basic_string.tcc

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

			   typename iterator_traits<const _CharT*>::iterator_category());
     }
  
  template<typename _CharT, typename _Traits, typename _Alloc>
    void
    basic_string<_CharT, _Traits, _Alloc>::_Rep::
    _M_destroy(const _Alloc& __a) throw ()
    {
      size_type __size = sizeof(_Rep) + (_M_capacity + 1) * sizeof(_CharT);
      _Raw_bytes_alloc(__a).deallocate(reinterpret_cast<char*>(this), __size);
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    void
    basic_string<_CharT, _Traits, _Alloc>::_M_leak_hard()
    {
      if (_M_rep()->_M_is_shared()) 
	_M_mutate(0, 0, 0);
      _M_rep()->_M_set_leaked();
    }

  // _M_mutate and, below, _M_clone, include, in the same form, 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.
  // The policy is active for allocations requiring an amount of memory above
  // system pagesize. This is consistent with the requirements of the standard:
  // see, f.i., http://gcc.gnu.org/ml/libstdc++/2001-07/msg00130.html
  template<typename _CharT, typename _Traits, typename _Alloc>
    void
    basic_string<_CharT, _Traits, _Alloc>::
    _M_mutate(size_type __pos, size_type __len1, size_type __len2)
    {
      size_type       __old_size = this->size();
      const size_type __new_size = __old_size + __len2 - __len1;
      const _CharT*        __src = _M_data()  + __pos + __len1;
      const size_type __how_much = __old_size - __pos - __len1;
      
      if (_M_rep()->_M_is_shared() || __new_size > capacity())
	{
	  // Must reallocate.
	  allocator_type __a = get_allocator();
	  // See below (_S_create) for the meaning and value of these
	  // constants.
	  const size_type __pagesize = 4096;
	  const size_type __malloc_header_size = 4 * sizeof (void*);
	  // The biggest string which fits in a memory page
	  const size_type __page_capacity = (__pagesize - __malloc_header_size
					     - sizeof(_Rep) - sizeof(_CharT)) 
	    				     / sizeof(_CharT);
	  _Rep* __r;
	  if (__new_size > capacity() && __new_size > __page_capacity)
	    // Growing exponentially.
	    __r = _Rep::_S_create(__new_size > 2*capacity() ?
				  __new_size : 2*capacity(), __a);
	  else
	    __r = _Rep::_S_create(__new_size, __a);
	  try 
	    {
	      if (__pos)
		traits_type::copy(__r->_M_refdata(), _M_data(), __pos);
	      if (__how_much)
		traits_type::copy(__r->_M_refdata() + __pos + __len2, 
				  __src, __how_much);
	    }
	  catch(...) 
	    { 
	      __r->_M_dispose(get_allocator()); 
	      __throw_exception_again;
	    }
	  _M_rep()->_M_dispose(__a);
	  _M_data(__r->_M_refdata());
      }
      else if (__how_much && __len1 != __len2)
	{
	  // Work in-place
	  traits_type::move(_M_data() + __pos + __len2, __src, __how_much);
	}
      _M_rep()->_M_set_sharable();
      _M_rep()->_M_length = __new_size;
      _M_data()[__new_size] = _Rep::_S_terminal; // grrr. (per 21.3.4)
    // You cannot leave those LWG people alone for a second.
    }
  
  template<typename _CharT, typename _Traits, typename _Alloc>
    void
    basic_string<_CharT, _Traits, _Alloc>::reserve(size_type __res)
    {
      if (__res > this->capacity() || _M_rep()->_M_is_shared())
        {
	  if (__res > this->max_size())
	    __throw_length_error("basic_string::reserve");
	  // Make sure we don't shrink below the current size
	  if (__res < this->size())
	    __res = this->size();
	  allocator_type __a = get_allocator();
	  _CharT* __tmp = _M_rep()->_M_clone(__a, __res - this->size());
	  _M_rep()->_M_dispose(__a);
	  _M_data(__tmp);
        }
    }
  
  template<typename _CharT, typename _Traits, typename _Alloc>
    void basic_string<_CharT, _Traits, _Alloc>::swap(basic_string& __s)
    {
      if (_M_rep()->_M_is_leaked()) 
	_M_rep()->_M_set_sharable();
      if (__s._M_rep()->_M_is_leaked()) 
	__s._M_rep()->_M_set_sharable();
      if (this->get_allocator() == __s.get_allocator())
	{
	  _CharT* __tmp = _M_data();
	  _M_data(__s._M_data());
	  __s._M_data(__tmp);
	}
      // The code below can usually be optimized away.
      else 
	{
	  basic_string __tmp1(_M_ibegin(), _M_iend(), __s.get_allocator());
	  basic_string __tmp2(__s._M_ibegin(), __s._M_iend(), 
			      this->get_allocator());
	  *this = __tmp2;
	  __s = __tmp1;
	}
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    typename basic_string<_CharT, _Traits, _Alloc>::_Rep*
    basic_string<_CharT, _Traits, _Alloc>::_Rep::
    _S_create(size_t __capacity, const _Alloc& __alloc)
    {
      typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
      // 83.  String::npos vs. string::max_size()
      if (__capacity > _S_max_size)
#else
      if (__capacity == npos)
#endif
	__throw_length_error("basic_string::_S_create");

