问题标题: @刘小川

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蒋祖轩
蒋祖轩
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istream:

// Input streams -*- C++ -*-

// Copyright (C) 1997-2014 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 3, 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

//
// ISO C++ 14882: 27.6.1  Input streams
//

/** @file include/istream
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_ISTREAM
#define _GLIBCXX_ISTREAM 1

#pragma GCC system_header

#include <ios>
#include <ostream>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**
   *  @brief  Template class basic_istream.
   *  @ingroup io
   *
   *  @tparam _CharT  Type of character stream.
   *  @tparam _Traits  Traits for character type, defaults to
   *                   char_traits<_CharT>.
   *
   *  This is the base class for all input streams.  It provides text
   *  formatting of all builtin types, and communicates with any class
   *  derived from basic_streambuf to do the actual input.
  */
  template<typename _CharT, typename _Traits>
    class basic_istream : virtual public basic_ios<_CharT, _Traits>
    {
    public:
      // Types (inherited from basic_ios (27.4.4)):
      typedef _CharT                    char_type;
      typedef typename _Traits::int_type        int_type;
      typedef typename _Traits::pos_type        pos_type;
      typedef typename _Traits::off_type        off_type;
      typedef _Traits                   traits_type;

      // Non-standard Types:
      typedef basic_streambuf<_CharT, _Traits>        __streambuf_type;
      typedef basic_ios<_CharT, _Traits>      __ios_type;
      typedef basic_istream<_CharT, _Traits>      __istream_type;
      typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
                            __num_get_type;
      typedef ctype<_CharT>                   __ctype_type;

    protected:
      // Data Members:
      /**
       *  The number of characters extracted in the previous unformatted
       *  function; see gcount().
      */
      streamsize        _M_gcount;

    public:
      /**
       *  @brief  Base constructor.
       *
       *  This ctor is almost never called by the user directly, rather from
       *  derived classes' initialization lists, which pass a pointer to
       *  their own stream buffer.
      */
      explicit
      basic_istream(__streambuf_type* __sb)
      : _M_gcount(streamsize(0))
      { this->init(__sb); }

      /**
       *  @brief  Base destructor.
       *
       *  This does very little apart from providing a virtual base dtor.
      */
      virtual
      ~basic_istream()
      { _M_gcount = streamsize(0); }

      /// Safe prefix/suffix operations.
      class sentry;
      friend class sentry;

      //@{
      /**
       *  @brief  Interface for manipulators.
       *
       *  Manipulators such as @c std::ws and @c std::dec use these
       *  functions in constructs like
       *  <code>std::cin >> std::ws</code>.
       *  For more information, see the iomanip header.
      */
      __istream_type&
      operator>>(__istream_type& (*__pf)(__istream_type&))
      { return __pf(*this); }

      __istream_type&
      operator>>(__ios_type& (*__pf)(__ios_type&))
      {
    __pf(*this);
    return *this;
      }

      __istream_type&
      operator>>(ios_base& (*__pf)(ios_base&))
      {
    __pf(*this);
    return *this;
      }
      //@}

      //@{
      /**
       *  @name Extractors
       *
       *  All the @c operator>> functions (aka <em>formatted input
       *  functions</em>) have some common behavior.  Each starts by
       *  constructing a temporary object of type std::basic_istream::sentry
       *  with the second argument (noskipws) set to false.  This has several
       *  effects, concluding with the setting of a status flag; see the
       *  sentry **ation for more.
       *
       *  If the sentry status is good, the function tries to extract
       *  whatever data is appropriate for the type of the argument.
       *
       *  If an exception is thrown during extraction, ios_base::badbit
       *  will be turned on in the stream's error state without causing an
       *  ios_base::failure to be thrown.  The original exception will then
       *  be rethrown.
      */

      //@{
      /**
       *  @brief  Integer arithmetic extractors
       *  @param  __n A variable of builtin integral type.
       *  @return  @c *this if successful
       *
       *  These functions use the stream's current locale (specifically, the
       *  @c num_get facet) to parse the input data.
      */
      __istream_type&
      operator>>(bool& __n)
      { return _M_extract(__n); }

      __istream_type&
      operator>>(short& __n);

      __istream_type&
      operator>>(unsigned short& __n)
      { return _M_extract(__n); }

      __istream_type&
      operator>>(int& __n);

      __istream_type&
      operator>>(unsigned int& __n)
      { return _M_extract(__n); }

      __istream_type&
      operator>>(long& __n)
      { return _M_extract(__n); }

      __istream_type&
      operator>>(unsigned long& __n)
      { return _M_extract(__n); }

#ifdef _GLIBCXX_USE_LONG_LONG
      __istream_type&
      operator>>(long long& __n)
      { return _M_extract(__n); }

      __istream_type&
      operator>>(unsigned long long& __n)
      { return _M_extract(__n); }
#endif
      //@}

      //@{
      /**
       *  @brief  Floating point arithmetic extractors
       *  @param  __f A variable of builtin floating point type.
       *  @return  @c *this if successful
       *
       *  These functions use the stream's current locale (specifically, the
       *  @c num_get facet) to parse the input data.
      */
      __istream_type&
      operator>>(float& __f)
      { return _M_extract(__f); }

      __istream_type&
      operator>>(double& __f)
      { return _M_extract(__f); }

      __istream_type&
      operator>>(long double& __f)
      { return _M_extract(__f); }
      //@}

      /**
       *  @brief  Basic arithmetic extractors
       *  @param  __p A variable of pointer type.
       *  @return  @c *this if successful
       *
       *  These functions use the stream's current locale (specifically, the
       *  @c num_get facet) to parse the input data.
      */
      __istream_type&
      operator>>(void*& __p)
      { return _M_extract(__p); }

      /**
       *  @brief  Extracting into another streambuf.
       *  @param  __sb  A pointer to a streambuf
       *
       *  This function behaves like one of the basic arithmetic extractors,
       *  in that it also constructs a sentry object and has the same error
       *  handling behavior.
       *
       *  If @p __sb is NULL, the stream will set failbit in its error state.
       *
       *  Characters are extracted from this stream and inserted into the
       *  @p __sb streambuf until one of the following occurs:
       *
       *  - the input stream reaches end-of-file,
       *  - insertion into the output buffer fails (in this case, the
       *    character that would have been inserted is not extracted), or
       *  - an exception occurs (and in this case is caught)
       *
       *  If the function inserts no characters, failbit is set.
      */
      __istream_type&
      operator>>(__streambuf_type* __sb);
      //@}

      // [27.6.1.3] unformatted input
      /**
       *  @brief  Character counting
       *  @return  The number of characters extracted by the previous
       *           unformatted input function dispatched for this stream.
      */
      streamsize
      gcount() const
      { return _M_gcount; }

      //@{
      /**
       *  @name Unformatted Input Functions
       *
       *  All the unformatted input functions have some common behavior.
       *  Each starts by constructing a temporary object of type
       *  std::basic_istream::sentry with the second argument (noskipws)
       *  set to true.  This has several effects, concluding with the
       *  setting of a status flag; see the sentry **ation for more.
       *
       *  If the sentry status is good, the function tries to extract
       *  whatever data is appropriate for the type of the argument.
       *
       *  The number of characters extracted is stored for later retrieval
       *  by gcount().
       *
       *  If an exception is thrown during extraction, ios_base::badbit
       *  will be turned on in the stream's error state without causing an
       *  ios_base::failure to be thrown.  The original exception will then
       *  be rethrown.
      */

      /**
       *  @brief  Simple extraction.
       *  @return  A character, or eof().
       *
       *  Tries to extract a character.  If none are available, sets failbit
       *  and returns traits::eof().
      */
      int_type
      get();

      /**
       *  @brief  Simple extraction.
       *  @param  __c  The character in which to store data.
       *  @return  *this
       *
       *  Tries to extract a character and store it in @a __c.  If none are
       *  available, sets failbit and returns traits::eof().
       *
       *  @note  This function is not overloaded on signed char and
       *         unsigned char.
      */
      __istream_type&
      get(char_type& __c);

