path: root/libstdc++-v3/include/bits/stl_vector.h

// Vector implementation -*- C++ -*-

// Copyright (C) 2001 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 2, 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.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this  software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */

#ifndef __SGI_STL_INTERNAL_VECTOR_H
#define __SGI_STL_INTERNAL_VECTOR_H

#include <bits/stl_iterator_base_funcs.h>
#include <bits/functexcept.h>
#include <bits/concept_check.h>

namespace std
{ 

// The vector base class serves two purposes.  First, its constructor
// and destructor allocate (but don't initialize) storage.  This makes
// exception safety easier.  Second, the base class encapsulates all of
// the differences between SGI-style allocators and standard-conforming
// allocators.

// Base class for ordinary allocators.
template <class _Tp, class _Allocator, bool _IsStatic>
class _Vector_alloc_base {
public:
  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type
          allocator_type;
  allocator_type get_allocator() const { return _M_data_allocator; }

  _Vector_alloc_base(const allocator_type& __a)
    : _M_data_allocator(__a), _M_start(0), _M_finish(0), _M_end_of_storage(0) 
  {}
  
protected:
  allocator_type _M_data_allocator;
  _Tp* _M_start;
  _Tp* _M_finish;
  _Tp* _M_end_of_storage;

  _Tp* _M_allocate(size_t __n)
    { return _M_data_allocator.allocate(__n); }
  void _M_deallocate(_Tp* __p, size_t __n)
    { if (__p) _M_data_allocator.deallocate(__p, __n); }
};

// Specialization for allocators that have the property that we don't
// actually have to store an allocator object.  
template <class _Tp, class _Allocator>
class _Vector_alloc_base<_Tp, _Allocator, true> {
public:
  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type
          allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _Vector_alloc_base(const allocator_type&)
    : _M_start(0), _M_finish(0), _M_end_of_storage(0) 
  {}
  
protected:
  _Tp* _M_start;
  _Tp* _M_finish;
  _Tp* _M_end_of_storage;

  typedef typename _Alloc_traits<_Tp, _Allocator>::_Alloc_type _Alloc_type;
  _Tp* _M_allocate(size_t __n)
    { return _Alloc_type::allocate(__n); }
  void _M_deallocate(_Tp* __p, size_t __n)
    { _Alloc_type::deallocate(__p, __n);}
};

template <class _Tp, class _Alloc>
struct _Vector_base
  : public _Vector_alloc_base<_Tp, _Alloc,
                              _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
{
  typedef _Vector_alloc_base<_Tp, _Alloc, 
                             _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
          _Base;
  typedef typename _Base::allocator_type allocator_type;

  _Vector_base(const allocator_type& __a) : _Base(__a) {}
  _Vector_base(size_t __n, const allocator_type& __a) : _Base(__a) {
    _M_start = _M_allocate(__n);
    _M_finish = _M_start;
    _M_end_of_storage = _M_start + __n;
  }

  ~_Vector_base() { _M_deallocate(_M_start, _M_end_of_storage - _M_start); }
};    


template <class _Tp, class _Alloc = allocator<_Tp> >
class vector : protected _Vector_base<_Tp, _Alloc> 
{
  // concept requirements
  __glibcpp_class_requires(_Tp, _SGIAssignableConcept);

private:
  typedef _Vector_base<_Tp, _Alloc> _Base;
  typedef vector<_Tp, _Alloc> vector_type;
public:
  typedef _Tp value_type;
  typedef value_type* pointer;
  typedef const value_type* const_pointer;
  typedef __normal_iterator<pointer, vector_type> iterator;
  typedef __normal_iterator<const_pointer, vector_type> const_iterator;
  typedef value_type& reference;
  typedef const value_type& const_reference;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;

  typedef typename _Base::allocator_type allocator_type;
  allocator_type get_allocator() const { return _Base::get_allocator(); }

  typedef reverse_iterator<const_iterator> const_reverse_iterator;
  typedef reverse_iterator<iterator> reverse_iterator;