      // NB: Need an array of char_type[__capacity], plus a
      // terminating null char_type() element, plus enough for the
      // _Rep data structure. Whew. Seemingly so needy, yet so elemental.
      size_t __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);

      // The standard places no restriction on allocating more memory
      // than is strictly needed within this layer at the moment or as
      // requested by an explicit application call to reserve().  Many
      // malloc implementations perform quite poorly when an
      // application attempts to allocate memory in a stepwise fashion
      // growing each allocation size by only 1 char.  Additionally,
      // it makes little sense to allocate less linear memory than the
      // natural blocking size of the malloc implementation.
      // Unfortunately, we would need a somewhat low-level calculation
      // with tuned parameters to get this perfect for any particular
      // malloc implementation.  Fortunately, generalizations about
      // common features seen among implementations seems to suffice.

      // __pagesize need not match the actual VM page size for good
      // results in practice, thus we pick a common value on the low
      // side.  __malloc_header_size is an estimate of the amount of
      // overhead per memory allocation (in practice seen N * sizeof
      // (void*) where N is 0, 2 or 4).  According to folklore,
      // picking this value on the high side is better than
      // low-balling it (especially when this algorithm is used with
      // malloc implementations that allocate memory blocks rounded up
      // to a size which is a power of 2).
      const size_t __pagesize = 4096; // must be 2^i * __subpagesize
      const size_t __subpagesize = 128; // should be >> __malloc_header_size
      const size_t __malloc_header_size = 4 * sizeof (void*);
      if ((__size + __malloc_header_size) > __pagesize)
	{
	  size_t __extra =
	    (__pagesize - ((__size + __malloc_header_size) % __pagesize))
	    % __pagesize;
	  __capacity += __extra / sizeof(_CharT);
	  __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
	}
      else if (__size > __subpagesize)
	{
	  size_t __extra =
	    (__subpagesize - ((__size + __malloc_header_size) % __subpagesize))
	    % __subpagesize;
	  __capacity += __extra / sizeof(_CharT);
	  __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
	}

      // NB: Might throw, but no worries about a leak, mate: _Rep()
      // does not throw.
      void* __place = _Raw_bytes_alloc(__alloc).allocate(__size);
      _Rep *__p = new (__place) _Rep;
      __p->_M_capacity = __capacity;
      __p->_M_set_sharable();  // One reference.
      __p->_M_length = 0;
      return __p;
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    _CharT*
    basic_string<_CharT, _Traits, _Alloc>::_Rep::
    _M_clone(const _Alloc& __alloc, size_type __res)
    {
      // Requested capacity of the clone.
      const size_type __requested_cap = _M_length + __res;
      // See above (_S_create) for the meaning and value of these constants.
      const size_type __pagesize = 4096;
      const size_type __malloc_header_size = 4 * sizeof (void*);
      // The biggest string which fits in a memory page.
      const size_type __page_capacity =
        (__pagesize - __malloc_header_size - sizeof(_Rep) - sizeof(_CharT))
        / sizeof(_CharT);
      _Rep* __r;
      if (__requested_cap > _M_capacity && __requested_cap > __page_capacity)
        // Growing exponentially.
        __r = _Rep::_S_create(__requested_cap > 2*_M_capacity ?
                              __requested_cap : 2*_M_capacity, __alloc);
      else
        __r = _Rep::_S_create(__requested_cap, __alloc);
      
      if (_M_length)
	{
	  try 
	    { traits_type::copy(__r->_M_refdata(), _M_refdata(), _M_length); }
	  catch(...)  
	    { 
	      __r->_M_destroy(__alloc); 
	      __throw_exception_again;
	    }
	}
      __r->_M_length = _M_length;
      __r->_M_refdata()[_M_length] = _Rep::_S_terminal;
      return __r->_M_refdata();
    }
  
  template<typename _CharT, typename _Traits, typename _Alloc>
    void
    basic_string<_CharT, _Traits, _Alloc>::resize(size_type __n, _CharT __c)
    {
      if (__n > max_size())
	__throw_length_error("basic_string::resize");
      size_type __size = this->size();
      if (__size < __n)
	this->append(__n - __size, __c);
      else if (__n < __size)
	this->erase(__n);
      // else nothing (in particular, avoid calling _M_mutate() unnecessarily.)
    }