      /**
       *  @brief  Simple multiple-character extraction.
       *  @param  __s  Pointer to an array.
       *  @param  __n  Maximum number of characters to store in @a __s.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Characters are extracted and stored into @a __s until one of the
       *  following happens:
       *
       *  - @c __n-1 characters are stored
       *  - the input sequence reaches EOF
       *  - the next character equals @a __delim, in which case the character
       *    is not extracted
       *
       * If no characters are stored, failbit is set in the stream's error
       * state.
       *
       * In any case, a null character is stored into the next location in
       * the array.
       *
       *  @note  This function is not overloaded on signed char and
       *         unsigned char.
      */
      __istream_type&
      get(char_type* __s, streamsize __n, char_type __delim);

      /**
       *  @brief  Simple multiple-character extraction.
       *  @param  __s  Pointer to an array.
       *  @param  __n  Maximum number of characters to store in @a s.
       *  @return  *this
       *
       *  Returns @c get(__s,__n,widen(&apos;\\n&apos;)).
      */
      __istream_type&
      get(char_type* __s, streamsize __n)
      { return this->get(__s, __n, this->widen('\n')); }

      /**
       *  @brief  Extraction into another streambuf.
       *  @param  __sb  A streambuf in which to store data.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Characters are extracted and inserted into @a __sb until one of the
       *  following happens:
       *
       *  - the input sequence reaches EOF
       *  - insertion into the output buffer fails (in this case, the
       *    character that would have been inserted is not extracted)
       *  - the next character equals @a __delim (in this case, the character
       *    is not extracted)
       *  - an exception occurs (and in this case is caught)
       *
       * If no characters are stored, failbit is set in the stream's error
       * state.
      */
      __istream_type&
      get(__streambuf_type& __sb, char_type __delim);

      /**
       *  @brief  Extraction into another streambuf.
       *  @param  __sb  A streambuf in which to store data.
       *  @return  *this
       *
       *  Returns @c get(__sb,widen(&apos;\\n&apos;)).
      */
      __istream_type&
      get(__streambuf_type& __sb)
      { return this->get(__sb, this->widen('\n')); }

      /**
       *  @brief  String extraction.
       *  @param  __s  A character array in which to store the data.
       *  @param  __n  Maximum number of characters to extract.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Extracts and stores characters into @a __s until one of the
       *  following happens.  Note that these criteria are required to be
       *  tested in the order listed here, to allow an input line to exactly
       *  fill the @a __s array without setting failbit.
       *
       *  -# the input sequence reaches end-of-file, in which case eofbit
       *     is set in the stream error state
       *  -# the next character equals @c __delim, in which case the character
       *     is extracted (and therefore counted in @c gcount()) but not stored
       *  -# @c __n-1 characters are stored, in which case failbit is set
       *     in the stream error state
       *
       *  If no characters are extracted, failbit is set.  (An empty line of
       *  input should therefore not cause failbit to be set.)
       *
       *  In any case, a null character is stored in the next location in
       *  the array.
      */
      __istream_type&
      getline(char_type* __s, streamsize __n, char_type __delim);

      /**
       *  @brief  String extraction.
       *  @param  __s  A character array in which to store the data.
       *  @param  __n  Maximum number of characters to extract.
       *  @return  *this
       *
       *  Returns @c getline(__s,__n,widen(&apos;\\n&apos;)).
      */
      __istream_type&
      getline(char_type* __s, streamsize __n)
      { return this->getline(__s, __n, this->widen('\n')); }

      /**
       *  @brief  Discarding characters
       *  @param  __n  Number of characters to discard.
       *  @param  __delim  A "stop" character.
       *  @return  *this
       *
       *  Extracts characters and throws them away until one of the
       *  following happens:
       *  - if @a __n @c != @c std::numeric_limits<int>::max(), @a __n
       *    characters are extracted
       *  - the input sequence reaches end-of-file
       *  - the next character equals @a __delim (in this case, the character
       *    is extracted); note that this condition will never occur if
       *    @a __delim equals @c traits::eof().
       *
       *  NB: Provide three overloads, instead of the single function
       *  (with defaults) mandated by the Standard: this leads to a
       *  better performing implementation, while still conforming to
       *  the Standard.
      */
      __istream_type&
      ignore(streamsize __n, int_type __delim);

      __istream_type&
      ignore(streamsize __n);

      __istream_type&
      ignore();

      /**
       *  @brief  Looking ahead in the stream
       *  @return  The next character, or eof().
       *
       *  If, after constructing the sentry object, @c good() is false,
       *  returns @c traits::eof().  Otherwise reads but does not extract
       *  the next input character.
      */
      int_type
      peek();

      /**
       *  @brief  Extraction without delimiters.
       *  @param  __s  A character array.
       *  @param  __n  Maximum number of characters to store.
       *  @return  *this
       *
       *  If the stream state is @c good(), extracts characters and stores
       *  them into @a __s until one of the following happens:
       *  - @a __n characters are stored
       *  - the input sequence reaches end-of-file, in which case the error
       *    state is set to @c failbit|eofbit.
       *
       *  @note  This function is not overloaded on signed char and
       *         unsigned char.
      */
      __istream_type&
      read(char_type* __s, streamsize __n);

      /**
       *  @brief  Extraction until the buffer is exhausted, but no more.
       *  @param  __s  A character array.
       *  @param  __n  Maximum number of characters to store.
       *  @return  The number of characters extracted.
       *
       *  Extracts characters and stores them into @a __s depending on the
       *  number of characters remaining in the streambuf's buffer,
       *  @c rdbuf()->in_avail(), called @c A here:
       *  - if @c A @c == @c -1, sets eofbit and extracts no characters
       *  - if @c A @c == @c 0, extracts no characters
       *  - if @c A @c > @c 0, extracts @c min(A,n)
       *
       *  The goal is to empty the current buffer, and to not request any
       *  more from the external input sequence controlled by the streambuf.
      */
      streamsize
      readsome(char_type* __s, streamsize __n);

      /**
       *  @brief  Unextracting a single character.
       *  @param  __c  The character to push back into the input stream.
       *  @return  *this
       *
       *  If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c).
       *
       *  If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in
       *  the error state.
       *
       *  @note  This function first clears eofbit.  Since no characters
       *         are extracted, the next call to @c gcount() will return 0,
       *         as required by DR 60.
      */
      __istream_type&
      putback(char_type __c);

      /**
       *  @brief  Unextracting the previous character.
       *  @return  *this
       *
       *  If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c).
       *
       *  If @c rdbuf() is null or if @c sungetc() fails, sets badbit in
       *  the error state.
       *
       *  @note  This function first clears eofbit.  Since no characters
       *         are extracted, the next call to @c gcount() will return 0,
       *         as required by DR 60.
      */
      __istream_type&
      unget();

      /**
       *  @brief  Synchronizing the stream buffer.
       *  @return  0 on success, -1 on failure
       *
       *  If @c rdbuf() is a null pointer, returns -1.
       *
       *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
       *  sets badbit and returns -1.
       *
       *  Otherwise, returns 0.
       *
       *  @note  This function does not count the number of characters
       *         extracted, if any, and therefore does not affect the next
       *         call to @c gcount().
      */
      int
      sync();

      /**
       *  @brief  Getting the current read position.
       *  @return  A file position object.
       *
       *  If @c fail() is not false, returns @c pos_type(-1) to indicate
       *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,in).
       *
       *  @note  This function does not count the number of characters
       *         extracted, if any, and therefore does not affect the next
       *         call to @c gcount().  At variance with putback, unget and
       *         seekg, eofbit is not cleared first.
      */
      pos_type
      tellg();

      /**
       *  @brief  Changing the current read position.
       *  @param  __pos  A file position object.
       *  @return  *this
       *
       *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(__pos).  If
       *  that function fails, sets failbit.
       *
       *  @note  This function first clears eofbit.  It does not count the
       *         number of characters extracted, if any, and therefore does
       *         not affect the next call to @c gcount().
      */
      __istream_type&
      seekg(pos_type);

      /**
       *  @brief  Changing the current read position.
       *  @param  __off  A file offset object.
       *  @param  __dir  The direction in which to seek.
       *  @return  *this
       *
       *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(__off,__dir).
       *  If that function fails, sets failbit.
       *
       *  @note  This function first clears eofbit.  It does not count the
       *         number of characters extracted, if any, and therefore does
       *         not affect the next call to @c gcount().
      */
      __istream_type&
      seekg(off_type, ios_base::seekdir);
      //@}

    protected:
      basic_istream()
      : _M_gcount(streamsize(0))
      { this->init(0); }

      template<typename _ValueT>
    __istream_type&
    _M_extract(_ValueT& __v);
    };

