bitset

c++ STL source code, hash and vector etc

/*
 * Copyright (c) 1998
 * 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.
 */ 

#ifndef __SGI_STL_BITSET
#define __SGI_STL_BITSET

// A bitset of size N has N % (sizeof(unsigned long) * CHAR_BIT) unused 
// bits.  (They are the high- order bits in the highest word.)  It is
// a class invariant of class bitset<> that those unused bits are
// always zero.

// Most of the actual code isn't contained in bitset<> itself, but in the 
// base class _Base_bitset.  The base class works with whole words, not with
// individual bits.  This allows us to specialize _Base_bitset for the
// important special case where the bitset is only a single word.

// The C++ standard does not define the precise semantics of operator[].
// In this implementation the const version of operator[] is equivalent
// to test(), except that it does no range checking.  The non-const version
// returns a reference to a bit, again without doing any range checking.


#include <stddef.h>     // for size_t
#include <string.h>     // for memset
#include <string>
#include <stdexcept>    // for invalid_argument, out_of_range, overflow_error

#ifdef __STL_USE_NEW_IOSTREAMS 
#include <iostream>
#else
#include <iostream.h>   // for istream, ostream
#endif

#define __BITS_PER_WORD (CHAR_BIT*sizeof(unsigned long))
#define __BITSET_WORDS(__n) \
 ((__n) < 1 ? 1 : ((__n) + __BITS_PER_WORD - 1)/__BITS_PER_WORD)

__STL_BEGIN_NAMESPACE

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1209
#endif

// structure to aid in counting bits
template<bool __dummy> 
struct _Bit_count {
  static unsigned char _S_bit_count[256];
};

// Mapping from 8 bit unsigned integers to the index of the first one
// bit:
template<bool __dummy> 
struct _First_one {
  static unsigned char _S_first_one[256];
};

//
// Base class: general case.
//

template<size_t _Nw>
struct _Base_bitset {
  typedef unsigned long _WordT;

  _WordT _M_w[_Nw];                // 0 is the least significant word.

  _Base_bitset( void ) { _M_do_reset(); }
  _Base_bitset(unsigned long __val) {
    _M_do_reset();
    _M_w[0] = __val;
  }

  static size_t _S_whichword( size_t __pos )
    { return __pos / __BITS_PER_WORD; }
  static size_t _S_whichbyte( size_t __pos )
    { return (__pos % __BITS_PER_WORD) / CHAR_BIT; }
  static size_t _S_whichbit( size_t __pos )
    { return __pos % __BITS_PER_WORD; }
  static _WordT _S_maskbit( size_t __pos )
    { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

  _WordT& _M_getword(size_t __pos)       { return _M_w[_S_whichword(__pos)]; }
  _WordT  _M_getword(size_t __pos) const { return _M_w[_S_whichword(__pos)]; }

  _WordT& _M_hiword()       { return _M_w[_Nw - 1]; }
  _WordT  _M_hiword() const { return _M_w[_Nw - 1]; }

  void _M_do_and(const _Base_bitset<_Nw>& __x) {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] &= __x._M_w[__i];
    }
  }

  void _M_do_or(const _Base_bitset<_Nw>& __x) {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] |= __x._M_w[__i];
    }
  }

  void _M_do_xor(const _Base_bitset<_Nw>& __x) {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] ^= __x._M_w[__i];
    }
  }

  void _M_do_left_shift(size_t __shift);
  void _M_do_right_shift(size_t __shift);

  void _M_do_flip() {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] = ~_M_w[__i];
    }
  }

  void _M_do_set() {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      _M_w[__i] = ~static_cast<_WordT>(0);
    }
  }

  void _M_do_reset() { memset(_M_w, 0, _Nw * sizeof(_WordT)); }

  bool _M_is_equal(const _Base_bitset<_Nw>& __x) const {
    for (size_t __i = 0; __i < _Nw; ++__i) {
      if (_M_w[__i] != __x._M_w[__i])
        return false;
    }
    return true;
  }

