bitset

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00001 // <bitset> -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
00004 // 2011
00005 // Free Software Foundation, Inc.
00006 //
00007 // This file is part of the GNU ISO C++ Library.  This library is free
00008 // software; you can redistribute it and/or modify it under the
00009 // terms of the GNU General Public License as published by the
00010 // Free Software Foundation; either version 3, or (at your option)
00011 // any later version.
00012 
00013 // This library is distributed in the hope that it will be useful,
00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016 // GNU General Public License for more details.
00017 
00018 // Under Section 7 of GPL version 3, you are granted additional
00019 // permissions described in the GCC Runtime Library Exception, version
00020 // 3.1, as published by the Free Software Foundation.
00021 
00022 // You should have received a copy of the GNU General Public License and
00023 // a copy of the GCC Runtime Library Exception along with this program;
00024 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00025 // <http://www.gnu.org/licenses/>.
00026 
00027 /*
00028  * Copyright (c) 1998
00029  * Silicon Graphics Computer Systems, Inc.
00030  *
00031  * Permission to use, copy, modify, distribute and sell this software
00032  * and its documentation for any purpose is hereby granted without fee,
00033  * provided that the above copyright notice appear in all copies and
00034  * that both that copyright notice and this permission notice appear
00035  * in supporting documentation.  Silicon Graphics makes no
00036  * representations about the suitability of this software for any
00037  * purpose.  It is provided "as is" without express or implied warranty.
00038  */
00039 
00040 /** @file include/bitset
00041  *  This is a Standard C++ Library header.
00042  */
00043 
00044 #ifndef _GLIBCXX_BITSET
00045 #define _GLIBCXX_BITSET 1
00046 
00047 #pragma GCC system_header
00048 
00049 #include <string>
00050 #include <bits/functexcept.h>   // For invalid_argument, out_of_range,
00051                                 // overflow_error
00052 #include <iosfwd>
00053 #include <bits/cxxabi_forced.h>
00054 
00055 #define _GLIBCXX_BITSET_BITS_PER_WORD  (__CHAR_BIT__ * sizeof(unsigned long))
00056 #define _GLIBCXX_BITSET_WORDS(__n) \
00057   ((__n) / _GLIBCXX_BITSET_BITS_PER_WORD + \
00058    ((__n) % _GLIBCXX_BITSET_BITS_PER_WORD == 0 ? 0 : 1))
00059 
00060 namespace std _GLIBCXX_VISIBILITY(default)
00061 {
00062 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
00063 
00064   /**
00065    *  Base class, general case.  It is a class invariant that _Nw will be
00066    *  nonnegative.
00067    *
00068    *  See documentation for bitset.
00069   */
00070   template<size_t _Nw>
00071     struct _Base_bitset
00072     {
00073       typedef unsigned long _WordT;
00074 
00075       /// 0 is the least significant word.
00076       _WordT        _M_w[_Nw];
00077 
00078       _GLIBCXX_CONSTEXPR _Base_bitset()
00079       : _M_w() { }
00080 
00081 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00082       constexpr _Base_bitset(unsigned long long __val)
00083       : _M_w({ _WordT(__val)
00084 #if __SIZEOF_LONG_LONG__ > __SIZEOF_LONG__
00085            , _WordT(__val >> _GLIBCXX_BITSET_BITS_PER_WORD)
00086 #endif
00087        }) { }
00088 #else
00089       _Base_bitset(unsigned long __val)
00090       : _M_w()
00091       { _M_w[0] = __val; }
00092 #endif
00093 
00094       static _GLIBCXX_CONSTEXPR size_t
00095       _S_whichword(size_t __pos )
00096       { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }
00097 
00098       static _GLIBCXX_CONSTEXPR size_t
00099       _S_whichbyte(size_t __pos )
00100       { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }
00101 
00102       static _GLIBCXX_CONSTEXPR size_t
00103       _S_whichbit(size_t __pos )
00104       { return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }
00105 
00106       static _GLIBCXX_CONSTEXPR _WordT
00107       _S_maskbit(size_t __pos )
00108       { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }
00109 
00110       _WordT&
00111       _M_getword(size_t __pos)
00112       { return _M_w[_S_whichword(__pos)]; }
00113 
00114       _WordT
00115       _M_getword(size_t __pos) const
00116       { return _M_w[_S_whichword(__pos)]; }
00117 
00118 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00119       const _WordT*
00120       _M_getdata() const
00121       { return _M_w; }
00122 #endif
00123 
00124       _WordT&
00125       _M_hiword()
00126       { return _M_w[_Nw - 1]; }
00127 
00128       _GLIBCXX_CONSTEXPR _WordT
00129       _M_hiword() const
00130       { return _M_w[_Nw - 1]; }
00131 
00132       void
00133       _M_do_and(const _Base_bitset<_Nw>& __x)
00134       {
00135     for (size_t __i = 0; __i < _Nw; __i++)
00136       _M_w[__i] &= __x._M_w[__i];
00137       }
00138 
00139       void
00140       _M_do_or(const _Base_bitset<_Nw>& __x)
00141       {
00142     for (size_t __i = 0; __i < _Nw; __i++)
00143       _M_w[__i] |= __x._M_w[__i];
00144       }
00145 
00146       void
00147       _M_do_xor(const _Base_bitset<_Nw>& __x)
00148       {
00149     for (size_t __i = 0; __i < _Nw; __i++)
00150       _M_w[__i] ^= __x._M_w[__i];
00151       }
00152 
00153       void
00154       _M_do_left_shift(size_t __shift);
00155 
00156       void
00157       _M_do_right_shift(size_t __shift);
00158 
00159       void
00160       _M_do_flip()
00161       {
00162     for (size_t __i = 0; __i < _Nw; __i++)
00163       _M_w[__i] = ~_M_w[__i];
00164       }
00165 
00166       void
00167       _M_do_set()
00168       {
00169     for (size_t __i = 0; __i < _Nw; __i++)
00170       _M_w[__i] = ~static_cast<_WordT>(0);
00171       }
00172 
00173       void
00174       _M_do_reset()
00175       { __builtin_memset(_M_w, 0, _Nw * sizeof(_WordT)); }
00176 
00177       bool
00178       _M_is_equal(const _Base_bitset<_Nw>& __x) const
00179       {
00180     for (size_t __i = 0; __i < _Nw; ++__i)
00181       if (_M_w[__i] != __x._M_w[__i])
00182         return false;
00183     return true;
00184       }
00185 
00186       size_t
00187       _M_are_all_aux() const
00188       {
00189     for (size_t __i = 0; __i < _Nw - 1; __i++)
00190       if (_M_w[__i] != ~static_cast<_WordT>(0))
00191         return 0;
00192     return ((_Nw - 1) * _GLIBCXX_BITSET_BITS_PER_WORD
00193         + __builtin_popcountl(_M_hiword()));
00194       }
00195 
00196       bool
00197       _M_is_any() const
00198       {
00199     for (size_t __i = 0; __i < _Nw; __i++)
00200       if (_M_w[__i] != static_cast<_WordT>(0))
00201         return true;
00202     return false;
00203       }
00204 
00205       size_t
00206       _M_do_count() const
00207       {
00208     size_t __result = 0;
00209     for (size_t __i = 0; __i < _Nw; __i++)
00210       __result += __builtin_popcountl(_M_w[__i]);
00211     return __result;
00212       }
00213 
00214       unsigned long
00215       _M_do_to_ulong() const;
00216 
00217 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00218       unsigned long long
00219       _M_do_to_ullong() const;
00220 #endif
00221 
00222       // find first "on" bit
00223       size_t
00224       _M_do_find_first(size_t __not_found) const;
00225 
00226       // find the next "on" bit that follows "prev"
00227       size_t
00228       _M_do_find_next(size_t __prev, size_t __not_found) const;
00229     };
00230 
00231   // Definitions of non-inline functions from _Base_bitset.