  // This is the general replace helper, which currently gets instantiated both
  // for input iterators and reverse iterators. It buffers internally and then
  // calls _M_replace_safe.
  template<typename _CharT, typename _Traits, typename _Alloc>
    template<typename _InputIter>
      basic_string<_CharT, _Traits, _Alloc>&
      basic_string<_CharT, _Traits, _Alloc>::
      _M_replace(iterator __i1, iterator __i2, _InputIter __k1, 
		 _InputIter __k2, input_iterator_tag)
      {
	// Save concerned source string data in a temporary.
	basic_string __s(__k1, __k2);
	return _M_replace_safe(__i1, __i2, __s._M_ibegin(), __s._M_iend());
      }

  // This is a special replace helper, which does not buffer internally
  // and can be used in "safe" situations involving forward iterators,
  // i.e., when source and destination ranges are known to not overlap.
  template<typename _CharT, typename _Traits, typename _Alloc>
    template<typename _ForwardIter>
      basic_string<_CharT, _Traits, _Alloc>&
      basic_string<_CharT, _Traits, _Alloc>::
      _M_replace_safe(iterator __i1, iterator __i2, _ForwardIter __k1, 
		      _ForwardIter __k2)
      {
	size_type __dnew = static_cast<size_type>(std::distance(__k1, __k2));
	size_type __dold = __i2 - __i1;
	size_type __dmax = this->max_size();

	if (__dmax <= __dnew)
	  __throw_length_error("basic_string::_M_replace");
	size_type __off = __i1 - _M_ibegin();
	_M_mutate(__off, __dold, __dnew);

	// Invalidated __i1, __i2
        if (__dnew)
	  _S_copy_chars(_M_data() + __off, __k1, __k2);

	return *this;
      }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>&
    basic_string<_CharT, _Traits, _Alloc>::
    replace(size_type __pos1, size_type __n1, const basic_string& __str,
	    size_type __pos2, size_type __n2)
    {
      const size_type __strsize = __str.size();
      if (__pos2 > __strsize)
	__throw_out_of_range("basic_string::replace");
      const bool __testn2 = __n2 < __strsize - __pos2;
      const size_type __foldn2 = __testn2 ? __n2 : __strsize - __pos2;
      return this->replace(__pos1, __n1,
			   __str._M_data() + __pos2, __foldn2);      
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>&
    basic_string<_CharT, _Traits, _Alloc>::
    append(const basic_string& __str)
    {
      // Iff appending itself, string needs to pre-reserve the
      // correct size so that _M_mutate does not clobber the
      // iterators formed here.
      size_type __size = __str.size();
      size_type __len = __size + this->size();
      if (__len > this->capacity())
	this->reserve(__len);
      return _M_replace_safe(_M_iend(), _M_iend(), __str._M_ibegin(),
			     __str._M_iend());
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>&
    basic_string<_CharT, _Traits, _Alloc>::
    append(const basic_string& __str, size_type __pos, size_type __n)
    {
      // Iff appending itself, string needs to pre-reserve the
      // correct size so that _M_mutate does not clobber the
      // iterators formed here.
      size_type __len = std::min(size_type(__str.size() - __pos),
				 __n) + this->size();
      if (__len > this->capacity())
	this->reserve(__len);
      return _M_replace_safe(_M_iend(), _M_iend(), __str._M_check(__pos),
			     __str._M_fold(__pos, __n));
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>&
    basic_string<_CharT, _Traits, _Alloc>::
    append(const _CharT* __s, size_type __n)
    {
      size_type __len = __n + this->size();
      if (__len > this->capacity())
	this->reserve(__len);
      return _M_replace_safe(_M_iend(), _M_iend(), __s, __s + __n);
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>&
    basic_string<_CharT, _Traits, _Alloc>::
    append(size_type __n, _CharT __c)
    {
      size_type __len = __n + this->size();
      if (__len > this->capacity())
	this->reserve(__len);
       return this->replace(_M_iend(), _M_iend(), __n, __c);
    }

  template<typename _CharT, typename _Traits, typename _Alloc>
    basic_string<_CharT, _Traits, _Alloc>
    operator+(const _CharT* __lhs,
	      const basic_string<_CharT, _Traits, _Alloc>& __rhs)
    {
      typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
      typedef typename __string_type::size_type	  __size_type;
      __size_type __len = _Traits::length(__lhs);