protected:
  using _Base::_M_allocate;
  using _Base::_M_deallocate;
  using _Base::_M_start;
  using _Base::_M_finish;
  using _Base::_M_end_of_storage;

protected:
  void _M_insert_aux(iterator __position, const _Tp& __x);
  void _M_insert_aux(iterator __position);

public:
  iterator begin() { return iterator (_M_start); }
  const_iterator begin() const
    { return const_iterator (_M_start); }
  iterator end() { return iterator (_M_finish); }
  const_iterator end() const { return const_iterator (_M_finish); }

  reverse_iterator rbegin()
    { return reverse_iterator(end()); }
  const_reverse_iterator rbegin() const
    { return const_reverse_iterator(end()); }
  reverse_iterator rend()
    { return reverse_iterator(begin()); }
  const_reverse_iterator rend() const
    { return const_reverse_iterator(begin()); }

  size_type size() const
    { return size_type(end() - begin()); }
  size_type max_size() const
    { return size_type(-1) / sizeof(_Tp); }
  size_type capacity() const
    { return size_type(const_iterator(_M_end_of_storage) - begin()); }
  bool empty() const
    { return begin() == end(); }

  reference operator[](size_type __n) { return *(begin() + __n); }
  const_reference operator[](size_type __n) const { return *(begin() + __n); }

  void _M_range_check(size_type __n) const {
    if (__n >= this->size())
      __throw_out_of_range("vector");
  }

  reference at(size_type __n)
    { _M_range_check(__n); return (*this)[__n]; }
  const_reference at(size_type __n) const
    { _M_range_check(__n); return (*this)[__n]; }

  explicit vector(const allocator_type& __a = allocator_type())
    : _Base(__a) {}

  vector(size_type __n, const _Tp& __value,
         const allocator_type& __a = allocator_type()) 
    : _Base(__n, __a)
    { _M_finish = uninitialized_fill_n(_M_start, __n, __value); }

  explicit vector(size_type __n)
    : _Base(__n, allocator_type())
    { _M_finish = uninitialized_fill_n(_M_start, __n, _Tp()); }

  vector(const vector<_Tp, _Alloc>& __x) 
    : _Base(__x.size(), __x.get_allocator())
    { _M_finish = uninitialized_copy(__x.begin(), __x.end(), _M_start); }

  // Check whether it's an integral type.  If so, it's not an iterator.
  template <class _InputIterator>
  vector(_InputIterator __first, _InputIterator __last,
         const allocator_type& __a = allocator_type()) : _Base(__a) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_initialize_aux(__first, __last, _Integral());
  }

  template <class _Integer>
  void _M_initialize_aux(_Integer __n, _Integer __value, __true_type) {
    _M_start = _M_allocate(__n);
    _M_end_of_storage = _M_start + __n; 
    _M_finish = uninitialized_fill_n(_M_start, __n, __value);
  }

  template <class _InputIterator>
  void _M_initialize_aux(_InputIterator __first, _InputIterator __last,
                         __false_type) {
    _M_range_initialize(__first, __last, __iterator_category(__first));
  }

  ~vector() { destroy(_M_start, _M_finish); }

  vector<_Tp, _Alloc>& operator=(const vector<_Tp, _Alloc>& __x);
  void reserve(size_type __n) {
    if (capacity() < __n) {
      const size_type __old_size = size();
      pointer __tmp = _M_allocate_and_copy(__n, _M_start, _M_finish);
      destroy(_M_start, _M_finish);
      _M_deallocate(_M_start, _M_end_of_storage - _M_start);
      _M_start = __tmp;
      _M_finish = __tmp + __old_size;
      _M_end_of_storage = _M_start + __n;
    }
  }

  // assign(), a generalized assignment member function.  Two
  // versions: one that takes a count, and one that takes a range.
  // The range version is a member template, so we dispatch on whether
  // or not the type is an integer.

