_bitset.h

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/*
 * Copyright (c) 1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Copyright (c) 1999
 * Boris Fomitchev
 *
 * 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_BITSET_H
#define _STLP_BITSET_H

// 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.


#ifndef _STLP_INTERNAL_ALGOBASE_H
#  include <stl/_algobase.h>
#endif

#ifndef _STLP_INTERNAL_ALLOC_H
#  include <stl/_alloc.h>
#endif

#ifndef _STLP_INTERNAL_ITERATOR_H
#  include <stl/_iterator.h>
#endif

#ifndef _STLP_INTERNAL_UNINITIALIZED_H
#  include <stl/_uninitialized.h>
#endif

#ifndef _STLP_RANGE_ERRORS_H
#  include <stl/_range_errors.h>
#endif

#ifndef _STLP_INTERNAL_STRING_H
#  include <stl/_string.h>
#endif

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

_STLP_BEGIN_NAMESPACE

_STLP_MOVE_TO_PRIV_NAMESPACE

// structure to aid in counting bits
class _STLP_CLASS_DECLSPEC _Bs_G
{
  public:
    //returns the number of bit set within the buffer between __beg and __end.
    static size_t _S_count(const unsigned char *__beg, const unsigned char *__end)
#if defined (_STLP_USE_NO_IOSTREAMS)
    {
      size_t __result = 0;
      for (; __beg != __end; ++__beg) {
        for (size_t i = 0; i < (sizeof(unsigned char) * 8); ++i) {
          if ((*__beg & (1 << i)) != 0) { ++__result; }
        }
      }
      return __result;
    }
#else
      ;
#endif
    // Mapping from 8 bit unsigned integers to the index of the first one bit set:
    static unsigned char _S_first_one(unsigned char __x)
#if defined (_STLP_USE_NO_IOSTREAMS)
    {
      for (unsigned char i = 0; i < (sizeof(unsigned char) * 8); ++i) {
        if ((__x & (1 << i)) != 0) { return i; }
      }
      return 0;
    }
#else
      ;
#endif
};

//
// 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() { _M_do_reset(); }

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

  static size_t _STLP_CALL _S_whichword( size_t __pos ) {
    return __pos / __BITS_PER_WORD;
  }
  static size_t _STLP_CALL _S_whichbyte( size_t __pos ) {
    return (__pos % __BITS_PER_WORD) / CHAR_BIT;
  }
  static size_t _STLP_CALL _S_whichbit( size_t __pos ) {
    return __pos % __BITS_PER_WORD;
  }
  static _WordT _STLP_CALL _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 {
    const unsigned char* __byte_ptr = (const unsigned char*)_M_w;
    const unsigned char* __end_ptr = (const unsigned char*)(_M_w+_Nw);

    return _Bs_G::_S_count(__byte_ptr, __end_ptr);
  }

  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;
};

//
// Base class: specialization for a single word.
//
_STLP_TEMPLATE_NULL
struct _Base_bitset<1UL> {
  typedef unsigned long _WordT;
  typedef _Base_bitset<1UL> _Self;

  _WordT _M_w;

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

  static size_t _STLP_CALL _S_whichword( size_t __pos ) {
    return __pos / __BITS_PER_WORD ;
  }
  static size_t _STLP_CALL _S_whichbyte( size_t __pos ) {
    return (__pos % __BITS_PER_WORD) / CHAR_BIT;
  }
  static size_t _STLP_CALL _S_whichbit( size_t __pos ) {
    return __pos % __BITS_PER_WORD;
  }
  static _WordT _STLP_CALL _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 _Self& __x) { _M_w &= __x._M_w; }
  void _M_do_or(const _Self& __x)  { _M_w |= __x._M_w; }
  void _M_do_xor(const _Self& __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 _Self& __x) const {
    return _M_w == __x._M_w;
  }
  bool _M_is_any() const {
    return _M_w != 0;
  }

  size_t _M_do_count() const {
    const unsigned char* __byte_ptr = (const unsigned char*)&_M_w;
    const unsigned char* __end_ptr = ((const unsigned char*)&_M_w)+sizeof(_M_w);
    return _Bs_G::_S_count(__byte_ptr, __end_ptr);
  }

  unsigned long _M_do_to_ulong() const { return _M_w; }

  inline size_t _M_do_find_first(size_t __not_found) const;

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


// ------------------------------------------------------------
//
// Definitions of should-be-non-inline functions from the single-word version of
//  _Base_bitset.
//
inline size_t
_Base_bitset<1UL>::_M_do_find_first(size_t __not_found) const {
  //  typedef unsigned long _WordT;
  _WordT __thisword = _M_w;

  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 __j*CHAR_BIT + _Bs_G::_S_first_one(__this_byte);