00232   template<size_t _Nw>
00233     void
00234     _Base_bitset<_Nw>::_M_do_left_shift(size_t __shift)
00235     {
00236       if (__builtin_expect(__shift != 0, 1))
00237     {
00238       const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
00239       const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;
00240 
00241       if (__offset == 0)
00242         for (size_t __n = _Nw - 1; __n >= __wshift; --__n)
00243           _M_w[__n] = _M_w[__n - __wshift];
00244       else
00245         {
00246           const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD 
00247                        - __offset);
00248           for (size_t __n = _Nw - 1; __n > __wshift; --__n)
00249         _M_w[__n] = ((_M_w[__n - __wshift] << __offset)
00250                  | (_M_w[__n - __wshift - 1] >> __sub_offset));
00251           _M_w[__wshift] = _M_w[0] << __offset;
00252         }
00253 
00254       std::fill(_M_w + 0, _M_w + __wshift, static_cast<_WordT>(0));
00255     }
00256     }
00257 
00258   template<size_t _Nw>
00259     void
00260     _Base_bitset<_Nw>::_M_do_right_shift(size_t __shift)
00261     {
00262       if (__builtin_expect(__shift != 0, 1))
00263     {
00264       const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
00265       const size_t __offset = __shift % _GLIBCXX_BITSET_BITS_PER_WORD;
00266       const size_t __limit = _Nw - __wshift - 1;
00267 
00268       if (__offset == 0)
00269         for (size_t __n = 0; __n <= __limit; ++__n)
00270           _M_w[__n] = _M_w[__n + __wshift];
00271       else
00272         {
00273           const size_t __sub_offset = (_GLIBCXX_BITSET_BITS_PER_WORD
00274                        - __offset);
00275           for (size_t __n = 0; __n < __limit; ++__n)
00276         _M_w[__n] = ((_M_w[__n + __wshift] >> __offset)
00277                  | (_M_w[__n + __wshift + 1] << __sub_offset));
00278           _M_w[__limit] = _M_w[_Nw-1] >> __offset;
00279         }
00280       
00281       std::fill(_M_w + __limit + 1, _M_w + _Nw, static_cast<_WordT>(0));
00282     }
00283     }
00284 
00285   template<size_t _Nw>
00286     unsigned long
00287     _Base_bitset<_Nw>::_M_do_to_ulong() const
00288     {
00289       for (size_t __i = 1; __i < _Nw; ++__i)
00290     if (_M_w[__i])
00291       __throw_overflow_error(__N("_Base_bitset::_M_do_to_ulong"));
00292       return _M_w[0];
00293     }
00294 
00295 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00296   template<size_t _Nw>
00297     unsigned long long
00298     _Base_bitset<_Nw>::_M_do_to_ullong() const
00299     {
00300       const bool __dw = sizeof(unsigned long long) > sizeof(unsigned long);
00301       for (size_t __i = 1 + __dw; __i < _Nw; ++__i)
00302     if (_M_w[__i])
00303       __throw_overflow_error(__N("_Base_bitset::_M_do_to_ullong"));
00304 
00305       if (__dw)
00306     return _M_w[0] + (static_cast<unsigned long long>(_M_w[1])
00307               << _GLIBCXX_BITSET_BITS_PER_WORD);
00308       return _M_w[0];
00309     }
00310 #endif
00311 
00312   template<size_t _Nw>
00313     size_t
00314     _Base_bitset<_Nw>::_M_do_find_first(size_t __not_found) const
00315     {
00316       for (size_t __i = 0; __i < _Nw; __i++)
00317     {
00318       _WordT __thisword = _M_w[__i];
00319       if (__thisword != static_cast<_WordT>(0))
00320         return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
00321             + __builtin_ctzl(__thisword));
00322     }
00323       // not found, so return an indication of failure.
00324       return __not_found;
00325     }
00326 
00327   template<size_t _Nw>
00328     size_t
00329     _Base_bitset<_Nw>::_M_do_find_next(size_t __prev, size_t __not_found) const
00330     {
00331       // make bound inclusive
00332       ++__prev;
00333 
00334       // check out of bounds
00335       if (__prev >= _Nw * _GLIBCXX_BITSET_BITS_PER_WORD)
00336     return __not_found;
00337 
00338       // search first word
00339       size_t __i = _S_whichword(__prev);
00340       _WordT __thisword = _M_w[__i];
00341 
00342       // mask off bits below bound
00343       __thisword &= (~static_cast<_WordT>(0)) << _S_whichbit(__prev);
00344 
00345       if (__thisword != static_cast<_WordT>(0))
00346     return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
00347         + __builtin_ctzl(__thisword));
00348 
00349       // check subsequent words
00350       __i++;
00351       for (; __i < _Nw; __i++)
00352     {
00353       __thisword = _M_w[__i];
00354       if (__thisword != static_cast<_WordT>(0))
00355         return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
00356             + __builtin_ctzl(__thisword));
00357     }
00358       // not found, so return an indication of failure.
00359       return __not_found;
00360     } // end _M_do_find_next
00361 
00362   /**
00363    *  Base class, specialization for a single word.
00364    *
00365    *  See documentation for bitset.