  /// Explicit specialization declarations, defined in src/istream.cc.
  template<>
    basic_istream<char>&
    basic_istream<char>::
    getline(char_type* __s, streamsize __n, char_type __delim);

  template<>
    basic_istream<char>&
    basic_istream<char>::
    ignore(streamsize __n);

  template<>
    basic_istream<char>&
    basic_istream<char>::
    ignore(streamsize __n, int_type __delim);

#ifdef _GLIBCXX_USE_WCHAR_T
  template<>
    basic_istream<wchar_t>&
    basic_istream<wchar_t>::
    getline(char_type* __s, streamsize __n, char_type __delim);

  template<>
    basic_istream<wchar_t>&
    basic_istream<wchar_t>::
    ignore(streamsize __n);

  template<>
    basic_istream<wchar_t>&
    basic_istream<wchar_t>::
    ignore(streamsize __n, int_type __delim);
#endif

  /**
   *  @brief  Performs setup work for input streams.
   *
   *  Objects of this class are created before all of the standard
   *  extractors are run.  It is responsible for <em>exception-safe
   *  prefix and suffix operations,</em> although only prefix actions
   *  are currently required by the standard.
  */
  template<typename _CharT, typename _Traits>
    class basic_istream<_CharT, _Traits>::sentry
    {
      // Data Members.
      bool _M_ok;

    public:
      /// Easy access to dependent types.
      typedef _Traits                   traits_type;
      typedef basic_streambuf<_CharT, _Traits>        __streambuf_type;
      typedef basic_istream<_CharT, _Traits>      __istream_type;
      typedef typename __istream_type::__ctype_type     __ctype_type;
      typedef typename _Traits::int_type        __int_type;

      /**
       *  @brief  The constructor performs all the work.
       *  @param  __is  The input stream to guard.
       *  @param  __noskipws  Whether to consume whitespace or not.
       *
       *  If the stream state is good (@a __is.good() is true), then the
       *  following actions are performed, otherwise the sentry state
       *  is false (<em>not okay</em>) and failbit is set in the
       *  stream state.
       *
       *  The sentry's preparatory actions are:
       *
       *  -# if the stream is tied to an output stream, @c is.tie()->flush()
       *     is called to synchronize the output sequence
       *  -# if @a __noskipws is false, and @c ios_base::skipws is set in
       *     @c is.flags(), the sentry extracts and discards whitespace
       *     characters from the stream.  The currently imbued locale is
       *     used to determine whether each character is whitespace.
       *
       *  If the stream state is still good, then the sentry state becomes
       *  true (@a okay).
      */
      explicit
      sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false);

      /**
       *  @brief  Quick status checking.
       *  @return  The sentry state.
       *
       *  For ease of use, sentries may be converted to booleans.  The
       *  return value is that of the sentry state (true == okay).
      */
#if __cplusplus >= 201103L
      explicit
#endif
      operator bool() const
      { return _M_ok; }
    };

  //@{
  /**
   *  @brief  Character extractors
   *  @param  __in  An input stream.
   *  @param  __c  A character reference.
   *  @return  in
   *
   *  Behaves like one of the formatted arithmetic extractors described in
   *  std::basic_istream.  After constructing a sentry object with good
   *  status, this function extracts a character (if one is available) and
   *  stores it in @a __c.  Otherwise, sets failbit in the input stream.
  */
  template<typename _CharT, typename _Traits>
    basic_istream<_CharT, _Traits>&
    operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c);

  template<class _Traits>
    inline basic_istream<char, _Traits>&
    operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
    { return (__in >> reinterpret_cast<char&>(__c)); }

  template<class _Traits>
    inline basic_istream<char, _Traits>&
    operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
    { return (__in >> reinterpret_cast<char&>(__c)); }
  //@}

  //@{
  /**
   *  @brief  Character string extractors
   *  @param  __in  An input stream.
   *  @param  __s  A pointer to a character array.
   *  @return  __in
   *
   *  Behaves like one of the formatted arithmetic extractors described in
   *  std::basic_istream.  After constructing a sentry object with good
   *  status, this function extracts up to @c n characters and stores them
   *  into the array starting at @a __s.  @c n is defined as:
   *
   *  - if @c width() is greater than zero, @c n is width() otherwise
   *  - @c n is <em>the number of elements of the largest array of *
   *  - @c char_type that can store a terminating @c eos.</em>
   *  - [27.6.1.2.3]/6
   *
   *  Characters are extracted and stored until one of the following happens:
   *  - @c n-1 characters are stored
   *  - EOF is reached
   *  - the next character is whitespace according to the current locale
   *  - the next character is a null byte (i.e., @c charT() )
   *
   *  @c width(0) is then called for the input stream.
   *
   *  If no characters are extracted, sets failbit.
  */
  template<typename _CharT, typename _Traits>
    basic_istream<_CharT, _Traits>&
    operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s);

  // Explicit specialization declaration, defined in src/istream.cc.
  template<>
    basic_istream<char>&
    operator>>(basic_istream<char>& __in, char* __s);

  template<class _Traits>
    inline basic_istream<char, _Traits>&
    operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
    { return (__in >> reinterpret_cast<char*>(__s)); }

  template<class _Traits>
    inline basic_istream<char, _Traits>&
    operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
    { return (__in >> reinterpret_cast<char*>(__s)); }
  //@}

  /**
   *  @brief  Template class basic_iostream
   *  @ingroup io
   *
   *  @tparam _CharT  Type of character stream.
   *  @tparam _Traits  Traits for character type, defaults to
   *                   char_traits<_CharT>.
   *
   *  This class multiply inherits from the input and output stream classes
   *  simply to provide a single interface.
  */
  template<typename _CharT, typename _Traits>
    class basic_iostream
    : public basic_istream<_CharT, _Traits>,
      public basic_ostream<_CharT, _Traits>
    {
    public:
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 271. basic_iostream missing typedefs
      // Types (inherited):
      typedef _CharT                    char_type;
      typedef typename _Traits::int_type        int_type;
      typedef typename _Traits::pos_type        pos_type;
      typedef typename _Traits::off_type        off_type;
      typedef _Traits                   traits_type;

      // Non-standard Types:
      typedef basic_istream<_CharT, _Traits>      __istream_type;
      typedef basic_ostream<_CharT, _Traits>      __ostream_type;

      /**
       *  @brief  Constructor does nothing.
       *
       *  Both of the parent classes are initialized with the same
       *  streambuf pointer passed to this constructor.
      */
      explicit
      basic_iostream(basic_streambuf<_CharT, _Traits>* __sb)
      : __istream_type(__sb), __ostream_type(__sb) { }

      /**
       *  @brief  Destructor does nothing.
      */
      virtual
      ~basic_iostream() { }

    protected:
      basic_iostream()
      : __istream_type(), __ostream_type() { }
    };

  /**
   *  @brief  Quick and easy way to eat whitespace
   *
   *  This manipulator extracts whitespace characters, stopping when the
   *  next character is non-whitespace, or when the input sequence is empty.
   *  If the sequence is empty, @c eofbit is set in the stream, but not
   *  @c failbit.
   *
   *  The current locale is used to distinguish whitespace characters.
   *
   *  Example:
   *  @code
   *     MyClass   mc;
   *
   *     std::cin >> std::ws >> mc;
   *  @endcode
   *  will skip leading whitespace before calling operator>> on cin and your
   *  object.  Note that the same effect can be achieved by creating a
   *  std::basic_istream::sentry inside your definition of operator>>.
  */
  template<typename _CharT, typename _Traits>
    basic_istream<_CharT, _Traits>&
    ws(basic_istream<_CharT, _Traits>& __is);

#if __cplusplus >= 201103L
  // [27.7.1.6] Rvalue stream extraction
  /**
   *  @brief  Generic extractor for rvalue stream
   *  @param  __is  An input stream.
   *  @param  __x  A reference to the extraction target.
   *  @return  is
   *
   *  This is just a forwarding function to allow extraction from
   *  rvalue streams since they won't bind to the extractor functions
   *  that take an lvalue reference.
  */
  template<typename _CharT, typename _Traits, typename _Tp>
    inline basic_istream<_CharT, _Traits>&
    operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
    { return (__is >> __x); }
#endif // C++11