  void assign(size_type __n, const _Tp& __val) { _M_fill_assign(__n, __val); }
  void _M_fill_assign(size_type __n, const _Tp& __val);

  template <class _InputIterator>
  void assign(_InputIterator __first, _InputIterator __last) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_assign_dispatch(__first, __last, _Integral());
  }

  template <class _Integer>
  void _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
    { _M_fill_assign((size_type) __n, (_Tp) __val); }

  template <class _InputIter>
  void _M_assign_dispatch(_InputIter __first, _InputIter __last, __false_type)
    { _M_assign_aux(__first, __last, __iterator_category(__first)); }

  template <class _InputIterator>
  void _M_assign_aux(_InputIterator __first, _InputIterator __last,
                     input_iterator_tag);

  template <class _ForwardIterator>
  void _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last,
                     forward_iterator_tag); 

  reference front() { return *begin(); }
  const_reference front() const { return *begin(); }
  reference back() { return *(end() - 1); }
  const_reference back() const { return *(end() - 1); }

  void push_back(const _Tp& __x) {
    if (_M_finish != _M_end_of_storage) {
      construct(_M_finish, __x);
      ++_M_finish;
    }
    else
      _M_insert_aux(end(), __x);
  }
  void push_back() {
    if (_M_finish != _M_end_of_storage) {
      construct(_M_finish);
      ++_M_finish;
    }
    else
      _M_insert_aux(end());
  }
  void swap(vector<_Tp, _Alloc>& __x) {
    std::swap(_M_start, __x._M_start);
    std::swap(_M_finish, __x._M_finish);
    std::swap(_M_end_of_storage, __x._M_end_of_storage);
  }

  iterator insert(iterator __position, const _Tp& __x) {
    size_type __n = __position - begin();
    if (_M_finish != _M_end_of_storage && __position == end()) {
      construct(_M_finish, __x);
      ++_M_finish;
    }
    else
      _M_insert_aux(iterator(__position), __x);
    return begin() + __n;
  }
  iterator insert(iterator __position) {
    size_type __n = __position - begin();
    if (_M_finish != _M_end_of_storage && __position == end()) {
      construct(_M_finish);
      ++_M_finish;
    }
    else
      _M_insert_aux(iterator(__position));
    return begin() + __n;
  }
  // Check whether it's an integral type.  If so, it's not an iterator.
  template <class _InputIterator>
  void insert(iterator __pos, _InputIterator __first, _InputIterator __last) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_insert_dispatch(__pos, __first, __last, _Integral());
  }

  template <class _Integer>
  void _M_insert_dispatch(iterator __pos, _Integer __n, _Integer __val,
                          __true_type)
    { _M_fill_insert(__pos, (size_type) __n, (_Tp) __val); }

  template <class _InputIterator>
  void _M_insert_dispatch(iterator __pos,
                          _InputIterator __first, _InputIterator __last,
                          __false_type) {
    _M_range_insert(__pos, __first, __last, __iterator_category(__first));
  }

  void insert (iterator __pos, size_type __n, const _Tp& __x)
    { _M_fill_insert(__pos, __n, __x); }

  void _M_fill_insert (iterator __pos, size_type __n, const _Tp& __x);

  void pop_back() {
    --_M_finish;
    destroy(_M_finish);
  }
  iterator erase(iterator __position) {
    if (__position + 1 != end())
      copy(__position + 1, end(), __position);
    --_M_finish;
    destroy(_M_finish);
    return __position;
  }
  iterator erase(iterator __first, iterator __last) {
    iterator __i(copy(__last, end(), __first));
    destroy(__i, end());
    _M_finish = _M_finish - (__last - __first);
    return __first;
  }

  void resize(size_type __new_size, const _Tp& __x) {
    if (__new_size < size()) 
      erase(begin() + __new_size, end());
    else
      insert(end(), __new_size - size(), __x);
  }
  void resize(size_type __new_size) { resize(__new_size, _Tp()); }
  void clear() { erase(begin(), end()); }

protected:

  template <class _ForwardIterator>
  pointer _M_allocate_and_copy(size_type __n, _ForwardIterator __first, 
                                               _ForwardIterator __last)
  {
    pointer __result = _M_allocate(__n);
    __STL_TRY {
      uninitialized_copy(__first, __last, __result);
      return __result;
    }
    __STL_UNWIND(_M_deallocate(__result, __n));
  }

  template <class _InputIterator>
  void _M_range_initialize(_InputIterator __first,  
                           _InputIterator __last, input_iterator_tag)
  {
    for ( ; __first != __last; ++__first)
      push_back(*__first);
  }