00366   */
00367   template<>
00368     struct _Base_bitset<1>
00369     {
00370       typedef unsigned long _WordT;
00371       _WordT _M_w;
00372 
00373       _GLIBCXX_CONSTEXPR _Base_bitset()
00374       : _M_w(0)
00375       { }
00376 
00377 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00378       constexpr _Base_bitset(unsigned long long __val)
00379 #else
00380       _Base_bitset(unsigned long __val)
00381 #endif
00382       : _M_w(__val)
00383       { }
00384 
00385       static _GLIBCXX_CONSTEXPR size_t
00386       _S_whichword(size_t __pos )
00387       { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }
00388 
00389       static _GLIBCXX_CONSTEXPR size_t
00390       _S_whichbyte(size_t __pos )
00391       { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }
00392 
00393       static _GLIBCXX_CONSTEXPR size_t
00394       _S_whichbit(size_t __pos )
00395       {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }
00396 
00397       static _GLIBCXX_CONSTEXPR _WordT
00398       _S_maskbit(size_t __pos )
00399       { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }
00400 
00401       _WordT&
00402       _M_getword(size_t)
00403       { return _M_w; }
00404 
00405       _WordT
00406       _M_getword(size_t) const
00407       { return _M_w; }
00408 
00409 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00410       const _WordT*
00411       _M_getdata() const
00412       { return &_M_w; }
00413 #endif
00414 
00415       _WordT&
00416       _M_hiword()
00417       { return _M_w; }
00418 
00419       _GLIBCXX_CONSTEXPR _WordT
00420       _M_hiword() const
00421       { return _M_w; }
00422 
00423       void
00424       _M_do_and(const _Base_bitset<1>& __x)
00425       { _M_w &= __x._M_w; }
00426 
00427       void
00428       _M_do_or(const _Base_bitset<1>& __x)
00429       { _M_w |= __x._M_w; }
00430 
00431       void
00432       _M_do_xor(const _Base_bitset<1>& __x)
00433       { _M_w ^= __x._M_w; }
00434 
00435       void
00436       _M_do_left_shift(size_t __shift)
00437       { _M_w <<= __shift; }
00438 
00439       void
00440       _M_do_right_shift(size_t __shift)
00441       { _M_w >>= __shift; }
00442 
00443       void
00444       _M_do_flip()
00445       { _M_w = ~_M_w; }
00446 
00447       void
00448       _M_do_set()
00449       { _M_w = ~static_cast<_WordT>(0); }
00450 
00451       void
00452       _M_do_reset()
00453       { _M_w = 0; }
00454 
00455       bool
00456       _M_is_equal(const _Base_bitset<1>& __x) const
00457       { return _M_w == __x._M_w; }
00458 
00459       size_t
00460       _M_are_all_aux() const
00461       { return __builtin_popcountl(_M_w); }
00462 
00463       bool
00464       _M_is_any() const
00465       { return _M_w != 0; }
00466 
00467       size_t
00468       _M_do_count() const
00469       { return __builtin_popcountl(_M_w); }
00470 
00471       unsigned long
00472       _M_do_to_ulong() const
00473       { return _M_w; }
00474 
00475 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00476       unsigned long long
00477       _M_do_to_ullong() const
00478       { return _M_w; }
00479 #endif
00480 
00481       size_t
00482       _M_do_find_first(size_t __not_found) const
00483       {
00484         if (_M_w != 0)
00485           return __builtin_ctzl(_M_w);
00486         else
00487           return __not_found;
00488       }
00489 
00490       // find the next "on" bit that follows "prev"
00491       size_t
00492       _M_do_find_next(size_t __prev, size_t __not_found) const
00493       {
00494     ++__prev;
00495     if (__prev >= ((size_t) _GLIBCXX_BITSET_BITS_PER_WORD))
00496       return __not_found;
00497 
00498     _WordT __x = _M_w >> __prev;
00499     if (__x != 0)
00500       return __builtin_ctzl(__x) + __prev;
00501     else
00502       return __not_found;
00503       }
00504     };
00505 
00506   /**
00507    *  Base class, specialization for no storage (zero-length %bitset).
00508    *
00509    *  See documentation for bitset.
00510   */
00511   template<>
00512     struct _Base_bitset<0>
00513     {
00514       typedef unsigned long _WordT;
00515 
00516       _GLIBCXX_CONSTEXPR _Base_bitset()
00517       { }
00518 
00519 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00520       constexpr _Base_bitset(unsigned long long)
00521 #else
00522       _Base_bitset(unsigned long)
00523 #endif
00524       { }
00525 
00526       static _GLIBCXX_CONSTEXPR size_t
00527       _S_whichword(size_t __pos )
00528       { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }
00529 
00530       static _GLIBCXX_CONSTEXPR size_t
00531       _S_whichbyte(size_t __pos )
00532       { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }
00533 
00534       static _GLIBCXX_CONSTEXPR size_t
00535       _S_whichbit(size_t __pos )
00536       {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }
00537 
00538       static _GLIBCXX_CONSTEXPR _WordT
00539       _S_maskbit(size_t __pos )
00540       { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }
00541 
00542       // This would normally give access to the data.  The bounds-checking
00543       // in the bitset class will prevent the user from getting this far,
00544       // but (1) it must still return an lvalue to compile, and (2) the
00545       // user might call _Unchecked_set directly, in which case this /needs/
00546       // to fail.  Let's not penalize zero-length users unless they actually
00547       // make an unchecked call; all the memory ugliness is therefore
00548       // localized to this single should-never-get-this-far function.
00549       _WordT&
00550       _M_getword(size_t)
00551       { 
00552     __throw_out_of_range(__N("_Base_bitset::_M_getword")); 
00553     return *new _WordT; 
00554       }
00555 
00556       _WordT
00557       _M_getword(size_t __pos) const
00558       { return 0; }
00559 
00560       _GLIBCXX_CONSTEXPR _WordT
00561       _M_hiword() const
00562       { return 0; }
00563 
00564       void
00565       _M_do_and(const _Base_bitset<0>&)
00566       { }
00567 
00568       void
00569       _M_do_or(const _Base_bitset<0>&)
00570       { }
00571 
00572       void
00573       _M_do_xor(const _Base_bitset<0>&)
00574       { }
00575 
00576       void
00577       _M_do_left_shift(size_t)
00578       { }
00579 
00580       void
00581       _M_do_right_shift(size_t)
00582       { }
00583 
00584       void
00585       _M_do_flip()
00586       { }
00587 
00588       void
00589       _M_do_set()
00590       { }
00591 
00592       void
00593       _M_do_reset()
00594       { }
00595 
00596       // Are all empty bitsets equal to each other?  Are they equal to
00597       // themselves?  How to compare a thing which has no state?  What is
00598       // the sound of one zero-length bitset clapping?
00599       bool
00600       _M_is_equal(const _Base_bitset<0>&) const
00601       { return true; }
00602 
00603       size_t
00604       _M_are_all_aux() const
00605       { return 0; }
00606 
00607       bool
00608       _M_is_any() const
00609       { return false; }
00610 
00611       size_t
00612       _M_do_count() const
00613       { return 0; }
00614 
00615       unsigned long
00616       _M_do_to_ulong() const
00617       { return 0; }
00618 
00619 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00620       unsigned long long
00621       _M_do_to_ullong() const
00622       { return 0; }
00623 #endif
00624 
00625       // Normally "not found" is the size, but that could also be
00626       // misinterpreted as an index in this corner case.  Oh well.