  bool _M_is_any() const {
    for ( size_t __i = 0; __i < _Nw; __i++ ) {
      if ( _M_w[__i] != static_cast<_WordT>(0) )
        return true;
    }
    return false;
  }

  size_t _M_do_count() const {
    size_t __result = 0;
    const unsigned char* __byte_ptr = (const unsigned char*)_M_w;
    const unsigned char* __end_ptr = (const unsigned char*)(_M_w+_Nw);

    while ( __byte_ptr < __end_ptr ) {
      __result += _Bit_count<true>::_S_bit_count[*__byte_ptr];
      __byte_ptr++;
    }
    return __result;
  }

  unsigned long _M_do_to_ulong() const; 

  // find first "on" bit
  size_t _M_do_find_first(size_t __not_found) const;

  // find the next "on" bit that follows "prev"
  size_t _M_do_find_next(size_t __prev, size_t __not_found) const;
};

//
// Definitions of non-inline functions from _Base_bitset.
// 

template<size_t _Nw>
void _Base_bitset<_Nw>::_M_do_left_shift(size_t __shift) 
{
  if (__shift != 0) {
    const size_t __wshift = __shift / __BITS_PER_WORD;
    const size_t __offset = __shift % __BITS_PER_WORD;

    if (__offset == 0)
      for (size_t __n = _Nw - 1; __n >= __wshift; --__n)
        _M_w[__n] = _M_w[__n - __wshift];

    else {
      const size_t __sub_offset = __BITS_PER_WORD - __offset;
      for (size_t __n = _Nw - 1; __n > __wshift; --__n)
        _M_w[__n] = (_M_w[__n - __wshift] << __offset) | 
                    (_M_w[__n - __wshift - 1] >> __sub_offset);
      _M_w[__wshift] = _M_w[0] << __offset;
    }

    fill(_M_w + 0, _M_w + __wshift, static_cast<_WordT>(0));
  }
}

template<size_t _Nw>
void _Base_bitset<_Nw>::_M_do_right_shift(size_t __shift) 
{
  if (__shift != 0) {
    const size_t __wshift = __shift / __BITS_PER_WORD;
    const size_t __offset = __shift % __BITS_PER_WORD;
    const size_t __limit = _Nw - __wshift - 1;

    if (__offset == 0)
      for (size_t __n = 0; __n <= __limit; ++__n)
        _M_w[__n] = _M_w[__n + __wshift];

    else {
      const size_t __sub_offset = __BITS_PER_WORD - __offset;
      for (size_t __n = 0; __n < __limit; ++__n)
        _M_w[__n] = (_M_w[__n + __wshift] >> __offset) |
                    (_M_w[__n + __wshift + 1] << __sub_offset);
      _M_w[__limit] = _M_w[_Nw-1] >> __offset;
    }

    fill(_M_w + __limit + 1, _M_w + _Nw, static_cast<_WordT>(0));
  }
}

template<size_t _Nw>
unsigned long _Base_bitset<_Nw>::_M_do_to_ulong() const
{
  for (size_t __i = 1; __i < _Nw; ++__i) 
    if (_M_w[__i]) 
      __STL_THROW(overflow_error("bitset"));
  
  return _M_w[0];
}

template<size_t _Nw>
size_t _Base_bitset<_Nw>::_M_do_find_first(size_t __not_found) const 
{
  for ( size_t __i = 0; __i < _Nw; __i++ ) {
    _WordT __thisword = _M_w[__i];
    if ( __thisword != static_cast<_WordT>(0) ) {
      // find byte within word
      for ( size_t __j = 0; __j < sizeof(_WordT); __j++ ) {
        unsigned char __this_byte
          = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
        if ( __this_byte )
          return __i*__BITS_PER_WORD + __j*CHAR_BIT +
            _First_one<true>::_S_first_one[__this_byte];

        __thisword >>= CHAR_BIT;
      }
    }
  }
  // not found, so return an indication of failure.
  return __not_found;
}

template<size_t _Nw>
size_t
_Base_bitset<_Nw>::_M_do_find_next(size_t __prev, size_t __not_found) const
{
  // make bound inclusive
  ++__prev;