  // This function is only called by the constructor. 
  template <class _ForwardIterator>
  void _M_range_initialize(_ForwardIterator __first,
                           _ForwardIterator __last, forward_iterator_tag)
  {
    size_type __n = 0;
    distance(__first, __last, __n);
    _M_start = _M_allocate(__n);
    _M_end_of_storage = _M_start + __n;
    _M_finish = uninitialized_copy(__first, __last, _M_start);
  }

  template <class _InputIterator>
  void _M_range_insert(iterator __pos,
                       _InputIterator __first, _InputIterator __last,
                       input_iterator_tag);

  template <class _ForwardIterator>
  void _M_range_insert(iterator __pos,
                       _ForwardIterator __first, _ForwardIterator __last,
                       forward_iterator_tag);
};

template <class _Tp, class _Alloc>
inline bool 
operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{
  return __x.size() == __y.size() &&
         equal(__x.begin(), __x.end(), __y.begin());
}

template <class _Tp, class _Alloc>
inline bool 
operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{
  return lexicographical_compare(__x.begin(), __x.end(), 
                                 __y.begin(), __y.end());
}

template <class _Tp, class _Alloc>
inline void swap(vector<_Tp, _Alloc>& __x, vector<_Tp, _Alloc>& __y)
{
  __x.swap(__y);
}

template <class _Tp, class _Alloc>
inline bool
operator!=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y) {
  return !(__x == __y);
}

template <class _Tp, class _Alloc>
inline bool
operator>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y) {
  return __y < __x;
}

template <class _Tp, class _Alloc>
inline bool
operator<=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y) {
  return !(__y < __x);
}

template <class _Tp, class _Alloc>
inline bool
operator>=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y) {
  return !(__x < __y);
}

template <class _Tp, class _Alloc>
vector<_Tp,_Alloc>& 
vector<_Tp,_Alloc>::operator=(const vector<_Tp, _Alloc>& __x)
{
  if (&__x != this) {
    const size_type __xlen = __x.size();
    if (__xlen > capacity()) {
      pointer __tmp = _M_allocate_and_copy(__xlen, __x.begin(), __x.end());
      destroy(_M_start, _M_finish);
      _M_deallocate(_M_start, _M_end_of_storage - _M_start);
      _M_start = __tmp;
      _M_end_of_storage = _M_start + __xlen;
    }
    else if (size() >= __xlen) {
      iterator __i(copy(__x.begin(), __x.end(), begin()));
      destroy(__i, end());
    }
    else {
      copy(__x.begin(), __x.begin() + size(), _M_start);
      uninitialized_copy(__x.begin() + size(), __x.end(), _M_finish);
    }
    _M_finish = _M_start + __xlen;
  }
  return *this;
}

template <class _Tp, class _Alloc>
void vector<_Tp, _Alloc>::_M_fill_assign(size_t __n, const value_type& __val) 
{
  if (__n > capacity()) {
    vector<_Tp, _Alloc> __tmp(__n, __val, get_allocator());
    __tmp.swap(*this);
  }
  else if (__n > size()) {
    fill(begin(), end(), __val);
    _M_finish = uninitialized_fill_n(_M_finish, __n - size(), __val);
  }
  else
    erase(fill_n(begin(), __n, __val), end());
}

template <class _Tp, class _Alloc> template <class _InputIter>
void vector<_Tp, _Alloc>::_M_assign_aux(_InputIter __first, _InputIter __last,
                                        input_iterator_tag) {
  iterator __cur(begin());
  for ( ; __first != __last && __cur != end(); ++__cur, ++__first)
    *__cur = *__first;
  if (__first == __last)
    erase(__cur, end());
  else
    insert(end(), __first, __last);
}

