stl/_string_base.h

/*
 * Copyright (c) 1997-1999
 * Silicon Graphics Computer Systems, Inc.
 *
 * Copyright (c) 1999
 * Boris Fomitchev
 *
 * Copyright (c) 2003
 * Francois Dumont
 *
 * This material is provided "as is", with absolutely no warranty expressed
 * or implied. Any use is at your own risk.
 *
 * Permission to use or copy this software for any purpose is hereby granted
 * without fee, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */

#ifndef _STLP_STRING_BASE_H
#define _STLP_STRING_BASE_H

// ------------------------------------------------------------
// Class _String_base.

// _String_base is a helper class that makes it it easier to write an
// exception-safe version of basic_string.  The constructor allocates,
// but does not initialize, a block of memory.  The destructor
// deallocates, but does not destroy elements within, a block of
// memory.  The destructor assumes that _M_start either is null, or else
// points to a block of memory that was allocated using _String_base's
// allocator and whose size is _M_end_of_storage._M_data - _M_start.

_STLP_BEGIN_NAMESPACE

_STLP_MOVE_TO_PRIV_NAMESPACE

#ifndef _STLP_SHORT_STRING_SZ
#  define _STLP_SHORT_STRING_SZ 16
#endif

template <class _Tp, class _Alloc>
class _String_base {
  typedef _String_base<_Tp, _Alloc> _Self;
protected:
  _STLP_FORCE_ALLOCATORS(_Tp, _Alloc)
public:
  //dums: Some compiler(MSVC6) require it to be public not simply protected!
  enum {_DEFAULT_SIZE = _STLP_SHORT_STRING_SZ};
  //This is needed by the full move framework
  typedef typename _Alloc_traits<_Tp, _Alloc>::allocator_type allocator_type;
  typedef _STLP_alloc_proxy<_Tp*, _Tp, allocator_type> _AllocProxy;
  typedef size_t size_type;
private:
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
  union _Buffers {
    _Tp*  _M_dynamic_buf;
    _Tp   _M_static_buf[_DEFAULT_SIZE];
  } _M_buffers;
#else
  _Tp*    _M_start;
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
protected:
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
  bool _M_using_static_buf() const {
    return (_M_end_of_storage._M_data == _M_buffers._M_static_buf + _DEFAULT_SIZE);
  }
  _Tp const* _M_Start() const {
    return _M_using_static_buf()?_M_buffers._M_static_buf:_M_buffers._M_dynamic_buf;
  }
  _Tp* _M_Start() {
    return _M_using_static_buf()?_M_buffers._M_static_buf:_M_buffers._M_dynamic_buf;
  }
#else
  _Tp const* _M_Start() const {return _M_start;}
  _Tp* _M_Start() {return _M_start;}
#endif /* _STLP_USE_SHORT_STRING_OPTIM */

  _Tp*    _M_finish;
  _AllocProxy _M_end_of_storage;

  _Tp const* _M_Finish() const {return _M_finish;}
  _Tp* _M_Finish() {return _M_finish;}

  // Precondition: 0 < __n <= max_size().
  void _M_allocate_block(size_t __n = _DEFAULT_SIZE);
  void _M_deallocate_block() {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    if (!_M_using_static_buf() && (_M_buffers._M_dynamic_buf != 0))
      _M_end_of_storage.deallocate(_M_buffers._M_dynamic_buf, _M_end_of_storage._M_data - _M_buffers._M_dynamic_buf);
#else
    if (_M_start != 0)
      _M_end_of_storage.deallocate(_M_start, _M_end_of_storage._M_data - _M_start);
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
  }

  size_t max_size() const {
    const size_type __string_max_size = size_type(-1) / sizeof(_Tp);
    typename allocator_type::size_type __alloc_max_size = _M_end_of_storage.max_size();
    return (min)(__alloc_max_size, __string_max_size) - 1;
  }

  _String_base(const allocator_type& __a)
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    : _M_finish(_M_buffers._M_static_buf), _M_end_of_storage(__a, _M_buffers._M_static_buf + _DEFAULT_SIZE)
#else
    : _M_start(0), _M_finish(0), _M_end_of_storage(__a, (_Tp*)0)
#endif
    {}

  _String_base(const allocator_type& __a, size_t __n)
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    : _M_finish(_M_buffers._M_static_buf), _M_end_of_storage(__a, _M_buffers._M_static_buf + _DEFAULT_SIZE) {
#else
    : _M_start(0), _M_finish(0), _M_end_of_storage(__a, (_Tp*)0) {
#endif
      _M_allocate_block(__n);
    }

#if defined (_STLP_USE_SHORT_STRING_OPTIM)
  void _M_move_src (_Self &src) {
      if (src._M_using_static_buf()) {
        _M_buffers = src._M_buffers;
        _M_finish = _M_buffers._M_static_buf + (src._M_finish - src._M_buffers._M_static_buf);
        _M_end_of_storage._M_data = _M_buffers._M_static_buf + _DEFAULT_SIZE;
      }
      else {
        _M_buffers._M_dynamic_buf = src._M_buffers._M_dynamic_buf;
        _M_finish = src._M_finish;
        _M_end_of_storage._M_data = src._M_end_of_storage._M_data;
        src._M_buffers._M_dynamic_buf = 0;
      }
    }
#endif