00627       size_t
00628       _M_do_find_first(size_t) const
00629       { return 0; }
00630 
00631       size_t
00632       _M_do_find_next(size_t, size_t) const
00633       { return 0; }
00634     };
00635 
00636 
00637   // Helper class to zero out the unused high-order bits in the highest word.
00638   template<size_t _Extrabits>
00639     struct _Sanitize
00640     {
00641       typedef unsigned long _WordT;
00642 
00643       static void 
00644       _S_do_sanitize(_WordT& __val)
00645       { __val &= ~((~static_cast<_WordT>(0)) << _Extrabits); }
00646     };
00647 
00648   template<>
00649     struct _Sanitize<0>
00650     { 
00651       typedef unsigned long _WordT;
00652 
00653       static void 
00654       _S_do_sanitize(_WordT) { } 
00655     };
00656 
00657   /**
00658    *  @brief  The %bitset class represents a @e fixed-size sequence of bits.
00659    *
00660    *  @ingroup containers
00661    *
00662    *  (Note that %bitset does @e not meet the formal requirements of a
00663    *  <a href="tables.html#65">container</a>.  Mainly, it lacks iterators.)
00664    *
00665    *  The template argument, @a Nb, may be any non-negative number,
00666    *  specifying the number of bits (e.g., "0", "12", "1024*1024").
00667    *
00668    *  In the general unoptimized case, storage is allocated in word-sized
00669    *  blocks.  Let B be the number of bits in a word, then (Nb+(B-1))/B
00670    *  words will be used for storage.  B - Nb%B bits are unused.  (They are
00671    *  the high-order bits in the highest word.)  It is a class invariant
00672    *  that those unused bits are always zero.
00673    *
00674    *  If you think of %bitset as <em>a simple array of bits</em>, be
00675    *  aware that your mental picture is reversed: a %bitset behaves
00676    *  the same way as bits in integers do, with the bit at index 0 in
00677    *  the <em>least significant / right-hand</em> position, and the bit at
00678    *  index Nb-1 in the <em>most significant / left-hand</em> position.
00679    *  Thus, unlike other containers, a %bitset's index <em>counts from
00680    *  right to left</em>, to put it very loosely.
00681    *
00682    *  This behavior is preserved when translating to and from strings.  For
00683    *  example, the first line of the following program probably prints
00684    *  <em>b(&apos;a&apos;) is 0001100001</em> on a modern ASCII system.
00685    *
00686    *  @code
00687    *     #include <bitset>
00688    *     #include <iostream>
00689    *     #include <sstream>
00690    *
00691    *     using namespace std;
00692    *
00693    *     int main()
00694    *     {
00695    *         long         a = 'a';
00696    *         bitset<10>   b(a);
00697    *
00698    *         cout << "b('a') is " << b << endl;
00699    *
00700    *         ostringstream s;
00701    *         s << b;
00702    *         string  str = s.str();
00703    *         cout << "index 3 in the string is " << str[3] << " but\n"
00704    *              << "index 3 in the bitset is " << b[3] << endl;
00705    *     }
00706    *  @endcode
00707    *
00708    *  Also see:
00709    *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt12ch33s02.html
00710    *  for a description of extensions.
00711    *
00712    *  Most of the actual code isn't contained in %bitset<> itself, but in the
00713    *  base class _Base_bitset.  The base class works with whole words, not with
00714    *  individual bits.  This allows us to specialize _Base_bitset for the
00715    *  important special case where the %bitset is only a single word.
00716    *
00717    *  Extra confusion can result due to the fact that the storage for
00718    *  _Base_bitset @e is a regular array, and is indexed as such.  This is
00719    *  carefully encapsulated.
00720   */
00721   template<size_t _Nb>
00722     class bitset
00723     : private _Base_bitset<_GLIBCXX_BITSET_WORDS(_Nb)>
00724     {
00725     private:
00726       typedef _Base_bitset<_GLIBCXX_BITSET_WORDS(_Nb)> _Base;
00727       typedef unsigned long _WordT;
00728 
00729       void
00730       _M_do_sanitize()
00731       { 
00732     typedef _Sanitize<_Nb % _GLIBCXX_BITSET_BITS_PER_WORD> __sanitize_type;
00733     __sanitize_type::_S_do_sanitize(this->_M_hiword());
00734       }
00735 
00736 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00737       template<typename> friend class hash;
00738 #endif
00739 
00740     public:
00741       /**
00742        *  This encapsulates the concept of a single bit.  An instance of this
00743        *  class is a proxy for an actual bit; this way the individual bit
00744        *  operations are done as faster word-size bitwise instructions.
00745        *
00746        *  Most users will never need to use this class directly; conversions
00747        *  to and from bool are automatic and should be transparent.  Overloaded
00748        *  operators help to preserve the illusion.
00749        *
00750        *  (On a typical system, this <em>bit %reference</em> is 64
00751        *  times the size of an actual bit.  Ha.)
00752        */
00753       class reference
00754       {
00755     friend class bitset;
00756 
00757     _WordT* _M_wp;
00758     size_t  _M_bpos;
00759     
00760     // left undefined
00761     reference();
00762     
00763       public:
00764     reference(bitset& __b, size_t __pos)
00765     {
00766       _M_wp = &__b._M_getword(__pos);
00767       _M_bpos = _Base::_S_whichbit(__pos);
00768     }
00769 
00770     ~reference()
00771     { }
00772 
00773     // For b[i] = __x;
00774     reference&
00775     operator=(bool __x)
00776     {
00777       if (__x)
00778         *_M_wp |= _Base::_S_maskbit(_M_bpos);
00779       else
00780         *_M_wp &= ~_Base::_S_maskbit(_M_bpos);
00781       return *this;
00782     }
00783 
00784     // For b[i] = b[__j];
00785     reference&
00786     operator=(const reference& __j)
00787     {
00788       if ((*(__j._M_wp) & _Base::_S_maskbit(__j._M_bpos)))
00789         *_M_wp |= _Base::_S_maskbit(_M_bpos);
00790       else
00791         *_M_wp &= ~_Base::_S_maskbit(_M_bpos);
00792       return *this;
00793     }
00794 
00795     // Flips the bit
00796     bool
00797     operator~() const
00798     { return (*(_M_wp) & _Base::_S_maskbit(_M_bpos)) == 0; }
00799 
00800     // For __x = b[i];
00801     operator bool() const
00802     { return (*(_M_wp) & _Base::_S_maskbit(_M_bpos)) != 0; }
00803 
00804     // For b[i].flip();
00805     reference&
00806     flip()
00807     {
00808       *_M_wp ^= _Base::_S_maskbit(_M_bpos);
00809       return *this;
00810     }
00811       };
00812       friend class reference;
00813 
00814       // 23.3.5.1 constructors:
00815       /// All bits set to zero.