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#include <bits/istream.tcc>

#endif  /* _GLIBCXX_ISTREAM */

bitset:

// <bitset> -*- C++ -*-

// Copyright (C) 2001-2014 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 3, 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/*
 * Copyright (c) 1998
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its **ation 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 **ation.  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 include/bitset
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_BITSET
#define _GLIBCXX_BITSET 1

#pragma GCC system_header

#include <string>
#include <bits/functexcept.h>   // For invalid_argument, out_of_range,
                                // overflow_error
#include <iosfwd>
#include <bits/cxxabi_forced.h>

#define _GLIBCXX_BITSET_BITS_PER_WORD  (__CHAR_BIT__ * __SIZEOF_LONG__)
#define _GLIBCXX_BITSET_WORDS(__n) \
  ((__n) / _GLIBCXX_BITSET_BITS_PER_WORD + \
   ((__n) % _GLIBCXX_BITSET_BITS_PER_WORD == 0 ? 0 : 1))

#define _GLIBCXX_BITSET_BITS_PER_ULL (__CHAR_BIT__ * __SIZEOF_LONG_LONG__)

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_CONTAINER

  /**
   *  Base class, general case.  It is a class invariant that _Nw will be
   *  nonnegative.
   *
   *  See **ation for bitset.
  */
  template<size_t _Nw>
    struct _Base_bitset
    {
      typedef unsigned long _WordT;

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

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      : _M_w() { }

#if __cplusplus >= 201103L
      constexpr _Base_bitset(unsigned long long __val) noexcept
      : _M_w{ _WordT(__val)
#if __SIZEOF_LONG_LONG__ > __SIZEOF_LONG__
           , _WordT(__val >> _GLIBCXX_BITSET_BITS_PER_WORD)
#endif
       } { }
#else
      _Base_bitset(unsigned long __val)
      : _M_w()
      { _M_w[0] = __val; }
#endif

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

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

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

#if __cplusplus >= 201103L
      const _WordT*
      _M_getdata() const noexcept
      { return _M_w; }
#endif

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

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

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

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

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

      void
      _M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT;

      void
      _M_do_right_shift(size_t __shift) _GLIBCXX_NOEXCEPT;

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

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

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

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

      template<size_t _Nb>
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        {
      for (size_t __i = 0; __i < _Nw - 1; __i++)
        if (_M_w[__i] != ~static_cast<_WordT>(0))
          return false;
      return _M_hiword() == (~static_cast<_WordT>(0)
                 >> (_Nw * _GLIBCXX_BITSET_BITS_PER_WORD
                     - _Nb));
    }

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      {
    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 _GLIBCXX_NOEXCEPT
      {
    size_t __result = 0;
    for (size_t __i = 0; __i < _Nw; __i++)
      __result += __builtin_popcountl(_M_w[__i]);
    return __result;
      }

      unsigned long
      _M_do_to_ulong() const;

#if __cplusplus >= 201103L
      unsigned long long
      _M_do_to_ullong() const;
#endif

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

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

  // Definitions of non-inline functions from _Base_bitset.
  template<size_t _Nw>
    void
    _Base_bitset<_Nw>::_M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT
    {
      if (__builtin_expect(__shift != 0, 1))
    {
      const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
      const size_t __offset = __shift % _GLIBCXX_BITSET_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 = (_GLIBCXX_BITSET_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;
        }

      std::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) _GLIBCXX_NOEXCEPT
    {
      if (__builtin_expect(__shift != 0, 1))
    {
      const size_t __wshift = __shift / _GLIBCXX_BITSET_BITS_PER_WORD;
      const size_t __offset = __shift % _GLIBCXX_BITSET_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 = (_GLIBCXX_BITSET_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;
        }

      std::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])
      __throw_overflow_error(__N("_Base_bitset::_M_do_to_ulong"));
      return _M_w[0];
    }

#if __cplusplus >= 201103L
  template<size_t _Nw>
    unsigned long long
    _Base_bitset<_Nw>::_M_do_to_ullong() const
    {
      const bool __dw = sizeof(unsigned long long) > sizeof(unsigned long);
      for (size_t __i = 1 + __dw; __i < _Nw; ++__i)
    if (_M_w[__i])
      __throw_overflow_error(__N("_Base_bitset::_M_do_to_ullong"));

      if (__dw)
    return _M_w[0] + (static_cast<unsigned long long>(_M_w[1])
              << _GLIBCXX_BITSET_BITS_PER_WORD);
      return _M_w[0];
    }
#endif

  template<size_t _Nw>
    size_t
    _Base_bitset<_Nw>::
    _M_do_find_first(size_t __not_found) const _GLIBCXX_NOEXCEPT
    {
      for (size_t __i = 0; __i < _Nw; __i++)
    {
      _WordT __thisword = _M_w[__i];
      if (__thisword != static_cast<_WordT>(0))
        return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
            + __builtin_ctzl(__thisword));
    }
      // 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 _GLIBCXX_NOEXCEPT
    {
      // make bound inclusive
      ++__prev;

      // check out of bounds
      if (__prev >= _Nw * _GLIBCXX_BITSET_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))
    return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
        + __builtin_ctzl(__thisword));

      // check subsequent words
      __i++;
      for (; __i < _Nw; __i++)
    {
      __thisword = _M_w[__i];
      if (__thisword != static_cast<_WordT>(0))
        return (__i * _GLIBCXX_BITSET_BITS_PER_WORD
            + __builtin_ctzl(__thisword));
    }
      // not found, so return an indication of failure.
      return __not_found;
    } // end _M_do_find_next

  /**
   *  Base class, specialization for a single word.
   *
   *  See **ation for bitset.
  */
  template<>
    struct _Base_bitset<1>
    {
      typedef unsigned long _WordT;
      _WordT _M_w;

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      : _M_w(0)
      { }

#if __cplusplus >= 201103L
      constexpr _Base_bitset(unsigned long long __val) noexcept
#else
      _Base_bitset(unsigned long __val)
#endif
      : _M_w(__val)
      { }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

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

      _GLIBCXX_CONSTEXPR _WordT
      _M_getword(size_t) const _GLIBCXX_NOEXCEPT
      { return _M_w; }

#if __cplusplus >= 201103L
      const _WordT*
      _M_getdata() const noexcept
      { return &_M_w; }
#endif

      _WordT&
      _M_hiword() _GLIBCXX_NOEXCEPT
      { return _M_w; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_hiword() const _GLIBCXX_NOEXCEPT
      { return _M_w; }

      void
      _M_do_and(const _Base_bitset<1>& __x) _GLIBCXX_NOEXCEPT
      { _M_w &= __x._M_w; }

      void
      _M_do_or(const _Base_bitset<1>& __x) _GLIBCXX_NOEXCEPT
      { _M_w |= __x._M_w; }

      void
      _M_do_xor(const _Base_bitset<1>& __x) _GLIBCXX_NOEXCEPT
      { _M_w ^= __x._M_w; }

      void
      _M_do_left_shift(size_t __shift) _GLIBCXX_NOEXCEPT
      { _M_w <<= __shift; }

      void
      _M_do_right_shift(size_t __shift) _GLIBCXX_NOEXCEPT
      { _M_w >>= __shift; }

      void
      _M_do_flip() _GLIBCXX_NOEXCEPT
      { _M_w = ~_M_w; }

      void
      _M_do_set() _GLIBCXX_NOEXCEPT
      { _M_w = ~static_cast<_WordT>(0); }

      void
      _M_do_reset() _GLIBCXX_NOEXCEPT
      { _M_w = 0; }

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

      template<size_t _Nb>
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        { return _M_w == (~static_cast<_WordT>(0)
              >> (_GLIBCXX_BITSET_BITS_PER_WORD - _Nb)); }

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      { return _M_w != 0; }

      size_t
      _M_do_count() const _GLIBCXX_NOEXCEPT
      { return __builtin_popcountl(_M_w); }

      unsigned long
      _M_do_to_ulong() const _GLIBCXX_NOEXCEPT
      { return _M_w; }

#if __cplusplus >= 201103L
      unsigned long long
      _M_do_to_ullong() const noexcept
      { return _M_w; }
#endif

      size_t
      _M_do_find_first(size_t __not_found) const _GLIBCXX_NOEXCEPT
      {
        if (_M_w != 0)
          return __builtin_ctzl(_M_w);
        else
          return __not_found;
      }