  _String_base(__move_source<_Self> src)
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    : _M_end_of_storage(__move_source<_AllocProxy>(src.get()._M_end_of_storage)) {
      _M_move_src(src.get());
#else
    : _M_start(src.get()._M_start), _M_finish(src.get()._M_finish),
      _M_end_of_storage(__move_source<_AllocProxy>(src.get()._M_end_of_storage)) {
      src.get()._M_start = 0;
#endif
    }

  ~_String_base() { _M_deallocate_block(); }

  void _M_reset(_Tp *__start, _Tp *__finish, _Tp *__end_of_storage) {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    _M_buffers._M_dynamic_buf = __start;
#else
    _M_start = __start;
#endif
    _M_finish = __finish;
    _M_end_of_storage._M_data = __end_of_storage;
  }

  void _M_destroy_back () {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    if (!_M_using_static_buf())
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
      _STLP_STD::_Destroy(_M_finish);
  }

  void _M_destroy_range(size_t __from_off = 0, size_t __to_off = 1) {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    if (!_M_using_static_buf())
      _STLP_STD::_Destroy_Range(_M_buffers._M_dynamic_buf + __from_off, _M_finish + __to_off);
#else
    _STLP_STD::_Destroy_Range(_M_start + __from_off, _M_finish + __to_off);
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
  }

  void _M_destroy_ptr_range(_Tp *__f, _Tp *__l) {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    if (!_M_using_static_buf())
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
      _STLP_STD::_Destroy_Range(__f, __l);
  }

  void _M_Swap(_Self &__s) {
#if defined (_STLP_USE_SHORT_STRING_OPTIM)
    if (_M_using_static_buf()) {
      if (__s._M_using_static_buf()) {
        _STLP_STD::swap(_M_buffers, __s._M_buffers);
        _Tp *__tmp = _M_finish;
        _M_finish = _M_buffers._M_static_buf + (__s._M_finish - __s._M_buffers._M_static_buf);
        __s._M_finish = __s._M_buffers._M_static_buf + (__tmp - _M_buffers._M_static_buf);
        //We need to swap _M_end_of_storage for allocators with state:
        _M_end_of_storage.swap(__s._M_end_of_storage);
        _M_end_of_storage._M_data = _M_buffers._M_static_buf + _DEFAULT_SIZE;
        __s._M_end_of_storage._M_data = __s._M_buffers._M_static_buf + _DEFAULT_SIZE;
      } else {
        __s._M_Swap(*this);
        return;
      }
    }
    else if (__s._M_using_static_buf()) {
      _Tp *__tmp = _M_buffers._M_dynamic_buf;
      _Tp *__tmp_finish = _M_finish;
      _Tp *__tmp_end_data = _M_end_of_storage._M_data;
      _M_buffers = __s._M_buffers;
      //We need to swap _M_end_of_storage for allocators with state:
      _M_end_of_storage.swap(__s._M_end_of_storage);
      _M_end_of_storage._M_data = _M_buffers._M_static_buf + _DEFAULT_SIZE;
      _M_finish = _M_buffers._M_static_buf + (__s._M_finish - __s._M_buffers._M_static_buf);
      __s._M_buffers._M_dynamic_buf = __tmp;
      __s._M_end_of_storage._M_data = __tmp_end_data;
      __s._M_finish = __tmp_finish;
    }
    else {
      _STLP_STD::swap(_M_buffers._M_dynamic_buf, __s._M_buffers._M_dynamic_buf);
      _M_end_of_storage.swap(__s._M_end_of_storage);
      _STLP_STD::swap(_M_finish, __s._M_finish);
    }
#else
    _STLP_STD::swap(_M_start, __s._M_start);
    _M_end_of_storage.swap(__s._M_end_of_storage);
    _STLP_STD::swap(_M_finish, __s._M_finish);
#endif /* _STLP_USE_SHORT_STRING_OPTIM */
  }

  void _STLP_FUNCTION_THROWS _M_throw_length_error() const;
  void _STLP_FUNCTION_THROWS _M_throw_out_of_range() const;
};

#undef _STLP_SHORT_STRING_SZ

#if defined (_STLP_USE_TEMPLATE_EXPORT)
_STLP_EXPORT_TEMPLATE_CLASS _String_base<char, allocator<char> >;
#  if defined (_STLP_HAS_WCHAR_T)
_STLP_EXPORT_TEMPLATE_CLASS _String_base<wchar_t, allocator<wchar_t> >;
#  endif
#endif /* _STLP_USE_TEMPLATE_EXPORT */

_STLP_MOVE_TO_STD_NAMESPACE

_STLP_END_NAMESPACE

#endif /* _STLP_STRING_BASE_H */

/*
 * Local Variables:
 * mode:C++
 * End:
 */