00816       _GLIBCXX_CONSTEXPR bitset()
00817       { }
00818 
00819       /// Initial bits bitwise-copied from a single word (others set to zero).
00820 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00821       constexpr bitset(unsigned long long __val)
00822       : _Base(__val) { }
00823 #else
00824       bitset(unsigned long __val)
00825       : _Base(__val)
00826       { _M_do_sanitize(); }
00827 #endif
00828 
00829       /**
00830        *  @brief  Use a subset of a string.
00831        *  @param  s  A string of @a 0 and @a 1 characters.
00832        *  @param  position  Index of the first character in @a s to use;
00833        *                    defaults to zero.
00834        *  @throw  std::out_of_range  If @a pos is bigger the size of @a s.
00835        *  @throw  std::invalid_argument  If a character appears in the string
00836        *                                 which is neither @a 0 nor @a 1.
00837        */
00838       template<class _CharT, class _Traits, class _Alloc>
00839     explicit
00840     bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
00841            size_t __position = 0)
00842     : _Base()
00843     {
00844       if (__position > __s.size())
00845         __throw_out_of_range(__N("bitset::bitset initial position "
00846                      "not valid"));
00847       _M_copy_from_string(__s, __position,
00848                   std::basic_string<_CharT, _Traits, _Alloc>::npos,
00849                   _CharT('0'), _CharT('1'));
00850     }
00851 
00852       /**
00853        *  @brief  Use a subset of a string.
00854        *  @param  s  A string of @a 0 and @a 1 characters.
00855        *  @param  position  Index of the first character in @a s to use.
00856        *  @param  n    The number of characters to copy.
00857        *  @throw  std::out_of_range  If @a pos is bigger the size of @a s.
00858        *  @throw  std::invalid_argument  If a character appears in the string
00859        *                                 which is neither @a 0 nor @a 1.
00860        */
00861       template<class _CharT, class _Traits, class _Alloc>
00862     bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
00863            size_t __position, size_t __n)
00864     : _Base()
00865     {
00866       if (__position > __s.size())
00867         __throw_out_of_range(__N("bitset::bitset initial position "
00868                      "not valid"));
00869       _M_copy_from_string(__s, __position, __n, _CharT('0'), _CharT('1'));
00870     }
00871 
00872       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00873       // 396. what are characters zero and one.
00874       template<class _CharT, class _Traits, class _Alloc>
00875     bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
00876            size_t __position, size_t __n,
00877            _CharT __zero, _CharT __one = _CharT('1'))
00878     : _Base()
00879     {
00880       if (__position > __s.size())
00881         __throw_out_of_range(__N("bitset::bitset initial position "
00882                      "not valid"));
00883       _M_copy_from_string(__s, __position, __n, __zero, __one);
00884     }
00885 
00886 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00887       /**
00888        *  @brief  Construct from a character %array.
00889        *  @param  str  An %array of characters @a zero and @a one.
00890        *  @param  n    The number of characters to use.
00891        *  @param  zero The character corresponding to the value 0.
00892        *  @param  one  The character corresponding to the value 1.
00893        *  @throw  std::invalid_argument  If a character appears in the string
00894        *                                 which is neither @a zero nor @a one.
00895        */
00896       template<typename _CharT>
00897         explicit
00898         bitset(const _CharT* __str,
00899            typename std::basic_string<_CharT>::size_type __n
00900            = std::basic_string<_CharT>::npos,
00901            _CharT __zero = _CharT('0'), _CharT __one = _CharT('1'))
00902         : _Base()
00903         {
00904       if (!__str)
00905         __throw_logic_error(__N("bitset::bitset(const _CharT*, ...)"));
00906 
00907       if (__n == std::basic_string<_CharT>::npos)
00908         __n = std::char_traits<_CharT>::length(__str);
00909       _M_copy_from_ptr<_CharT, std::char_traits<_CharT>>(__str, __n, 0,
00910                                  __n, __zero,
00911                                  __one);
00912     }
00913 #endif
00914 
00915       // 23.3.5.2 bitset operations:
00916       //@{
00917       /**
00918        *  @brief  Operations on bitsets.
00919        *  @param  rhs  A same-sized bitset.
00920        *
00921        *  These should be self-explanatory.
00922        */
00923       bitset<_Nb>&
00924       operator&=(const bitset<_Nb>& __rhs)
00925       {
00926     this->_M_do_and(__rhs);
00927     return *this;
00928       }
00929 
00930       bitset<_Nb>&
00931       operator|=(const bitset<_Nb>& __rhs)
00932       {
00933     this->_M_do_or(__rhs);
00934     return *this;
00935       }
00936 
00937       bitset<_Nb>&
00938       operator^=(const bitset<_Nb>& __rhs)
00939       {
00940     this->_M_do_xor(__rhs);
00941     return *this;
00942       }
00943       //@}
00944       
00945       //@{
00946       /**
00947        *  @brief  Operations on bitsets.
00948        *  @param  position  The number of places to shift.
00949        *
00950        *  These should be self-explanatory.
00951        */
00952       bitset<_Nb>&
00953       operator<<=(size_t __position)
00954       {
00955     if (__builtin_expect(__position < _Nb, 1))
00956       {
00957         this->_M_do_left_shift(__position);
00958         this->_M_do_sanitize();
00959       }
00960     else
00961       this->_M_do_reset();
00962     return *this;
00963       }
00964 
00965       bitset<_Nb>&
00966       operator>>=(size_t __position)
00967       {
00968     if (__builtin_expect(__position < _Nb, 1))
00969       {
00970         this->_M_do_right_shift(__position);
00971         this->_M_do_sanitize();
00972       }
00973     else
00974       this->_M_do_reset();
00975     return *this;
00976       }
00977       //@}
00978       
00979       //@{
00980       /**
00981        *  These versions of single-bit set, reset, flip, and test are
00982        *  extensions from the SGI version.  They do no range checking.