      // find the next "on" bit that follows "prev"
      size_t
      _M_do_find_next(size_t __prev, size_t __not_found) const
    _GLIBCXX_NOEXCEPT
      {
    ++__prev;
    if (__prev >= ((size_t) _GLIBCXX_BITSET_BITS_PER_WORD))
      return __not_found;

    _WordT __x = _M_w >> __prev;
    if (__x != 0)
      return __builtin_ctzl(__x) + __prev;
    else
      return __not_found;
      }
    };

  /**
   *  Base class, specialization for no storage (zero-length %bitset).
   *
   *  See **ation for bitset.
  */
  template<>
    struct _Base_bitset<0>
    {
      typedef unsigned long _WordT;

      _GLIBCXX_CONSTEXPR _Base_bitset() _GLIBCXX_NOEXCEPT
      { }

#if __cplusplus >= 201103L
      constexpr _Base_bitset(unsigned long long) noexcept
#else
      _Base_bitset(unsigned long)
#endif
      { }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichword(size_t __pos) _GLIBCXX_NOEXCEPT
      { return __pos / _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbyte(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (__pos % _GLIBCXX_BITSET_BITS_PER_WORD) / __CHAR_BIT__; }

      static _GLIBCXX_CONSTEXPR size_t
      _S_whichbit(size_t __pos) _GLIBCXX_NOEXCEPT
      {  return __pos % _GLIBCXX_BITSET_BITS_PER_WORD; }

      static _GLIBCXX_CONSTEXPR _WordT
      _S_maskbit(size_t __pos) _GLIBCXX_NOEXCEPT
      { return (static_cast<_WordT>(1)) << _S_whichbit(__pos); }

      // This would normally give access to the data.  The bounds-checking
      // in the bitset class will prevent the user from getting this far,
      // but (1) it must still return an lvalue to compile, and (2) the
      // user might call _Unchecked_set directly, in which case this /needs/
      // to fail.  Let's not penalize zero-length users unless they actually
      // make an unchecked call; all the memory ugliness is therefore
      // localized to this single should-never-get-this-far function.
      _WordT&
      _M_getword(size_t) _GLIBCXX_NOEXCEPT
      {
    __throw_out_of_range(__N("_Base_bitset::_M_getword")); 
    return *new _WordT;
      }

      _GLIBCXX_CONSTEXPR _WordT
      _M_getword(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return 0; }

      _GLIBCXX_CONSTEXPR _WordT
      _M_hiword() const _GLIBCXX_NOEXCEPT
      { return 0; }

      void
      _M_do_and(const _Base_bitset<0>&) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_or(const _Base_bitset<0>&) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_xor(const _Base_bitset<0>&) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_left_shift(size_t) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_right_shift(size_t) _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_flip() _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_set() _GLIBCXX_NOEXCEPT
      { }

      void
      _M_do_reset() _GLIBCXX_NOEXCEPT
      { }

      // Are all empty bitsets equal to each other?  Are they equal to
      // themselves?  How to compare a thing which has no state?  What is
      // the sound of one zero-length bitset clapping?
      bool
      _M_is_equal(const _Base_bitset<0>&) const _GLIBCXX_NOEXCEPT
      { return true; }

      template<size_t _Nb>
        bool
        _M_are_all() const _GLIBCXX_NOEXCEPT
        { return true; }

      bool
      _M_is_any() const _GLIBCXX_NOEXCEPT
      { return false; }

      size_t
      _M_do_count() const _GLIBCXX_NOEXCEPT
      { return 0; }

      unsigned long
      _M_do_to_ulong() const _GLIBCXX_NOEXCEPT
      { return 0; }

#if __cplusplus >= 201103L
      unsigned long long
      _M_do_to_ullong() const noexcept
      { return 0; }
#endif

      // Normally "not found" is the size, but that could also be
      // misinterpreted as an index in this corner case.  Oh well.
      size_t
      _M_do_find_first(size_t) const _GLIBCXX_NOEXCEPT
      { return 0; }

      size_t
      _M_do_find_next(size_t, size_t) const _GLIBCXX_NOEXCEPT
      { return 0; }
    };


  // Helper class to zero out the unused high-order bits in the highest word.
  template<size_t _Extrabits>
    struct _Sanitize
    {
      typedef unsigned long _WordT;

      static void
      _S_do_sanitize(_WordT& __val) _GLIBCXX_NOEXCEPT
      { __val &= ~((~static_cast<_WordT>(0)) << _Extrabits); }
    };

  template<>
    struct _Sanitize<0>
    {
      typedef unsigned long _WordT;

      static void
      _S_do_sanitize(_WordT) _GLIBCXX_NOEXCEPT { } 
    };

#if __cplusplus >= 201103L
  template<size_t _Nb, bool = _Nb < _GLIBCXX_BITSET_BITS_PER_ULL>
    struct _Sanitize_val
    {
      static constexpr unsigned long long
      _S_do_sanitize_val(unsigned long long __val)
      { return __val; }
    };

  template<size_t _Nb>
    struct _Sanitize_val<_Nb, true>
    {
      static constexpr unsigned long long
      _S_do_sanitize_val(unsigned long long __val)
      { return __val & ~((~static_cast<unsigned long long>(0)) << _Nb); }
    };
#endif

  /**
   *  The %bitset class represents a @e fixed-size sequence of bits.
   *
   *  @ingroup containers
   *
   *  (Note that %bitset does @e not meet the formal requirements of a
   *  <a href="tables.html#65">container</a>.  Mainly, it lacks iterators.)
   *
   *  The template argument, @a Nb, may be any non-negative number,
   *  specifying the number of bits (e.g., "0", "12", "1024*1024").
   *
   *  In the general unoptimized case, storage is allocated in word-sized
   *  blocks.  Let B be the number of bits in a word, then (Nb+(B-1))/B
   *  words will be used for storage.  B - Nb%B bits are unused.  (They are
   *  the high-order bits in the highest word.)  It is a class invariant
   *  that those unused bits are always zero.
   *
   *  If you think of %bitset as <em>a simple array of bits</em>, be
   *  aware that your mental picture is reversed: a %bitset behaves
   *  the same way as bits in integers do, with the bit at index 0 in
   *  the <em>least significant / right-hand</em> position, and the bit at
   *  index Nb-1 in the <em>most significant / left-hand</em> position.
   *  Thus, unlike other containers, a %bitset's index <em>counts from
   *  right to left</em>, to put it very loosely.
   *
   *  This behavior is preserved when translating to and from strings.  For
   *  example, the first line of the following program probably prints
   *  <em>b(&apos;a&apos;) is 0001100001</em> on a modern ASCII system.
   *
   *  @code
   *     #include <bitset>
   *     #include <iostream>
   *     #include <sstream>
   *
   *     using namespace std;
   *
   *     int main()
   *     {
   *         long         a = 'a';
   *         bitset<10>   b(a);
   *
   *         cout << "b('a') is " << b << endl;
   *
   *         ostringstream s;
   *         s << b;
   *         string  str = s.str();
   *         cout << "index 3 in the string is " << str[3] << " but\n"
   *              << "index 3 in the bitset is " << b[3] << endl;
   *     }
   *  @endcode
   *
   *  Also see:
   *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt12ch33s02.html
   *  for a de**ion of extensions.
   *
   *  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.
   *
   *  Extra confusion can result due to the fact that the storage for
   *  _Base_bitset @e is a regular array, and is indexed as such.  This is
   *  carefully encapsulated.
  */
  template<size_t _Nb>
    class bitset
    : private _Base_bitset<_GLIBCXX_BITSET_WORDS(_Nb)>
    {
    private:
      typedef _Base_bitset<_GLIBCXX_BITSET_WORDS(_Nb)> _Base;
      typedef unsigned long _WordT;

      template<class _CharT, class _Traits, class _Alloc>
      void
      _M_check_initial_position(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
                size_t __position) const
      {
    if (__position > __s.size())
      __throw_out_of_range_fmt(__N("bitset::bitset: __position "
                       "(which is %zu) > __s.size() "
                       "(which is %zu)"),
                   __position, __s.size());
      }

      void _M_check(size_t __position, const char *__s) const
      {
    if (__position >= _Nb)
      __throw_out_of_range_fmt(__N("%s: __position (which is %zu) "
                       ">= _Nb (which is %zu)"),
                   __s, __position, _Nb);
      }

      void
      _M_do_sanitize() _GLIBCXX_NOEXCEPT
      { 
    typedef _Sanitize<_Nb % _GLIBCXX_BITSET_BITS_PER_WORD> __sanitize_type;
    __sanitize_type::_S_do_sanitize(this->_M_hiword());
      }

