# __gnu_cxx::__rc_string_base< _CharT, _Traits, _Alloc > Class Template Reference

Inheritance diagram for __gnu_cxx::__rc_string_base< _CharT, _Traits, _Alloc >:

List of all members.

## Detailed Description

### template<typename _CharT, typename _Traits, typename _Alloc>
class __gnu_cxx::__rc_string_base< _CharT, _Traits, _Alloc >

Documentation? What's that? Nathan Myers <ncm@cantrip.org>.

A string looks like this:

                                            [_Rep]
                                            _M_length
       [__rc_string_base<char_type>]        _M_capacity
       _M_dataplus                          _M_refcount
       _M_p ---------------->               unnamed array of char_type

Where the _M_p points to the first character in the string, and you cast it to a pointer-to-_Rep and subtract 1 to get a pointer to the header.

This approach has the enormous advantage that a string object requires only one allocation. All the ugliness is confined within a single pair of inline functions, which each compile to a single "add" instruction: _Rep::_M_refdata(), and __rc_string_base::_M_rep(); and the allocation function which gets a block of raw bytes and with room enough and constructs a _Rep object at the front.

The reason you want _M_data pointing to the character array and not the _Rep is so that the debugger can see the string contents. (Probably we should add a non-inline member to get the _Rep for the debugger to use, so users can check the actual string length.)

Note that the _Rep object is a POD so that you can have a static "empty string" _Rep object already "constructed" before static constructors have run. The reference-count encoding is chosen so that a 0 indicates one reference, so you never try to destroy the empty-string _Rep object.

All but the last paragraph is considered pretty conventional for a C++ string implementation.

Definition at line 86 of file rc_string_base.h.

## Public Types

- typedef _Util_Base::_CharT_alloc_type _CharT_alloc_type
- typedef __vstring_utility<
  _CharT, _Traits, _Alloc > _Util_Base
- typedef _Alloc allocator_type
- typedef _CharT_alloc_type::size_type size_type
- typedef _Traits traits_type
- typedef _Traits::char_type value_type

## Public Member Functions

- template<typename _InputIterator> __rc_string_base (_InputIterator __beg, _InputIterator __end, const _Alloc &__a)
- __rc_string_base (size_type __n, _CharT __c, const _Alloc &__a)
- __rc_string_base (const __rc_string_base &__rcs)
- __rc_string_base (const _Alloc &__a)
- __rc_string_base ()
- void _M_assign (const __rc_string_base &__rcs)
- size_type _M_capacity () const
- void _M_clear ()
- template<> bool _M_compare (const __rc_string_base &__rcs) const
- template<> bool _M_compare (const __rc_string_base &__rcs) const
- bool _M_compare (const __rc_string_base &) const
- _CharT * _M_data () const
- void _M_erase (size_type __pos, size_type __n)
- const allocator_type & _M_get_allocator () const
- allocator_type & _M_get_allocator ()
- bool _M_is_shared () const
- void _M_leak ()
- size_type _M_length () const
- size_type _M_max_size () const
- void _M_mutate (size_type __pos, size_type __len1, const _CharT *__s, size_type __len2)
- void _M_reserve (size_type __res)
- void _M_set_leaked ()
- void _M_set_length (size_type __n)
- void _M_swap (__rc_string_base &__rcs)
- ~__rc_string_base ()

## Protected Types

- typedef __gnu_cxx::__normal_iterator<
  const_pointer, __gnu_cxx::__versa_string<
  _CharT, _Traits, _Alloc,
  __rc_string_base > > __const_rc_iterator
- typedef __gnu_cxx::__normal_iterator<
  const_pointer, __gnu_cxx::__versa_string<
  _CharT, _Traits, _Alloc,
  __sso_string_base > > __const_sso_iterator
- typedef __gnu_cxx::__normal_iterator<
  pointer, __gnu_cxx::__versa_string<
  _CharT, _Traits, _Alloc,
  __rc_string_base > > __rc_iterator
- typedef __gnu_cxx::__normal_iterator<
  pointer, __gnu_cxx::__versa_string<
  _CharT, _Traits, _Alloc,
  __sso_string_base > > __sso_iterator
- typedef _CharT_alloc_type::const_pointer const_pointer
- typedef _CharT_alloc_type::difference_type difference_type
- typedef _CharT_alloc_type::pointer pointer

## Static Protected Member Functions

- static void _S_assign (_CharT *__d, size_type __n, _CharT __c)
- static int _S_compare (size_type __n1, size_type __n2)
- static void _S_copy (_CharT *__d, const _CharT *__s, size_type __n)
- static void _S_copy_chars (_CharT *__p, const _CharT *__k1, const _CharT *__k2)
- static void _S_copy_chars (_CharT *__p, _CharT *__k1, _CharT *__k2)
- static void _S_copy_chars (_CharT *__p, __const_rc_iterator __k1, __const_rc_iterator __k2)
- static void _S_copy_chars (_CharT *__p, __rc_iterator __k1, __rc_iterator __k2)
- static void _S_copy_chars (_CharT *__p, __const_sso_iterator __k1, __const_sso_iterator __k2)
- static void _S_copy_chars (_CharT *__p, __sso_iterator __k1, __sso_iterator __k2)
- template<typename _Iterator> static void _S_copy_chars (_CharT *__p, _Iterator __k1, _Iterator __k2)
- static void _S_move (_CharT *__d, const _CharT *__s, size_type __n)

The documentation for this class was generated from the following file:

- rc_string_base.h