00983        *  @ingroup SGIextensions
00984        */
00985       bitset<_Nb>&
00986       _Unchecked_set(size_t __pos)
00987       {
00988     this->_M_getword(__pos) |= _Base::_S_maskbit(__pos);
00989     return *this;
00990       }
00991 
00992       bitset<_Nb>&
00993       _Unchecked_set(size_t __pos, int __val)
00994       {
00995     if (__val)
00996       this->_M_getword(__pos) |= _Base::_S_maskbit(__pos);
00997     else
00998       this->_M_getword(__pos) &= ~_Base::_S_maskbit(__pos);
00999     return *this;
01000       }
01001 
01002       bitset<_Nb>&
01003       _Unchecked_reset(size_t __pos)
01004       {
01005     this->_M_getword(__pos) &= ~_Base::_S_maskbit(__pos);
01006     return *this;
01007       }
01008 
01009       bitset<_Nb>&
01010       _Unchecked_flip(size_t __pos)
01011       {
01012     this->_M_getword(__pos) ^= _Base::_S_maskbit(__pos);
01013     return *this;
01014       }
01015 
01016       bool
01017       _Unchecked_test(size_t __pos) const
01018       { return ((this->_M_getword(__pos) & _Base::_S_maskbit(__pos))
01019         != static_cast<_WordT>(0)); }
01020       //@}
01021       
01022       // Set, reset, and flip.
01023       /**
01024        *  @brief Sets every bit to true.
01025        */
01026       bitset<_Nb>&
01027       set()
01028       {
01029     this->_M_do_set();
01030     this->_M_do_sanitize();
01031     return *this;
01032       }
01033 
01034       /**
01035        *  @brief Sets a given bit to a particular value.
01036        *  @param  position  The index of the bit.
01037        *  @param  val  Either true or false, defaults to true.
01038        *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
01039        */
01040       bitset<_Nb>&
01041       set(size_t __position, bool __val = true)
01042       {
01043     if (__position >= _Nb)
01044       __throw_out_of_range(__N("bitset::set"));
01045     return _Unchecked_set(__position, __val);
01046       }
01047 
01048       /**
01049        *  @brief Sets every bit to false.
01050        */
01051       bitset<_Nb>&
01052       reset()
01053       {
01054     this->_M_do_reset();
01055     return *this;
01056       }
01057 
01058       /**
01059        *  @brief Sets a given bit to false.
01060        *  @param  position  The index of the bit.
01061        *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
01062        *
01063        *  Same as writing @c set(pos,false).
01064        */
01065       bitset<_Nb>&
01066       reset(size_t __position)
01067       {
01068     if (__position >= _Nb)
01069       __throw_out_of_range(__N("bitset::reset"));
01070     return _Unchecked_reset(__position);
01071       }
01072       
01073       /**
01074        *  @brief Toggles every bit to its opposite value.
01075        */
01076       bitset<_Nb>&
01077       flip()
01078       {
01079     this->_M_do_flip();
01080     this->_M_do_sanitize();
01081     return *this;
01082       }
01083 
01084       /**
01085        *  @brief Toggles a given bit to its opposite value.
01086        *  @param  position  The index of the bit.
01087        *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
01088        */
01089       bitset<_Nb>&
01090       flip(size_t __position)
01091       {
01092     if (__position >= _Nb)
01093       __throw_out_of_range(__N("bitset::flip"));
01094     return _Unchecked_flip(__position);
01095       }
01096       
01097       /// See the no-argument flip().
01098       bitset<_Nb>
01099       operator~() const
01100       { return bitset<_Nb>(*this).flip(); }
01101 
01102       //@{
01103       /**
01104        *  @brief  Array-indexing support.
01105        *  @param  position  Index into the %bitset.
01106        *  @return A bool for a <em>const %bitset</em>.  For non-const
01107        *           bitsets, an instance of the reference proxy class.
01108        *  @note  These operators do no range checking and throw no exceptions,
01109        *         as required by DR 11 to the standard.
01110        *
01111        *  _GLIBCXX_RESOLVE_LIB_DEFECTS Note that this implementation already
01112        *  resolves DR 11 (items 1 and 2), but does not do the range-checking
01113        *  required by that DR's resolution.  -pme
01114        *  The DR has since been changed:  range-checking is a precondition
01115        *  (users' responsibility), and these functions must not throw.  -pme
01116        */
01117       reference
01118       operator[](size_t __position)
01119       { return reference(*this, __position); }
01120 
01121       bool
01122       operator[](size_t __position) const
01123       { return _Unchecked_test(__position); }
01124       //@}
01125       
01126       /**
01127        *  @brief Returns a numerical interpretation of the %bitset.
01128        *  @return  The integral equivalent of the bits.
01129        *  @throw  std::overflow_error  If there are too many bits to be
01130        *                               represented in an @c unsigned @c long.
01131        */
01132       unsigned long
01133       to_ulong() const
01134       { return this->_M_do_to_ulong(); }
01135 
01136 #ifdef __GXX_EXPERIMENTAL_CXX0X__
01137       unsigned long long
01138       to_ullong() const
01139       { return this->_M_do_to_ullong(); }
01140 #endif
01141 
01142       /**
01143        *  @brief Returns a character interpretation of the %bitset.
01144        *  @return  The string equivalent of the bits.
01145        *
01146        *  Note the ordering of the bits:  decreasing character positions
01147        *  correspond to increasing bit positions (see the main class notes for
01148        *  an example).
01149        */
01150       template<class _CharT, class _Traits, class _Alloc>
01151     std::basic_string<_CharT, _Traits, _Alloc>
01152     to_string() const
01153     {
01154       std::basic_string<_CharT, _Traits, _Alloc> __result;
01155       _M_copy_to_string(__result, _CharT('0'), _CharT('1'));
01156       return __result;
01157     }
01158 
01159       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01160       // 396. what are characters zero and one.
01161       template<class _CharT, class _Traits, class _Alloc>
01162     std::basic_string<_CharT, _Traits, _Alloc>
01163     to_string(_CharT __zero, _CharT __one = _CharT('1')) const
01164     {
01165       std::basic_string<_CharT, _Traits, _Alloc> __result;
01166       _M_copy_to_string(__result, __zero, __one);
01167       return __result;
01168     }
01169 
01170       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01171       // 434. bitset::to_string() hard to use.
01172       template<class _CharT, class _Traits>
01173     std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
01174     to_string() const
01175     { return to_string<_CharT, _Traits, std::allocator<_CharT> >(); }
01176 
01177       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01178       // 853. to_string needs updating with zero and one.
01179       template<class _CharT, class _Traits>
01180     std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
01181     to_string(_CharT __zero, _CharT __one = _CharT('1')) const
01182     { return to_string<_CharT, _Traits,
01183                        std::allocator<_CharT> >(__zero, __one); }
01184 
01185       template<class _CharT>
01186     std::basic_string<_CharT, std::char_traits<_CharT>,
01187                       std::allocator<_CharT> >
01188     to_string() const
01189     {
01190       return to_string<_CharT, std::char_traits<_CharT>,
01191                        std::allocator<_CharT> >();
01192     }
01193 
01194       template<class _CharT>
01195     std::basic_string<_CharT, std::char_traits<_CharT>,
01196                       std::allocator<_CharT> >
01197     to_string(_CharT __zero, _CharT __one = _CharT('1')) const
01198     {
01199       return to_string<_CharT, std::char_traits<_CharT>,
01200                        std::allocator<_CharT> >(__zero, __one);
01201     }
01202 
01203       std::basic_string<char, std::char_traits<char>, std::allocator<char> >
01204       to_string() const
01205       {
01206     return to_string<char, std::char_traits<char>,
01207                      std::allocator<char> >();
01208       }
01209 
01210       std::basic_string<char, std::char_traits<char>, std::allocator<char> >
01211       to_string(char __zero, char __one = '1') const
01212       {
01213     return to_string<char, std::char_traits<char>,
01214                      std::allocator<char> >(__zero, __one);
01215       }
01216 
01217       // Helper functions for string operations.