#if __cplusplus >= 201103L
      template<typename> friend struct hash;
#endif

    public:
      /**
       *  This encapsulates the concept of a single bit.  An instance of this
       *  class is a proxy for an actual bit; this way the individual bit
       *  operations are done as faster word-size bitwise instructions.
       *
       *  Most users will never need to use this class directly; conversions
       *  to and from bool are automatic and should be transparent.  Overloaded
       *  operators help to preserve the illusion.
       *
       *  (On a typical system, this <em>bit %reference</em> is 64
       *  times the size of an actual bit.  Ha.)
       */
      class reference
      {
    friend class bitset;

    _WordT* _M_wp;
    size_t  _M_bpos;

    // left undefined
    reference();

      public:
    reference(bitset& __b, size_t __pos) _GLIBCXX_NOEXCEPT
    {
      _M_wp = &__b._M_getword(__pos);
      _M_bpos = _Base::_S_whichbit(__pos);
    }

    ~reference() _GLIBCXX_NOEXCEPT
    { }

    // For b[i] = __x;
    reference&
    operator=(bool __x) _GLIBCXX_NOEXCEPT
    {
      if (__x)
        *_M_wp |= _Base::_S_maskbit(_M_bpos);
      else
        *_M_wp &= ~_Base::_S_maskbit(_M_bpos);
      return *this;
    }

    // For b[i] = b[__j];
    reference&
    operator=(const reference& __j) _GLIBCXX_NOEXCEPT
    {
      if ((*(__j._M_wp) & _Base::_S_maskbit(__j._M_bpos)))
        *_M_wp |= _Base::_S_maskbit(_M_bpos);
      else
        *_M_wp &= ~_Base::_S_maskbit(_M_bpos);
      return *this;
    }

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

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

    // For b[i].flip();
    reference&
    flip() _GLIBCXX_NOEXCEPT
    {
      *_M_wp ^= _Base::_S_maskbit(_M_bpos);
      return *this;
    }
      };
      friend class reference;

      // 23.3.5.1 constructors:
      /// All bits set to zero.
      _GLIBCXX_CONSTEXPR bitset() _GLIBCXX_NOEXCEPT
      { }

      /// Initial bits bitwise-copied from a single word (others set to zero).
#if __cplusplus >= 201103L
      constexpr bitset(unsigned long long __val) noexcept
      : _Base(_Sanitize_val<_Nb>::_S_do_sanitize_val(__val)) { }
#else
      bitset(unsigned long __val)
      : _Base(__val)
      { _M_do_sanitize(); }
#endif

      /**
       *  Use a subset of a string.
       *  @param  __s  A string of @a 0 and @a 1 characters.
       *  @param  __position  Index of the first character in @a __s to use;
       *                    defaults to zero.
       *  @throw  std::out_of_range  If @a pos is bigger the size of @a __s.
       *  @throw  std::invalid_argument  If a character appears in the string
       *                                 which is neither @a 0 nor @a 1.
       */
      template<class _CharT, class _Traits, class _Alloc>
    explicit
    bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
           size_t __position = 0)
    : _Base()
    {
      _M_check_initial_position(__s, __position);
      _M_copy_from_string(__s, __position,
                  std::basic_string<_CharT, _Traits, _Alloc>::npos,
                  _CharT('0'), _CharT('1'));
    }

      /**
       *  Use a subset of a string.
       *  @param  __s  A string of @a 0 and @a 1 characters.
       *  @param  __position  Index of the first character in @a __s to use.
       *  @param  __n    The number of characters to copy.
       *  @throw std::out_of_range If @a __position is bigger the size
       *  of @a __s.
       *  @throw  std::invalid_argument  If a character appears in the string
       *                                 which is neither @a 0 nor @a 1.
       */
      template<class _CharT, class _Traits, class _Alloc>
    bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
           size_t __position, size_t __n)
    : _Base()
    {
      _M_check_initial_position(__s, __position);
      _M_copy_from_string(__s, __position, __n, _CharT('0'), _CharT('1'));
    }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      template<class _CharT, class _Traits, class _Alloc>
    bitset(const std::basic_string<_CharT, _Traits, _Alloc>& __s,
           size_t __position, size_t __n,
           _CharT __zero, _CharT __one = _CharT('1'))
    : _Base()
    {
      _M_check_initial_position(__s, __position);
      _M_copy_from_string(__s, __position, __n, __zero, __one);
    }

#if __cplusplus >= 201103L
      /**
       *  Construct from a character %array.
       *  @param  __str  An %array of characters @a zero and @a one.
       *  @param  __n    The number of characters to use.
       *  @param  __zero The character corresponding to the value 0.
       *  @param  __one  The character corresponding to the value 1.
       *  @throw  std::invalid_argument If a character appears in the string
       *                                which is neither @a __zero nor @a __one.
       */
      template<typename _CharT>
        explicit
        bitset(const _CharT* __str,
           typename std::basic_string<_CharT>::size_type __n
           = std::basic_string<_CharT>::npos,
           _CharT __zero = _CharT('0'), _CharT __one = _CharT('1'))
        : _Base()
        {
      if (!__str)
        __throw_logic_error(__N("bitset::bitset(const _CharT*, ...)"));

      if (__n == std::basic_string<_CharT>::npos)
        __n = std::char_traits<_CharT>::length(__str);
      _M_copy_from_ptr<_CharT, std::char_traits<_CharT>>(__str, __n, 0,
                                 __n, __zero,
                                 __one);
    }
#endif

      // 23.3.5.2 bitset operations:
      //@{
      /**
       *  Operations on bitsets.
       *  @param  __rhs  A same-sized bitset.
       *
       *  These should be self-explanatory.
       */
      bitset<_Nb>&
      operator&=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    this->_M_do_and(__rhs);
    return *this;
      }

      bitset<_Nb>&
      operator|=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    this->_M_do_or(__rhs);
    return *this;
      }

      bitset<_Nb>&
      operator^=(const bitset<_Nb>& __rhs) _GLIBCXX_NOEXCEPT
      {
    this->_M_do_xor(__rhs);
    return *this;
      }
      //@}

      //@{
      /**
       *  Operations on bitsets.
       *  @param  __position  The number of places to shift.
       *
       *  These should be self-explanatory.
       */
      bitset<_Nb>&
      operator<<=(size_t __position) _GLIBCXX_NOEXCEPT
      {
    if (__builtin_expect(__position < _Nb, 1))
      {
        this->_M_do_left_shift(__position);
        this->_M_do_sanitize();
      }
    else
      this->_M_do_reset();
    return *this;
      }

      bitset<_Nb>&
      operator>>=(size_t __position) _GLIBCXX_NOEXCEPT
      {
    if (__builtin_expect(__position < _Nb, 1))
      {
        this->_M_do_right_shift(__position);
        this->_M_do_sanitize();
      }
    else
      this->_M_do_reset();
    return *this;
      }
      //@}

      //@{
      /**
       *  These versions of single-bit set, reset, flip, and test are
       *  extensions from the SGI version.  They do no range checking.
       *  @ingroup SGIextensions
       */
      bitset<_Nb>&
      _Unchecked_set(size_t __pos) _GLIBCXX_NOEXCEPT
      {
    this->_M_getword(__pos) |= _Base::_S_maskbit(__pos);
    return *this;
      }

      bitset<_Nb>&
      _Unchecked_set(size_t __pos, int __val) _GLIBCXX_NOEXCEPT
      {
    if (__val)
      this->_M_getword(__pos) |= _Base::_S_maskbit(__pos);
    else
      this->_M_getword(__pos) &= ~_Base::_S_maskbit(__pos);
    return *this;
      }

      bitset<_Nb>&
      _Unchecked_reset(size_t __pos) _GLIBCXX_NOEXCEPT
      {
    this->_M_getword(__pos) &= ~_Base::_S_maskbit(__pos);
    return *this;
      }

      bitset<_Nb>&
      _Unchecked_flip(size_t __pos) _GLIBCXX_NOEXCEPT
      {
    this->_M_getword(__pos) ^= _Base::_S_maskbit(__pos);
    return *this;
      }

