Subversion Repositories altor32

// Temporary buffer implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,

// 2010, 2011, 2012

// 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) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996,1997

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/** @file bits/stl_tempbuf.h

 *  This is an internal header file, included by other library headers.

 *  Do not attempt to use it directly. @headername{memory}

 */

#ifndef _STL_TEMPBUF_H

#define _STL_TEMPBUF_H 1

#include <bits/stl_algobase.h>

#include <bits/stl_construct.h>

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**

   *  @brief Allocates a temporary buffer.

   *  @param  __len  The number of objects of type Tp.

   *  @return See full description.

   *

   *  Reinventing the wheel, but this time with prettier spokes!

   *

   *  This function tries to obtain storage for @c __len adjacent Tp

   *  objects.  The objects themselves are not constructed, of course.

   *  A pair<> is returned containing <em>the buffer s address and

   *  capacity (in the units of sizeof(_Tp)), or a pair of 0 values if

   *  no storage can be obtained.</em>  Note that the capacity obtained

   *  may be less than that requested if the memory is unavailable;

   *  you should compare len with the .second return value.

   *

   * Provides the nothrow exception guarantee.

   */

  template<typename _Tp>

    pair<_Tp*, ptrdiff_t>

    get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT

    {

      const ptrdiff_t __max =

        __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp);

      if (__len > __max)

        __len = __max;

      while (__len > 0)

        {

          _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp),

                                                        std::nothrow));

          if (__tmp != 0)

            return std::pair<_Tp*, ptrdiff_t>(__tmp, __len);

          __len /= 2;

        }

      return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0);

    }

  /**

   *  @brief The companion to get_temporary_buffer().

   *  @param  __p  A buffer previously allocated by get_temporary_buffer.

   *  @return   None.

   *

   *  Frees the memory pointed to by __p.

   */

  template<typename _Tp>

    inline void

    return_temporary_buffer(_Tp* __p)

    { ::operator delete(__p, std::nothrow); }

  /**

   *  This class is used in two places: stl_algo.h and ext/memory,

   *  where it is wrapped as the temporary_buffer class.  See

   *  temporary_buffer docs for more notes.

   */

  template<typename _ForwardIterator, typename _Tp>

    class _Temporary_buffer

    {

      // concept requirements

      __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept)

    public:

      typedef _Tp         value_type;

      typedef value_type* pointer;

      typedef pointer     iterator;

      typedef ptrdiff_t   size_type;

    protected:

      size_type  _M_original_len;

      size_type  _M_len;

      pointer    _M_buffer;

    public:

      /// As per Table mumble.

      size_type

      size() const

      { return _M_len; }

      /// Returns the size requested by the constructor; may be >size().

      size_type

      requested_size() const

      { return _M_original_len; }

      /// As per Table mumble.

      iterator

      begin()

      { return _M_buffer; }

      /// As per Table mumble.

      iterator

      end()

      { return _M_buffer + _M_len; }

      /**

       * Constructs a temporary buffer of a size somewhere between

       * zero and the size of the given range.

       */

      _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last);

      ~_Temporary_buffer()

      {

        std::_Destroy(_M_buffer, _M_buffer + _M_len);

        std::return_temporary_buffer(_M_buffer);

      }

    private:

      // Disable copy constructor and assignment operator.

      _Temporary_buffer(const _Temporary_buffer&);

      void

      operator=(const _Temporary_buffer&);

    };

  template<bool>

    struct __uninitialized_construct_buf_dispatch

    {

      template<typename _Pointer, typename _ForwardIterator>

        static void

        __ucr(_Pointer __first, _Pointer __last,

              _ForwardIterator __seed)

        {

          if(__first == __last)

            return;

          _Pointer __cur = __first;

          __try

            {

              std::_Construct(std::__addressof(*__first),

                              _GLIBCXX_MOVE(*__seed));

              _Pointer __prev = __cur;

              ++__cur;

              for(; __cur != __last; ++__cur, ++__prev)

                std::_Construct(std::__addressof(*__cur),

                                _GLIBCXX_MOVE(*__prev));

              *__seed = _GLIBCXX_MOVE(*__prev);

            }

          __catch(...)

            {

              std::_Destroy(__first, __cur);

              __throw_exception_again;

            }

        }

    };

  template<>

    struct __uninitialized_construct_buf_dispatch<true>

    {

      template<typename _Pointer, typename _ForwardIterator>

        static void

        __ucr(_Pointer, _Pointer, _ForwardIterator) { }

    };

  // Constructs objects in the range [first, last).

  // Note that while these new objects will take valid values,

  // their exact value is not defined. In particular they may

  // be 'moved from'.

  //

  // While *__seed may be altered during this algorithm, it will have

  // the same value when the algorithm finishes, unless one of the

  // constructions throws.

  //

  // Requirements: _Pointer::value_type(_Tp&&) is valid.

  template<typename _Pointer, typename _ForwardIterator>

    inline void

    __uninitialized_construct_buf(_Pointer __first, _Pointer __last,

                                  _ForwardIterator __seed)

    {

      typedef typename std::iterator_traits<_Pointer>::value_type

        _ValueType;

      std::__uninitialized_construct_buf_dispatch<

        __has_trivial_constructor(_ValueType)>::

          __ucr(__first, __last, __seed);

    }

  template<typename _ForwardIterator, typename _Tp>

    _Temporary_buffer<_ForwardIterator, _Tp>::

    _Temporary_buffer(_ForwardIterator __first, _ForwardIterator __last)

    : _M_original_len(std::distance(__first, __last)),

      _M_len(0), _M_buffer(0)

    {

      __try

        {

          std::pair<pointer, size_type> __p(std::get_temporary_buffer<

                                            value_type>(_M_original_len));

          _M_buffer = __p.first;

          _M_len = __p.second;

          if (_M_buffer)

            std::__uninitialized_construct_buf(_M_buffer, _M_buffer + _M_len,

                                               __first);

        }

      __catch(...)

        {

          std::return_temporary_buffer(_M_buffer);

          _M_buffer = 0;

          _M_len = 0;

          __throw_exception_again;

        }

    }

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace

#endif /* _STL_TEMPBUF_H */