01218       template<class _CharT, class _Traits>
01219         void
01220         _M_copy_from_ptr(const _CharT*, size_t, size_t, size_t,
01221              _CharT, _CharT);
01222 
01223       template<class _CharT, class _Traits, class _Alloc>
01224     void
01225     _M_copy_from_string(const std::basic_string<_CharT,
01226                 _Traits, _Alloc>& __s, size_t __pos, size_t __n,
01227                 _CharT __zero, _CharT __one)
01228     { _M_copy_from_ptr<_CharT, _Traits>(__s.data(), __s.size(), __pos, __n,
01229                         __zero, __one); }
01230 
01231       template<class _CharT, class _Traits, class _Alloc>
01232     void
01233         _M_copy_to_string(std::basic_string<_CharT, _Traits, _Alloc>&,
01234               _CharT, _CharT) const;
01235 
01236       // NB: Backward compat.
01237       template<class _CharT, class _Traits, class _Alloc>
01238     void
01239     _M_copy_from_string(const std::basic_string<_CharT,
01240                 _Traits, _Alloc>& __s, size_t __pos, size_t __n)
01241     { _M_copy_from_string(__s, __pos, __n, _CharT('0'), _CharT('1')); }
01242 
01243       template<class _CharT, class _Traits, class _Alloc>
01244     void
01245         _M_copy_to_string(std::basic_string<_CharT, _Traits,_Alloc>& __s) const
01246     { _M_copy_to_string(__s, _CharT('0'), _CharT('1')); }
01247 
01248       /// Returns the number of bits which are set.
01249       size_t
01250       count() const
01251       { return this->_M_do_count(); }
01252 
01253       /// Returns the total number of bits.
01254       _GLIBCXX_CONSTEXPR size_t
01255       size() const
01256       { return _Nb; }
01257 
01258       //@{
01259       /// These comparisons for equality/inequality are, well, @e bitwise.
01260       bool
01261       operator==(const bitset<_Nb>& __rhs) const
01262       { return this->_M_is_equal(__rhs); }
01263 
01264       bool
01265       operator!=(const bitset<_Nb>& __rhs) const
01266       { return !this->_M_is_equal(__rhs); }
01267       //@}
01268       
01269       /**
01270        *  @brief Tests the value of a bit.
01271        *  @param  position  The index of a bit.
01272        *  @return  The value at @a pos.
01273        *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
01274        */
01275       bool
01276       test(size_t __position) const
01277       {
01278     if (__position >= _Nb)
01279       __throw_out_of_range(__N("bitset::test"));
01280     return _Unchecked_test(__position);
01281       }
01282 
01283       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01284       // DR 693. std::bitset::all() missing.
01285       /**
01286        *  @brief Tests whether all the bits are on.
01287        *  @return  True if all the bits are set.
01288        */
01289       bool
01290       all() const
01291       { return this->_M_are_all_aux() == _Nb; }
01292 
01293       /**
01294        *  @brief Tests whether any of the bits are on.
01295        *  @return  True if at least one bit is set.
01296        */
01297       bool
01298       any() const
01299       { return this->_M_is_any(); }
01300 
01301       /**
01302        *  @brief Tests whether any of the bits are on.
01303        *  @return  True if none of the bits are set.
01304        */
01305       bool
01306       none() const
01307       { return !this->_M_is_any(); }
01308 
01309       //@{
01310       /// Self-explanatory.
01311       bitset<_Nb>
01312       operator<<(size_t __position) const
01313       { return bitset<_Nb>(*this) <<= __position; }
01314 
01315       bitset<_Nb>
01316       operator>>(size_t __position) const
01317       { return bitset<_Nb>(*this) >>= __position; }
01318       //@}
01319       
01320       /**
01321        *  @brief  Finds the index of the first "on" bit.
01322        *  @return  The index of the first bit set, or size() if not found.
01323        *  @ingroup SGIextensions
01324        *  @sa  _Find_next
01325        */
01326       size_t
01327       _Find_first() const
01328       { return this->_M_do_find_first(_Nb); }
01329 
01330       /**
01331        *  @brief  Finds the index of the next "on" bit after prev.
01332        *  @return  The index of the next bit set, or size() if not found.
01333        *  @param  prev  Where to start searching.
01334        *  @ingroup SGIextensions
01335        *  @sa  _Find_first
01336        */
01337       size_t
01338       _Find_next(size_t __prev ) const
01339       { return this->_M_do_find_next(__prev, _Nb); }
01340     };
01341 
01342   // Definitions of non-inline member functions.
01343   template<size_t _Nb>
01344     template<class _CharT, class _Traits>
01345       void
01346       bitset<_Nb>::
01347       _M_copy_from_ptr(const _CharT* __s, size_t __len,
01348                size_t __pos, size_t __n, _CharT __zero, _CharT __one)
01349       {
01350     reset();
01351     const size_t __nbits = std::min(_Nb, std::min(__n, __len - __pos));
01352     for (size_t __i = __nbits; __i > 0; --__i)
01353       {
01354         const _CharT __c = __s[__pos + __nbits - __i];
01355         if (_Traits::eq(__c, __zero))
01356           ;
01357         else if (_Traits::eq(__c, __one))
01358           _Unchecked_set(__i - 1);
01359         else
01360           __throw_invalid_argument(__N("bitset::_M_copy_from_ptr"));
01361       }
01362       }
01363 
01364   template<size_t _Nb>
01365     template<class _CharT, class _Traits, class _Alloc>
01366       void
01367       bitset<_Nb>::
01368       _M_copy_to_string(std::basic_string<_CharT, _Traits, _Alloc>& __s,
01369             _CharT __zero, _CharT __one) const
01370       {
01371     __s.assign(_Nb, __zero);
01372     for (size_t __i = _Nb; __i > 0; --__i)
01373       if (_Unchecked_test(__i - 1))
01374         _Traits::assign(__s[_Nb - __i], __one);
01375       }
01376 
01377   // 23.3.5.3 bitset operations:
01378   //@{
01379   /**
01380    *  @brief  Global bitwise operations on bitsets.
