stl_bvector.h

gcc-you can use this code to learn something about gcc, and inquire further into linux,

// bit_vector and vector<bool> specialization -*- C++ -*-

// Copyright (C) 2001, 2002 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) 1996-1999
 * 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.
 */

/** @file stl_bvector.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef __GLIBCPP_INTERNAL_BVECTOR_H
#define __GLIBCPP_INTERNAL_BVECTOR_H

namespace std
{ 
  typedef unsigned long _Bit_type;
  enum { _M_word_bit = int(CHAR_BIT * sizeof(_Bit_type)) };

struct _Bit_reference {

  _Bit_type * _M_p;
  _Bit_type _M_mask;
  _Bit_reference(_Bit_type * __x, _Bit_type __y) 
    : _M_p(__x), _M_mask(__y) {}

public:
  _Bit_reference() : _M_p(0), _M_mask(0) {}
  operator bool() const { return !!(*_M_p & _M_mask); }
  _Bit_reference& operator=(bool __x)
  {
    if (__x)  *_M_p |= _M_mask;
    else      *_M_p &= ~_M_mask;
    return *this;
  }
  _Bit_reference& operator=(const _Bit_reference& __x) 
    { return *this = bool(__x); }
  bool operator==(const _Bit_reference& __x) const
    { return bool(*this) == bool(__x); }
  bool operator<(const _Bit_reference& __x) const
    { return !bool(*this) && bool(__x); }
  void flip() { *_M_p ^= _M_mask; }
};

struct _Bit_iterator_base : public iterator<random_access_iterator_tag, bool>
{
  _Bit_type * _M_p;
  unsigned int _M_offset;

  _Bit_iterator_base(_Bit_type * __x, unsigned int __y)
    : _M_p(__x), _M_offset(__y) {}

  void _M_bump_up() {
    if (_M_offset++ == _M_word_bit - 1) {
      _M_offset = 0;
      ++_M_p;
    }
  }
  void _M_bump_down() {
    if (_M_offset-- == 0) {
      _M_offset = _M_word_bit - 1;
      --_M_p;
    }
  }

  void _M_incr(ptrdiff_t __i) {
    difference_type __n = __i + _M_offset;
    _M_p += __n / _M_word_bit;
    __n = __n % _M_word_bit;
    if (__n < 0) {
      _M_offset = (unsigned int) __n + _M_word_bit;
      --_M_p;
    } else
      _M_offset = (unsigned int) __n;
  }

  bool operator==(const _Bit_iterator_base& __i) const {
    return _M_p == __i._M_p && _M_offset == __i._M_offset;
  }
  bool operator<(const _Bit_iterator_base& __i) const {
    return _M_p < __i._M_p || (_M_p == __i._M_p && _M_offset < __i._M_offset);
  }
  bool operator!=(const _Bit_iterator_base& __i) const {
    return !(*this == __i);
  }
  bool operator>(const _Bit_iterator_base& __i) const {
    return __i < *this;
  }
  bool operator<=(const _Bit_iterator_base& __i) const {
    return !(__i < *this); 
  }
  bool operator>=(const _Bit_iterator_base& __i) const {
    return !(*this < __i);
  }
};

inline ptrdiff_t
operator-(const _Bit_iterator_base& __x, const _Bit_iterator_base& __y) {
  return _M_word_bit * (__x._M_p - __y._M_p) + __x._M_offset - __y._M_offset;
}


struct _Bit_iterator : public _Bit_iterator_base
{
  typedef _Bit_reference  reference;
  typedef _Bit_reference* pointer;
  typedef _Bit_iterator   iterator;

  _Bit_iterator() : _Bit_iterator_base(0, 0) {}
  _Bit_iterator(_Bit_type * __x, unsigned int __y) 
    : _Bit_iterator_base(__x, __y) {}

  reference operator*() const { return reference(_M_p, 1UL << _M_offset); }
  iterator& operator++() {
    _M_bump_up();
    return *this;
  }
  iterator operator++(int) {
    iterator __tmp = *this;
    _M_bump_up();
    return __tmp;
  }
  iterator& operator--() {
    _M_bump_down();
    return *this;
  }
  iterator operator--(int) {
    iterator __tmp = *this;
    _M_bump_down();
    return __tmp;
  }
  iterator& operator+=(difference_type __i) {
    _M_incr(__i);
    return *this;
  }
  iterator& operator-=(difference_type __i) {
    *this += -__i;
    return *this;
  }
  iterator operator+(difference_type __i) const {
    iterator __tmp = *this;
    return __tmp += __i;
  }
  iterator operator-(difference_type __i) const {
    iterator __tmp = *this;
    return __tmp -= __i;
  }

  reference operator[](difference_type __i) { return *(*this + __i); }
};

inline _Bit_iterator 
operator+(ptrdiff_t __n, const _Bit_iterator& __x) { return __x + __n; }


struct _Bit_const_iterator : public _Bit_iterator_base
{
  typedef bool                 reference;
  typedef bool                 const_reference;
  typedef const bool*          pointer;
  typedef _Bit_const_iterator  const_iterator;