      _GLIBCXX_CONSTEXPR bool
      _Unchecked_test(size_t __pos) const _GLIBCXX_NOEXCEPT
      { return ((this->_M_getword(__pos) & _Base::_S_maskbit(__pos))
        != static_cast<_WordT>(0)); }
      //@}

      // Set, reset, and flip.
      /**
       *  @brief Sets every bit to true.
       */
      bitset<_Nb>&
      set() _GLIBCXX_NOEXCEPT
      {
    this->_M_do_set();
    this->_M_do_sanitize();
    return *this;
      }

      /**
       *  @brief Sets a given bit to a particular value.
       *  @param  __position  The index of the bit.
       *  @param  __val  Either true or false, defaults to true.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bitset<_Nb>&
      set(size_t __position, bool __val = true)
      {
    this->_M_check(__position, __N("bitset::set"));
    return _Unchecked_set(__position, __val);
      }

      /**
       *  @brief Sets every bit to false.
       */
      bitset<_Nb>&
      reset() _GLIBCXX_NOEXCEPT
      {
    this->_M_do_reset();
    return *this;
      }

      /**
       *  @brief Sets a given bit to false.
       *  @param  __position  The index of the bit.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       *
       *  Same as writing @c set(pos,false).
       */
      bitset<_Nb>&
      reset(size_t __position)
      {
    this->_M_check(__position, __N("bitset::reset"));
    return _Unchecked_reset(__position);
      }

      /**
       *  @brief Toggles every bit to its opposite value.
       */
      bitset<_Nb>&
      flip() _GLIBCXX_NOEXCEPT
      {
    this->_M_do_flip();
    this->_M_do_sanitize();
    return *this;
      }

      /**
       *  @brief Toggles a given bit to its opposite value.
       *  @param  __position  The index of the bit.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bitset<_Nb>&
      flip(size_t __position)
      {
    this->_M_check(__position, __N("bitset::flip"));
    return _Unchecked_flip(__position);
      }

      /// See the no-argument flip().
      bitset<_Nb>
      operator~() const _GLIBCXX_NOEXCEPT
      { return bitset<_Nb>(*this).flip(); }

      //@{
      /**
       *  @brief  Array-indexing support.
       *  @param  __position  Index into the %bitset.
       *  @return A bool for a <em>const %bitset</em>.  For non-const
       *           bitsets, an instance of the reference proxy class.
       *  @note  These operators do no range checking and throw no exceptions,
       *         as required by DR 11 to the standard.
       *
       *  _GLIBCXX_RESOLVE_LIB_DEFECTS Note that this implementation already
       *  resolves DR 11 (items 1 and 2), but does not do the range-checking
       *  required by that DR's resolution.  -pme
       *  The DR has since been changed:  range-checking is a precondition
       *  (users' responsibility), and these functions must not throw.  -pme
       */
      reference
      operator[](size_t __position)
      { return reference(*this, __position); }

      _GLIBCXX_CONSTEXPR bool
      operator[](size_t __position) const
      { return _Unchecked_test(__position); }
      //@}

      /**
       *  @brief Returns a numerical interpretation of the %bitset.
       *  @return  The integral equivalent of the bits.
       *  @throw  std::overflow_error  If there are too many bits to be
       *                               represented in an @c unsigned @c long.
       */
      unsigned long
      to_ulong() const
      { return this->_M_do_to_ulong(); }

#if __cplusplus >= 201103L
      unsigned long long
      to_ullong() const
      { return this->_M_do_to_ullong(); }
#endif

      /**
       *  @brief Returns a character interpretation of the %bitset.
       *  @return  The string equivalent of the bits.
       *
       *  Note the ordering of the bits:  decreasing character positions
       *  correspond to increasing bit positions (see the main class notes for
       *  an example).
       */
      template<class _CharT, class _Traits, class _Alloc>
    std::basic_string<_CharT, _Traits, _Alloc>
    to_string() const
    {
      std::basic_string<_CharT, _Traits, _Alloc> __result;
      _M_copy_to_string(__result, _CharT('0'), _CharT('1'));
      return __result;
    }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      template<class _CharT, class _Traits, class _Alloc>
    std::basic_string<_CharT, _Traits, _Alloc>
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    {
      std::basic_string<_CharT, _Traits, _Alloc> __result;
      _M_copy_to_string(__result, __zero, __one);
      return __result;
    }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 434. bitset::to_string() hard to use.
      template<class _CharT, class _Traits>
    std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
    to_string() const
    { return to_string<_CharT, _Traits, std::allocator<_CharT> >(); }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 853. to_string needs updating with zero and one.
      template<class _CharT, class _Traits>
    std::basic_string<_CharT, _Traits, std::allocator<_CharT> >
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    { return to_string<_CharT, _Traits,
                       std::allocator<_CharT> >(__zero, __one); }

      template<class _CharT>
    std::basic_string<_CharT, std::char_traits<_CharT>,
                      std::allocator<_CharT> >
    to_string() const
    {
      return to_string<_CharT, std::char_traits<_CharT>,
                       std::allocator<_CharT> >();
    }

      template<class _CharT>
    std::basic_string<_CharT, std::char_traits<_CharT>,
                      std::allocator<_CharT> >
    to_string(_CharT __zero, _CharT __one = _CharT('1')) const
    {
      return to_string<_CharT, std::char_traits<_CharT>,
                       std::allocator<_CharT> >(__zero, __one);
    }

      std::basic_string<char, std::char_traits<char>, std::allocator<char> >
      to_string() const
      {
    return to_string<char, std::char_traits<char>,
                     std::allocator<char> >();
      }

      std::basic_string<char, std::char_traits<char>, std::allocator<char> >
      to_string(char __zero, char __one = '1') const
      {
    return to_string<char, std::char_traits<char>,
                     std::allocator<char> >(__zero, __one);
      }

      // Helper functions for string operations.
      template<class _CharT, class _Traits>
        void
        _M_copy_from_ptr(const _CharT*, size_t, size_t, size_t,
             _CharT, _CharT);

      template<class _CharT, class _Traits, class _Alloc>
    void
    _M_copy_from_string(const std::basic_string<_CharT,
                _Traits, _Alloc>& __s, size_t __pos, size_t __n,
                _CharT __zero, _CharT __one)
    { _M_copy_from_ptr<_CharT, _Traits>(__s.data(), __s.size(), __pos, __n,
                        __zero, __one); }

      template<class _CharT, class _Traits, class _Alloc>
    void
        _M_copy_to_string(std::basic_string<_CharT, _Traits, _Alloc>&,
              _CharT, _CharT) const;

      // NB: Backward compat.
      template<class _CharT, class _Traits, class _Alloc>
    void
    _M_copy_from_string(const std::basic_string<_CharT,
                _Traits, _Alloc>& __s, size_t __pos, size_t __n)
    { _M_copy_from_string(__s, __pos, __n, _CharT('0'), _CharT('1')); }

      template<class _CharT, class _Traits, class _Alloc>
    void
        _M_copy_to_string(std::basic_string<_CharT, _Traits,_Alloc>& __s) const
    { _M_copy_to_string(__s, _CharT('0'), _CharT('1')); }

      /// Returns the number of bits which are set.
      size_t
      count() const _GLIBCXX_NOEXCEPT
      { return this->_M_do_count(); }

      /// Returns the total number of bits.
      _GLIBCXX_CONSTEXPR size_t
      size() const _GLIBCXX_NOEXCEPT
      { return _Nb; }

      //@{
      /// These comparisons for equality/inequality are, well, @e bitwise.
      bool
      operator==(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
      { return this->_M_is_equal(__rhs); }

      bool
      operator!=(const bitset<_Nb>& __rhs) const _GLIBCXX_NOEXCEPT
      { return !this->_M_is_equal(__rhs); }
      //@}

      /**
       *  @brief Tests the value of a bit.
       *  @param  __position  The index of a bit.
       *  @return  The value at @a pos.
       *  @throw  std::out_of_range  If @a pos is bigger the size of the %set.
       */
      bool
      test(size_t __position) const
      {
    this->_M_check(__position, __N("bitset::test"));
    return _Unchecked_test(__position);
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // DR 693. std::bitset::all() missing.
      /**
       *  @brief Tests whether all the bits are on.
       *  @return  True if all the bits are set.
       */
      bool
      all() const _GLIBCXX_NOEXCEPT
      { return this->template _M_are_all<_Nb>(); }