template <class _Tp, class _Alloc> template <class _ForwardIter>
void
vector<_Tp, _Alloc>::_M_assign_aux(_ForwardIter __first, _ForwardIter __last,
                                   forward_iterator_tag) {
  size_type __len = 0;
  distance(__first, __last, __len);

  if (__len > capacity()) {
    pointer __tmp(_M_allocate_and_copy(__len, __first, __last));
    destroy(_M_start, _M_finish);
    _M_deallocate(_M_start, _M_end_of_storage - _M_start);
    _M_start = __tmp;
    _M_end_of_storage = _M_finish = _M_start + __len;
  }
  else if (size() >= __len) {
    iterator __new_finish(copy(__first, __last, _M_start));
    destroy(__new_finish, end());
    _M_finish = __new_finish.base();
  }
  else {
    _ForwardIter __mid = __first;
    advance(__mid, size());
    copy(__first, __mid, _M_start);
    _M_finish = uninitialized_copy(__mid, __last, _M_finish);
  }
}

template <class _Tp, class _Alloc>
void 
vector<_Tp, _Alloc>::_M_insert_aux(iterator __position, const _Tp& __x)
{
  if (_M_finish != _M_end_of_storage) {
    construct(_M_finish, *(_M_finish - 1));
    ++_M_finish;
    _Tp __x_copy = __x;
    copy_backward(__position, iterator(_M_finish - 2), iterator(_M_finish- 1));
    *__position = __x_copy;
  }
  else {
    const size_type __old_size = size();
    const size_type __len = __old_size != 0 ? 2 * __old_size : 1;
    iterator __new_start(_M_allocate(__len));
    iterator __new_finish(__new_start);
    __STL_TRY {
      __new_finish = uninitialized_copy(iterator(_M_start), __position,
                                        __new_start);
      construct(__new_finish.base(), __x);
      ++__new_finish;
      __new_finish = uninitialized_copy(__position, iterator(_M_finish),
                                        __new_finish);
    }
    __STL_UNWIND((destroy(__new_start,__new_finish), 
                  _M_deallocate(__new_start.base(),__len)));
    destroy(begin(), end());
    _M_deallocate(_M_start, _M_end_of_storage - _M_start);
    _M_start = __new_start.base();
    _M_finish = __new_finish.base();
    _M_end_of_storage = __new_start.base() + __len;
  }
}

template <class _Tp, class _Alloc>
void 
vector<_Tp, _Alloc>::_M_insert_aux(iterator __position)
{
  if (_M_finish != _M_end_of_storage) {
    construct(_M_finish, *(_M_finish - 1));
    ++_M_finish;
    copy_backward(__position, iterator(_M_finish - 2), 
		  iterator(_M_finish - 1));
    *__position = _Tp();
  }
  else {
    const size_type __old_size = size();
    const size_type __len = __old_size != 0 ? 2 * __old_size : 1;
    pointer __new_start = _M_allocate(__len);
    pointer __new_finish = __new_start;
    __STL_TRY {
      __new_finish = uninitialized_copy(iterator(_M_start), __position, 
					__new_start);
      construct(__new_finish);
      ++__new_finish;
      __new_finish = uninitialized_copy(__position, iterator(_M_finish), 
					__new_finish);
    }
    __STL_UNWIND((destroy(__new_start,__new_finish), 
                  _M_deallocate(__new_start,__len)));
    destroy(begin(), end());
    _M_deallocate(_M_start, _M_end_of_storage - _M_start);
    _M_start = __new_start;
    _M_finish = __new_finish;
    _M_end_of_storage = __new_start + __len;
  }
}