      __thisword >>= CHAR_BIT;
    }
  }
  // not found, so return a value that indicates failure.
  return __not_found;
}

inline size_t
_Base_bitset<1UL>::_M_do_find_next(size_t __prev,
                                   size_t __not_found ) const {
  // make bound inclusive
  ++__prev;

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

    // search first (and only) word
  _WordT __thisword = _M_w;

  // 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 __j*CHAR_BIT + _Bs_G::_S_first_one(__this_byte);

      __thisword >>= CHAR_BIT;
    }
  }

  // not found, so return a value that indicates failure.
  return __not_found;
} // end _M_do_find_next


// ------------------------------------------------------------
// Helper class to zero out the unused high-order bits in the highest word.

template <size_t _Extrabits> struct _Sanitize {
  static void _STLP_CALL _M_do_sanitize(unsigned long& __val)
  { __val &= ~((~__STATIC_CAST(unsigned long,0)) << _Extrabits); }
};

_STLP_TEMPLATE_NULL struct _Sanitize<0UL> {
  static void _STLP_CALL _M_do_sanitize(unsigned long) {}
};

_STLP_MOVE_TO_STD_NAMESPACE

// ------------------------------------------------------------
// Class bitset.
//   _Nb may be any nonzero number of type size_t.
template<size_t _Nb>
class bitset : public _STLP_PRIV _Base_bitset<__BITSET_WORDS(_Nb) > {
public:
  enum { _Words = __BITSET_WORDS(_Nb) } ;

private:
  typedef _STLP_PRIV _Base_bitset< _Words > _Base;

  void _M_do_sanitize() {
    _STLP_PRIV _Sanitize<_Nb%__BITS_PER_WORD >::_M_do_sanitize(this->_M_hiword());
  }
public:
  typedef unsigned long _WordT;
  struct reference;
  friend struct reference;

  // bit reference:
  struct reference {
  typedef _STLP_PRIV _Base_bitset<_Words > _Bitset_base;
  typedef bitset<_Nb> _Bitset;
    //    friend _Bitset;
    _WordT *_M_wp;
    size_t _M_bpos;

    // should be left undefined
    reference() {}

    reference( _Bitset& __b, size_t __pos ) {
      _M_wp = &__b._M_getword(__pos);
      _M_bpos = _Bitset_base::_S_whichbit(__pos);
    }

  public:
    ~reference() {}

    // for b[i] = __x;
    reference& operator=(bool __x) {
      if ( __x )
        *_M_wp |= _Bitset_base::_S_maskbit(_M_bpos);
      else
        *_M_wp &= ~_Bitset_base::_S_maskbit(_M_bpos);

      return *this;
    }

    // for b[i] = b[__j];
    reference& operator=(const reference& __j) {
      if ( (*(__j._M_wp) & _Bitset_base::_S_maskbit(__j._M_bpos)) )
        *_M_wp |= _Bitset_base::_S_maskbit(_M_bpos);
      else
        *_M_wp &= ~_Bitset_base::_S_maskbit(_M_bpos);

      return *this;
    }

    // flips the bit
    bool operator~() const { return (*(_M_wp) & _Bitset_base::_S_maskbit(_M_bpos)) == 0; }

    // for __x = b[i];
    operator bool() const { return (*(_M_wp) & _Bitset_base::_S_maskbit(_M_bpos)) != 0; }

    // for b[i].flip();
    reference& flip() {
      *_M_wp ^= _Bitset_base::_S_maskbit(_M_bpos);
      return *this;
    }
  };

  // 23.3.5.1 constructors:
  bitset() {}

  bitset(unsigned long __val) : _STLP_PRIV _Base_bitset<_Words>(__val) { _M_do_sanitize(); }

#if defined (_STLP_MEMBER_TEMPLATES)
  template<class _CharT, class _Traits, class _Alloc>
  explicit bitset(const basic_string<_CharT,_Traits,_Alloc>& __s,
                  size_t __pos = 0)
    : _STLP_PRIV _Base_bitset<_Words >() {
    if (__pos > __s.size())
      __stl_throw_out_of_range("bitset");
    _M_copy_from_string(__s, __pos,
                        basic_string<_CharT, _Traits, _Alloc>::npos);
  }
  template<class _CharT, class _Traits, class _Alloc>
  bitset(const basic_string<_CharT, _Traits, _Alloc>& __s,
          size_t __pos,
          size_t __n)
  : _STLP_PRIV _Base_bitset<_Words >() {
    if (__pos > __s.size())
      __stl_throw_out_of_range("bitset");
    _M_copy_from_string(__s, __pos, __n);
  }
#else /* _STLP_MEMBER_TEMPLATES */
  explicit bitset(const string& __s,
                  size_t __pos = 0,
                  size_t __n = (size_t)-1)