      /**
       *  @brief Tests whether any of the bits are on.
       *  @return  True if at least one bit is set.
       */
      bool
      any() const _GLIBCXX_NOEXCEPT
      { return this->_M_is_any(); }

      /**
       *  @brief Tests whether any of the bits are on.
       *  @return  True if none of the bits are set.
       */
      bool
      none() const _GLIBCXX_NOEXCEPT
      { return !this->_M_is_any(); }

      //@{
      /// Self-explanatory.
      bitset<_Nb>
      operator<<(size_t __position) const _GLIBCXX_NOEXCEPT
      { return bitset<_Nb>(*this) <<= __position; }

      bitset<_Nb>
      operator>>(size_t __position) const _GLIBCXX_NOEXCEPT
      { return bitset<_Nb>(*this) >>= __position; }
      //@}

      /**
       *  @brief  Finds the index of the first "on" bit.
       *  @return  The index of the first bit set, or size() if not found.
       *  @ingroup SGIextensions
       *  @sa  _Find_next
       */
      size_t
      _Find_first() const _GLIBCXX_NOEXCEPT
      { return this->_M_do_find_first(_Nb); }

      /**
       *  @brief  Finds the index of the next "on" bit after prev.
       *  @return  The index of the next bit set, or size() if not found.
       *  @param  __prev  Where to start searching.
       *  @ingroup SGIextensions
       *  @sa  _Find_first
       */
      size_t
      _Find_next(size_t __prev) const _GLIBCXX_NOEXCEPT
      { return this->_M_do_find_next(__prev, _Nb); }
    };

  // Definitions of non-inline member functions.
  template<size_t _Nb>
    template<class _CharT, class _Traits>
      void
      bitset<_Nb>::
      _M_copy_from_ptr(const _CharT* __s, size_t __len,
               size_t __pos, size_t __n, _CharT __zero, _CharT __one)
      {
    reset();
    const size_t __nbits = std::min(_Nb, std::min(__n, size_t(__len - __pos)));
    for (size_t __i = __nbits; __i > 0; --__i)
      {
        const _CharT __c = __s[__pos + __nbits - __i];
        if (_Traits::eq(__c, __zero))
          ;
        else if (_Traits::eq(__c, __one))
          _Unchecked_set(__i - 1);
        else
          __throw_invalid_argument(__N("bitset::_M_copy_from_ptr"));
      }
      }

  template<size_t _Nb>
    template<class _CharT, class _Traits, class _Alloc>
      void
      bitset<_Nb>::
      _M_copy_to_string(std::basic_string<_CharT, _Traits, _Alloc>& __s,
            _CharT __zero, _CharT __one) const
      {
    __s.assign(_Nb, __zero);
    for (size_t __i = _Nb; __i > 0; --__i)
      if (_Unchecked_test(__i - 1))
        _Traits::assign(__s[_Nb - __i], __one);
      }

  // 23.3.5.3 bitset operations:
  //@{
  /**
   *  @brief  Global bitwise operations on bitsets.
   *  @param  __x  A bitset.
   *  @param  __y  A bitset of the same size as @a __x.
   *  @return  A new bitset.
   *
   *  These should be self-explanatory.
  */
  template<size_t _Nb>
    inline bitset<_Nb>
    operator&(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    {
      bitset<_Nb> __result(__x);
      __result &= __y;
      return __result;
    }

  template<size_t _Nb>
    inline bitset<_Nb>
    operator|(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    {
      bitset<_Nb> __result(__x);
      __result |= __y;
      return __result;
    }

  template <size_t _Nb>
    inline bitset<_Nb>
    operator^(const bitset<_Nb>& __x, const bitset<_Nb>& __y) _GLIBCXX_NOEXCEPT
    {
      bitset<_Nb> __result(__x);
      __result ^= __y;
      return __result;
    }
  //@}

  //@{
  /**
   *  @brief Global I/O operators for bitsets.
   *
   *  Direct I/O between streams and bitsets is supported.  Output is
   *  straightforward.  Input will skip whitespace, only accept @a 0 and @a 1
   *  characters, and will only extract as many digits as the %bitset will
   *  hold.
  */
  template<class _CharT, class _Traits, size_t _Nb>
    std::basic_istream<_CharT, _Traits>&
    operator>>(std::basic_istream<_CharT, _Traits>& __is, bitset<_Nb>& __x)
    {
      typedef typename _Traits::char_type          char_type;
      typedef std::basic_istream<_CharT, _Traits>  __istream_type;
      typedef typename __istream_type::ios_base    __ios_base;

      std::basic_string<_CharT, _Traits> __tmp;
      __tmp.reserve(_Nb);

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 303. Bitset input operator underspecified
      const char_type __zero = __is.widen('0');
      const char_type __one = __is.widen('1');

      typename __ios_base::iostate __state = __ios_base::goodbit;
      typename __istream_type::sentry __sentry(__is);
      if (__sentry)
    {
      __try
        {
          for (size_t __i = _Nb; __i > 0; --__i)
        {
          static typename _Traits::int_type __eof = _Traits::eof();

          typename _Traits::int_type __c1 = __is.rdbuf()->sbumpc();
          if (_Traits::eq_int_type(__c1, __eof))
            {
              __state |= __ios_base::eofbit;
              break;
            }
          else
            {
              const char_type __c2 = _Traits::to_char_type(__c1);
              if (_Traits::eq(__c2, __zero))
            __tmp.push_back(__zero);
              else if (_Traits::eq(__c2, __one))
            __tmp.push_back(__one);
              else if (_Traits::
                   eq_int_type(__is.rdbuf()->sputbackc(__c2),
                       __eof))
            {
              __state |= __ios_base::failbit;
              break;
            }
            }
        }
        }
      __catch(__cxxabiv1::__forced_unwind&)
        {
          __is._M_setstate(__ios_base::badbit);     
          __throw_exception_again;
        }
      __catch(...)
        { __is._M_setstate(__ios_base::badbit); }
    }

      if (__tmp.empty() && _Nb)
    __state |= __ios_base::failbit;
      else
    __x._M_copy_from_string(__tmp, static_cast<size_t>(0), _Nb,
                __zero, __one);
      if (__state)
    __is.setstate(__state);
      return __is;
    }

  template <class _CharT, class _Traits, size_t _Nb>
    std::basic_ostream<_CharT, _Traits>&
    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
           const bitset<_Nb>& __x)
    {
      std::basic_string<_CharT, _Traits> __tmp;

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 396. what are characters zero and one.
      const ctype<_CharT>& __ct = use_facet<ctype<_CharT> >(__os.getloc());
      __x._M_copy_to_string(__tmp, __ct.widen('0'), __ct.widen('1'));
      return __os << __tmp;
    }
  //@}

_GLIBCXX_END_NAMESPACE_CONTAINER
} // namespace std

#undef _GLIBCXX_BITSET_WORDS
#undef _GLIBCXX_BITSET_BITS_PER_WORD
#undef _GLIBCXX_BITSET_BITS_PER_ULL

#if __cplusplus >= 201103L

#include <bits/functional_hash.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // DR 1182.
  /// std::hash specialization for bitset.
  template<size_t _Nb>
    struct hash<_GLIBCXX_STD_C::bitset<_Nb>>
    : public __hash_base<size_t, _GLIBCXX_STD_C::bitset<_Nb>>
    {
      size_t
      operator()(const _GLIBCXX_STD_C::bitset<_Nb>& __b) const noexcept
      {
    const size_t __clength = (_Nb + __CHAR_BIT__ - 1) / __CHAR_BIT__;
    return std::_Hash_impl::hash(__b._M_getdata(), __clength);
      }
    };

  template<>
    struct hash<_GLIBCXX_STD_C::bitset<0>>
    : public __hash_base<size_t, _GLIBCXX_STD_C::bitset<0>>
    {
      size_t
      operator()(const _GLIBCXX_STD_C::bitset<0>&) const noexcept
      { return 0; }
    };

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif // C++11

#ifdef _GLIBCXX_DEBUG
# include <debug/bitset>
#endif

#ifdef _GLIBCXX_PROFILE
# include <profile/bitset>
#endif

#endif /* _GLIBCXX_BITSET */

 


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