template <class _Tp, class _Alloc>
void vector<_Tp, _Alloc>::_M_fill_insert(iterator __position, size_type __n, 
                                         const _Tp& __x)
{
  if (__n != 0) {
    if (size_type(_M_end_of_storage - _M_finish) >= __n) {
      _Tp __x_copy = __x;
      const size_type __elems_after = end() - __position;
      iterator __old_finish(_M_finish);
      if (__elems_after > __n) {
        uninitialized_copy(_M_finish - __n, _M_finish, _M_finish);
        _M_finish += __n;
        copy_backward(__position, __old_finish - __n, __old_finish);
        fill(__position, __position + __n, __x_copy);
      }
      else {
        uninitialized_fill_n(_M_finish, __n - __elems_after, __x_copy);
        _M_finish += __n - __elems_after;
        uninitialized_copy(__position, __old_finish, _M_finish);
        _M_finish += __elems_after;
        fill(__position, __old_finish, __x_copy);
      }
    }
    else {
      const size_type __old_size = size();        
      const size_type __len = __old_size + max(__old_size, __n);
      iterator __new_start(_M_allocate(__len));
      iterator __new_finish(__new_start);
      __STL_TRY {
        __new_finish = uninitialized_copy(begin(), __position, __new_start);
        __new_finish = uninitialized_fill_n(__new_finish, __n, __x);
        __new_finish
          = uninitialized_copy(__position, end(), __new_finish);
      }
      __STL_UNWIND((destroy(__new_start,__new_finish), 
                    _M_deallocate(__new_start.base(),__len)));
      destroy(_M_start, _M_finish);
      _M_deallocate(_M_start, _M_end_of_storage - _M_start);
      _M_start = __new_start.base();
      _M_finish = __new_finish.base();
      _M_end_of_storage = __new_start.base() + __len;
    }
  }
}

template <class _Tp, class _Alloc> template <class _InputIterator>
void 
vector<_Tp, _Alloc>::_M_range_insert(iterator __pos, 
                                     _InputIterator __first, 
                                     _InputIterator __last,
                                     input_iterator_tag)
{
  for ( ; __first != __last; ++__first) {
    __pos = insert(__pos, *__first);
    ++__pos;
  }
}

template <class _Tp, class _Alloc> template <class _ForwardIterator>
void 
vector<_Tp, _Alloc>::_M_range_insert(iterator __position,
                                     _ForwardIterator __first,
                                     _ForwardIterator __last,
                                     forward_iterator_tag)
{
  if (__first != __last) {
    size_type __n = 0;
    distance(__first, __last, __n);
    if (size_type(_M_end_of_storage - _M_finish) >= __n) {
      const size_type __elems_after = end() - __position;
      iterator __old_finish(_M_finish);
      if (__elems_after > __n) {
        uninitialized_copy(_M_finish - __n, _M_finish, _M_finish);
        _M_finish += __n;
        copy_backward(__position, __old_finish - __n, __old_finish);
        copy(__first, __last, __position);
      }
      else {
        _ForwardIterator __mid = __first;
        advance(__mid, __elems_after);
        uninitialized_copy(__mid, __last, _M_finish);
        _M_finish += __n - __elems_after;
        uninitialized_copy(__position, __old_finish, _M_finish);
        _M_finish += __elems_after;
        copy(__first, __mid, __position);
      }
    }
    else {
      const size_type __old_size = size();
      const size_type __len = __old_size + max(__old_size, __n);
      iterator __new_start(_M_allocate(__len));
      iterator __new_finish(__new_start);
      __STL_TRY {
        __new_finish = uninitialized_copy(iterator(_M_start), 
					  __position, __new_start);
        __new_finish = uninitialized_copy(__first, __last, __new_finish);
        __new_finish
          = uninitialized_copy(__position, iterator(_M_finish), __new_finish);
      }
      __STL_UNWIND((destroy(__new_start,__new_finish), 
                    _M_deallocate(__new_start.base(),__len)));
      destroy(_M_start, _M_finish);
      _M_deallocate(_M_start, _M_end_of_storage - _M_start);
      _M_start = __new_start.base();
      _M_finish = __new_finish.base();
      _M_end_of_storage = __new_start.base() + __len;
    }
  }
}

} // namespace std 

#endif /* __SGI_STL_INTERNAL_VECTOR_H */

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