(__N("__sso_string_base::_M_create"));
// The below implements an exponential growth policy, necessary to
// meet amortized linear time requirements of the library: see
// http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
{
__capacity = 2 * __old_capacity;
// Never allocate a string bigger than max_size.
if (__capacity > _M_max_size())
__capacity = _M_max_size();
}
// NB: Need an array of char_type[__capacity], plus a terminating
// null char_type() element.
return _M_get_allocator().allocate(__capacity + 1);
}
template<typename _CharT, typename _Traits, typename _Alloc>
__sso_string_base<_CharT, _Traits, _Alloc>::
__sso_string_base(const _Alloc& __a)
: _M_dataplus(__a, _M_local_data)
{ _M_set_length(0); }
template<typename _CharT, typename _Traits, typename _Alloc>
__sso_string_base<_CharT, _Traits, _Alloc>::
__sso_string_base(const __sso_string_base& __rcs)
: _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
{ _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
#if __cplusplus >= 201103L
template<typename _CharT, typename _Traits, typename _Alloc>
__sso_string_base<_CharT, _Traits, _Alloc>::
__sso_string_base(__sso_string_base&& __rcs)
: _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
{
if (__rcs._M_is_local())
{
if (__rcs._M_length())
traits_type::copy(_M_local_data, __rcs._M_local_data,
_S_local_capacity + 1);
}
else
{
_M_data(__rcs._M_data());
_M_capacity(__rcs._M_allocated_capacity);
}
_M_set_length(__rcs._M_length());
__rcs._M_data(__rcs._M_local_data);
__rcs._M_set_length(0);
}
#endif
template<typename _CharT, typename _Traits, typename _Alloc>
__sso_string_base<_CharT, _Traits, _Alloc>::
__sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
: _M_dataplus(__a, _M_local_data)
{ _M_construct(__n, __c); }
template<typename _CharT, typename _Traits, typename _Alloc>
template<typename _InputIterator>
__sso_string_base<_CharT, _Traits, _Alloc>::
__sso_string_base(_InputIterator __beg, _InputIterator __end,
const _Alloc& __a)
: _M_dataplus(__a, _M_local_data)
{ _M_construct(__beg, __end); }
// NB: This is the special case for Input Iterators, used in
// istreambuf_iterators, etc.
// Input Iterators have a cost structure very different from
// pointers, calling for a different coding style.
template<typename _CharT, typename _Traits, typename _Alloc>
template<typename _InIterator>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_construct(_InIterator __beg, _InIterator __end,
std::input_iterator_tag)
{
size_type __len = 0;
size_type __capacity = size_type(_S_local_capacity);
while (__beg != __end && __len < __capacity)
{
_M_data()[__len++] = *__beg;
++__beg;
}
__try
{
while (__beg != __end)
{
if (__len == __capacity)
{
// Allocate more space.
__capacity = __len + 1;
_CharT* __another = _M_create(__capacity, __len);
this->_S_copy(__another, _M_data(), __len);
_M_dispose();
_M_data(__another);
_M_capacity(__capacity);
}
_M_data()[__len++] = *__beg;
++__beg;
}
}
__catch(...)
{
_M_dispose();
__throw_exception_again;
}
_M_set_length(__len);
}
template<typename _CharT, typename _Traits, typename _Alloc>
template<typename _InIterator>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_construct(_InIterator __beg, _InIterator __end,
std::forward_iterator_tag)
{
// NB: Not required, but considered best practice.
if (__is_null_pointer(__beg) && __beg != __end)
std::__throw_logic_error(__N("__sso_string_base::"
"_M_construct null not valid"));
size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
if (__dnew > size_type(_S_local_capacity))
{
_M_data(_M_create(__dnew, size_type(0)));
_M_capacity(__dnew);
}
// Check for out_of_range and length_error exceptions.
__try
{ this->_S_copy_chars(_M_data(), __beg, __end); }
__catch(...)
{
_M_dispose();
__throw_exception_again;
}
_M_set_length(__dnew);
}
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_construct(size_type __n, _CharT __c)
{
if (__n > size_type(_S_local_capacity))
{
_M_data(_M_create(__n, size_type(0)));
_M_capacity(__n);
}
if (__n)
this->_S_assign(_M_data(), __n, __c);
_M_set_length(__n);
}
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_assign(const __sso_string_base& __rcs)
{
if (this != &__rcs)
{
const size_type __rsize = __rcs._M_length();
const size_type __capacity = _M_capacity();
if (__rsize > __capacity)
{
size_type __new_capacity = __rsize;
_CharT* __tmp = _M_create(__new_capacity, __capacity);
_M_dispose();
_M_data(__tmp);
_M_capacity(__new_capacity);
}
if (__rsize)
this->_S_copy(_M_data(), __rcs._M_data(), __rsize);
_M_set_length(__rsize);
}
}
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_reserve(size_type __res)
{
// Make sure we don't shrink below the current size.
if (__res < _M_length())
__res = _M_length();
const size_type __capacity = _M_capacity();
if (__res != __capacity)
{
if (__res > __capacity
|| __res > size_type(_S_local_capacity))
{
_CharT* __tmp = _M_create(__res, __capacity);
this->_S_copy(__tmp, _M_data(), _M_length() + 1);
_M_dispose();
_M_data(__tmp);
_M_capacity(__res);
}
else if (!_M_is_local())
{
this->_S_copy(_M_local_data, _M_data(), _M_length() + 1);
_M_destroy(__capacity);
_M_data(_M_local_data);
}
}
}
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
size_type __len2)
{
const size_type __how_much = _M_length() - __pos - __len1;
size_type __new_capacity = _M_length() + __len2 - __len1;
_CharT* __r = _M_create(__new_capacity, _M_capacity());
if (__pos)
this->_S_copy(__r, _M_data(), __pos);
if (__s && __len2)
this->_S_copy(__r + __pos, __s, __len2);
if (__how_much)
this->_S_copy(__r + __pos + __len2,
_M_data() + __pos + __len1, __how_much);
_M_dispose();
_M_data(__r);
_M_capacity(__new_capacity);
}
template<typename _CharT, typename _Traits, typename _Alloc>
void
__sso_string_base<_CharT, _Traits, _Alloc>::
_M_erase(size_type __pos, size_type __n)
{
const size_type __how_much = _M_length() - __pos - __n;
if (__how_much && __n)
this->_S_move(_M_data() + __pos, _M_data() + __pos + __n, __how_much);
_M_set_length(_M_length() - __n);
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif /* _SSO_STRING_BASE_H */
requires_hosted.h
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:148
__gnu_cxx
GNU extensions for public use.
std::input_iterator_tag
Marking input iterators.
Definition stl_iterator_base_types.h:93
std::forward_iterator_tag
Forward iterators support a superset of input iterator operations.
Definition stl_iterator_base_types.h:99