  // check out of bounds
  if ( __prev >= _Nw * __BITS_PER_WORD )
    return __not_found;

    // search first word
  size_t __i = _S_whichword(__prev);
  _WordT __thisword = _M_w[__i];

    // mask off bits below bound
  __thisword &= (~static_cast<_WordT>(0)) << _S_whichbit(__prev);

  if ( __thisword != static_cast<_WordT>(0) ) {
    // find byte within word
    // get first byte into place
    __thisword >>= _S_whichbyte(__prev) * CHAR_BIT;
    for ( size_t __j = _S_whichbyte(__prev); __j < sizeof(_WordT); __j++ ) {
      unsigned char __this_byte
        = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
      if ( __this_byte )
        return __i*__BITS_PER_WORD + __j*CHAR_BIT +
          _First_one<true>::_S_first_one[__this_byte];

      __thisword >>= CHAR_BIT;
    }
  }

  // check subsequent words
  __i++;
  for ( ; __i < _Nw; __i++ ) {
    _WordT __thisword = _M_w[__i];
    if ( __thisword != static_cast<_WordT>(0) ) {
      // find byte within word
      for ( size_t __j = 0; __j < sizeof(_WordT); __j++ ) {
        unsigned char __this_byte
          = static_cast<unsigned char>(__thisword & (~(unsigned char)0));
        if ( __this_byte )
          return __i*__BITS_PER_WORD + __j*CHAR_BIT +
            _First_one<true>::_S_first_one[__this_byte];

        __thisword >>= CHAR_BIT;
      }
    }
  }

  // not found, so return an indication of failure.
  return __not_found;
} // end _M_do_find_next


// ------------------------------------------------------------

//
// Base class: specialization for a single word.
//

__STL_TEMPLATE_NULL struct _Base_bitset<1> {
  typedef unsigned long _WordT;
  _WordT _M_w;

  _Base_bitset( void ) : _M_w(0) {}
  _Base_bitset(unsigned long __val) : _M_w(__val) {}

  static size_t _S_whichword( size_t __pos )
    { return __pos / __BITS_PER_WORD; }
  static size_t _S_whichbyte( size_t __pos )
    { return (__pos % __BITS_PER_WORD) / CHAR_BIT; }
  static size_t _S_whichbit( size_t __pos )
    {  return __pos % __BITS_PER_WORD; }
  static _WordT _S_maskbit( size_t __pos )
    { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

  _WordT& _M_getword(size_t)       { return _M_w; }
  _WordT  _M_getword(size_t) const { return _M_w; }

  _WordT& _M_hiword()       { return _M_w; }
  _WordT  _M_hiword() const { return _M_w; }

  void _M_do_and(const _Base_bitset<1>& __x) { _M_w &= __x._M_w; }
  void _M_do_or(const _Base_bitset<1>& __x)  { _M_w |= __x._M_w; }
  void _M_do_xor(const _Base_bitset<1>& __x) { _M_w ^= __x._M_w; }
  void _M_do_left_shift(size_t __shift)     { _M_w <<= __shift; }
  void _M_do_right_shift(size_t __shift)    { _M_w >>= __shift; }
  void _M_do_flip()                       { _M_w = ~_M_w; }
  void _M_do_set()                        { _M_w = ~static_cast<_WordT>(0); }
  void _M_do_reset()                      { _M_w = 0; }

  bool _M_is_equal(const _Base_bitset<1>& __x) const
    { return _M_w == __x._M_w; }
  bool _M_is_any() const
    { return _M_w != 0; }

  size_t _M_do_count() const {
    size_t __result = 0;
    const unsigned char* __byte_ptr = (const unsigned char*)&_M_w;
    const unsigned char* __end_ptr
      = ((const unsigned char*)&_M_w)+sizeof(_M_w);
    while ( __byte_ptr < __end_ptr ) {
      __result += _Bit_count<true>::_S_bit_count[*__byte_ptr];
      __byte_ptr++;
    }