  _Bit_const_iterator() : _Bit_iterator_base(0, 0) {}
  _Bit_const_iterator(_Bit_type * __x, unsigned int __y) 
    : _Bit_iterator_base(__x, __y) {}
  _Bit_const_iterator(const _Bit_iterator& __x) 
    : _Bit_iterator_base(__x._M_p, __x._M_offset) {}

  const_reference operator*() const {
    return _Bit_reference(_M_p, 1UL << _M_offset);
  }
  const_iterator& operator++() {
    _M_bump_up();
    return *this;
  }
  const_iterator operator++(int) {
    const_iterator __tmp = *this;
    _M_bump_up();
    return __tmp;
  }
  const_iterator& operator--() {
    _M_bump_down();
    return *this;
  }
  const_iterator operator--(int) {
    const_iterator __tmp = *this;
    _M_bump_down();
    return __tmp;
  }
  const_iterator& operator+=(difference_type __i) {
    _M_incr(__i);
    return *this;
  }
  const_iterator& operator-=(difference_type __i) {
    *this += -__i;
    return *this;
  }
  const_iterator operator+(difference_type __i) const {
    const_iterator __tmp = *this;
    return __tmp += __i;
  }
  const_iterator operator-(difference_type __i) const {
    const_iterator __tmp = *this;
    return __tmp -= __i;
  }
  const_reference operator[](difference_type __i) { 
    return *(*this + __i); 
  }
};

inline _Bit_const_iterator 
operator+(ptrdiff_t __n, const _Bit_const_iterator& __x) { return __x + __n; }


// Bit-vector base class, which encapsulates the difference between
// old SGI-style allocators and standard-conforming allocators.

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

  _Bvector_alloc_base(const allocator_type& __a)
    : _M_data_allocator(__a), _M_start(), _M_finish(), _M_end_of_storage(0) {}

protected:
  _Bit_type * _M_bit_alloc(size_t __n) 
    { return _M_data_allocator.allocate((__n + _M_word_bit - 1)/_M_word_bit); }
  void _M_deallocate() {
    if (_M_start._M_p)
      _M_data_allocator.deallocate(_M_start._M_p, 
                                   _M_end_of_storage - _M_start._M_p);
  }  

  typename _Alloc_traits<_Bit_type, _Allocator>::allocator_type 
          _M_data_allocator;
  _Bit_iterator _M_start;
  _Bit_iterator _M_finish;
  _Bit_type * _M_end_of_storage;
};

// Specialization for instanceless allocators.
template <class _Allocator>
class _Bvector_alloc_base<_Allocator, true> {
public:
  typedef typename _Alloc_traits<bool, _Allocator>::allocator_type
          allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _Bvector_alloc_base(const allocator_type&)
    : _M_start(), _M_finish(), _M_end_of_storage(0) {}

protected:
  typedef typename _Alloc_traits<_Bit_type, _Allocator>::_Alloc_type
          _Alloc_type;
          
  _Bit_type * _M_bit_alloc(size_t __n) 
    { return _Alloc_type::allocate((__n + _M_word_bit - 1)/_M_word_bit); }
  void _M_deallocate() {
    if (_M_start._M_p)
      _Alloc_type::deallocate(_M_start._M_p,
                              _M_end_of_storage - _M_start._M_p);
  }  

  _Bit_iterator _M_start;
  _Bit_iterator _M_finish;
  _Bit_type * _M_end_of_storage;
};  

template <class _Alloc>
class _Bvector_base
  : public _Bvector_alloc_base<_Alloc,
                               _Alloc_traits<bool, _Alloc>::_S_instanceless>
{
  typedef _Bvector_alloc_base<_Alloc,
                              _Alloc_traits<bool, _Alloc>::_S_instanceless>
          _Base;
public:
  typedef typename _Base::allocator_type allocator_type;

  _Bvector_base(const allocator_type& __a) : _Base(__a) {}
  ~_Bvector_base() { _Base::_M_deallocate(); }
};

} // namespace std

// Declare a partial specialization of vector<T, Alloc>.
#include <bits/stl_vector.h>
namespace std
{

template <typename _Alloc> 
  class vector<bool, _Alloc> : public _Bvector_base<_Alloc> 
  {
  public:
    typedef bool value_type;
    typedef size_t size_type;
    typedef ptrdiff_t difference_type; 
    typedef _Bit_reference reference;
    typedef bool const_reference;
    typedef _Bit_reference* pointer;
    typedef const bool* const_pointer;
  
    typedef _Bit_iterator                iterator;
    typedef _Bit_const_iterator          const_iterator;
  
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
    typedef std::reverse_iterator<iterator> reverse_iterator;
  
    typedef typename _Bvector_base<_Alloc>::allocator_type allocator_type;
    allocator_type get_allocator() const {
      return _Bvector_base<_Alloc>::get_allocator();
    }