01381    *  @param  x  A bitset.
01382    *  @param  y  A bitset of the same size as @a x.
01383    *  @return  A new bitset.
01384    *
01385    *  These should be self-explanatory.
01386   */
01387   template<size_t _Nb>
01388     inline bitset<_Nb>
01389     operator&(const bitset<_Nb>& __x, const bitset<_Nb>& __y)
01390     {
01391       bitset<_Nb> __result(__x);
01392       __result &= __y;
01393       return __result;
01394     }
01395 
01396   template<size_t _Nb>
01397     inline bitset<_Nb>
01398     operator|(const bitset<_Nb>& __x, const bitset<_Nb>& __y)
01399     {
01400       bitset<_Nb> __result(__x);
01401       __result |= __y;
01402       return __result;
01403     }
01404 
01405   template <size_t _Nb>
01406     inline bitset<_Nb>
01407     operator^(const bitset<_Nb>& __x, const bitset<_Nb>& __y)
01408     {
01409       bitset<_Nb> __result(__x);
01410       __result ^= __y;
01411       return __result;
01412     }
01413   //@}
01414 
01415   //@{
01416   /**
01417    *  @brief Global I/O operators for bitsets.
01418    *
01419    *  Direct I/O between streams and bitsets is supported.  Output is
01420    *  straightforward.  Input will skip whitespace, only accept @a 0 and @a 1
01421    *  characters, and will only extract as many digits as the %bitset will
01422    *  hold.
01423   */
01424   template<class _CharT, class _Traits, size_t _Nb>
01425     std::basic_istream<_CharT, _Traits>&
01426     operator>>(std::basic_istream<_CharT, _Traits>& __is, bitset<_Nb>& __x)
01427     {
01428       typedef typename _Traits::char_type          char_type;
01429       typedef std::basic_istream<_CharT, _Traits>  __istream_type;
01430       typedef typename __istream_type::ios_base    __ios_base;
01431 
01432       std::basic_string<_CharT, _Traits> __tmp;
01433       __tmp.reserve(_Nb);
01434 
01435       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01436       // 303. Bitset input operator underspecified
01437       const char_type __zero = __is.widen('0');
01438       const char_type __one = __is.widen('1');
01439 
01440       typename __ios_base::iostate __state = __ios_base::goodbit;
01441       typename __istream_type::sentry __sentry(__is);
01442       if (__sentry)
01443     {
01444       __try
01445         {
01446           for (size_t __i = _Nb; __i > 0; --__i)
01447         {
01448           static typename _Traits::int_type __eof = _Traits::eof();
01449           
01450           typename _Traits::int_type __c1 = __is.rdbuf()->sbumpc();
01451           if (_Traits::eq_int_type(__c1, __eof))
01452             {
01453               __state |= __ios_base::eofbit;
01454               break;
01455             }
01456           else
01457             {
01458               const char_type __c2 = _Traits::to_char_type(__c1);
01459               if (_Traits::eq(__c2, __zero))
01460             __tmp.push_back(__zero);
01461               else if (_Traits::eq(__c2, __one))
01462             __tmp.push_back(__one);
01463               else if (_Traits::
01464                    eq_int_type(__is.rdbuf()->sputbackc(__c2),
01465                        __eof))
01466             {
01467               __state |= __ios_base::failbit;
01468               break;
01469             }
01470             }
01471         }
01472         }
01473       __catch(__cxxabiv1::__forced_unwind&)
01474         {
01475           __is._M_setstate(__ios_base::badbit);     
01476           __throw_exception_again;
01477         }
01478       __catch(...)
01479         { __is._M_setstate(__ios_base::badbit); }
01480     }
01481 
01482       if (__tmp.empty() && _Nb)
01483     __state |= __ios_base::failbit;
01484       else
01485     __x._M_copy_from_string(__tmp, static_cast<size_t>(0), _Nb,
01486                 __zero, __one);
01487       if (__state)
01488     __is.setstate(__state);
01489       return __is;
01490     }
01491 
01492   template <class _CharT, class _Traits, size_t _Nb>
01493     std::basic_ostream<_CharT, _Traits>&
01494     operator<<(std::basic_ostream<_CharT, _Traits>& __os,
01495            const bitset<_Nb>& __x)
01496     {
01497       std::basic_string<_CharT, _Traits> __tmp;
01498 
01499       // _GLIBCXX_RESOLVE_LIB_DEFECTS
01500       // 396. what are characters zero and one.
01501       const ctype<_CharT>& __ct = use_facet<ctype<_CharT> >(__os.getloc());
01502       __x._M_copy_to_string(__tmp, __ct.widen('0'), __ct.widen('1'));
01503       return __os << __tmp;
01504     }
01505   //@}
01506 
01507 _GLIBCXX_END_NAMESPACE_CONTAINER
01508 } // namespace std
01509 
01510 #undef _GLIBCXX_BITSET_WORDS
01511 #undef _GLIBCXX_BITSET_BITS_PER_WORD
01512 
01513 #ifdef __GXX_EXPERIMENTAL_CXX0X__
01514 
01515 #include <bits/functional_hash.h>
01516 
01517 namespace std _GLIBCXX_VISIBILITY(default)
01518 {
01519 _GLIBCXX_BEGIN_NAMESPACE_VERSION
01520 
01521   // DR 1182.
01522   /// std::hash specialization for bitset.
01523   template<size_t _Nb>
01524     struct hash<_GLIBCXX_STD_C::bitset<_Nb>>
01525     : public __hash_base<size_t, _GLIBCXX_STD_C::bitset<_Nb>>
01526     {
01527       size_t
01528       operator()(const _GLIBCXX_STD_C::bitset<_Nb>& __b) const
01529       {
01530     const size_t __clength = (_Nb + __CHAR_BIT__ - 1) / __CHAR_BIT__;
01531     return std::_Hash_impl::hash(__b._M_getdata(), __clength);
01532       }
01533     };
01534 
01535   template<>
01536     struct hash<_GLIBCXX_STD_C::bitset<0>>
01537     : public __hash_base<size_t, _GLIBCXX_STD_C::bitset<0>>
01538     {
01539       size_t
01540       operator()(const _GLIBCXX_STD_C::bitset<0>&) const
01541       { return 0; }
01542     };
01543 
01544 _GLIBCXX_END_NAMESPACE_VERSION
01545 } // namespace
01546 
01547 #endif // __GXX_EXPERIMENTAL_CXX0X__
01548 
01549 #ifdef _GLIBCXX_DEBUG
01550 # include <debug/bitset>
01551 #endif
01552 
01553 #ifdef _GLIBCXX_PROFILE
01554 # include <profile/bitset>
01555 #endif
01556 
01557 #endif /* _GLIBCXX_BITSET */