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// Types used in iterator implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

// 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) 1996-1998

 * Silicon Graphics Computer Systems, Inc.

 *

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

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

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

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

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

 */

/** @file bits/stl_iterator_base_types.h

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

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

 *

 *  This file contains all of the general iterator-related utility types,

 *  such as iterator_traits and struct iterator.

 */

#ifndef _STL_ITERATOR_BASE_TYPES_H

#define _STL_ITERATOR_BASE_TYPES_H 1

#pragma GCC system_header

#include <bits/c++config.h>

#ifdef __GXX_EXPERIMENTAL_CXX0X__

# include <type_traits>  // For _GLIBCXX_HAS_NESTED_TYPE

#endif

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**

   *  @defgroup iterators Iterators

   *  Abstractions for uniform iterating through various underlying types.

  */

  //@{ 

  /**

   *  @defgroup iterator_tags Iterator Tags

   *  These are empty types, used to distinguish different iterators.  The

   *  distinction is not made by what they contain, but simply by what they

   *  are.  Different underlying algorithms can then be used based on the

   *  different operations supported by different iterator types.

  */

  //@{ 

  ///  Marking input iterators.

  struct input_iterator_tag { };

  ///  Marking output iterators.

  struct output_iterator_tag { };

  /// Forward iterators support a superset of input iterator operations.

  struct forward_iterator_tag : public input_iterator_tag { };

  /// Bidirectional iterators support a superset of forward iterator

  /// operations.

  struct bidirectional_iterator_tag : public forward_iterator_tag { };

  /// Random-access iterators support a superset of bidirectional

  /// iterator operations.

  struct random_access_iterator_tag : public bidirectional_iterator_tag { };

  //@}

  /**

   *  @brief  Common %iterator class.

   *

   *  This class does nothing but define nested typedefs.  %Iterator classes

   *  can inherit from this class to save some work.  The typedefs are then

   *  used in specializations and overloading.

   *

   *  In particular, there are no default implementations of requirements

   *  such as @c operator++ and the like.  (How could there be?)

  */

  template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,

           typename _Pointer = _Tp*, typename _Reference = _Tp&>

    struct iterator

    {

      /// One of the @link iterator_tags tag types@endlink.

      typedef _Category  iterator_category;

      /// The type "pointed to" by the iterator.

      typedef _Tp        value_type;

      /// Distance between iterators is represented as this type.

      typedef _Distance  difference_type;

      /// This type represents a pointer-to-value_type.

      typedef _Pointer   pointer;

      /// This type represents a reference-to-value_type.

      typedef _Reference reference;

    };

  /**

   *  @brief  Traits class for iterators.

   *

   *  This class does nothing but define nested typedefs.  The general

   *  version simply @a forwards the nested typedefs from the Iterator

   *  argument.  Specialized versions for pointers and pointers-to-const

   *  provide tighter, more correct semantics.

  */

#ifdef __GXX_EXPERIMENTAL_CXX0X__

_GLIBCXX_HAS_NESTED_TYPE(iterator_category)

  template<typename _Iterator,

           bool = __has_iterator_category<_Iterator>::value>

    struct __iterator_traits { };

  template<typename _Iterator>

    struct __iterator_traits<_Iterator, true>

    {

      typedef typename _Iterator::iterator_category iterator_category;

      typedef typename _Iterator::value_type        value_type;

      typedef typename _Iterator::difference_type   difference_type;

      typedef typename _Iterator::pointer           pointer;

      typedef typename _Iterator::reference         reference;

    };

  template<typename _Iterator>

    struct iterator_traits

    : public __iterator_traits<_Iterator> { };

#else

  template<typename _Iterator>

    struct iterator_traits

    {

      typedef typename _Iterator::iterator_category iterator_category;

      typedef typename _Iterator::value_type        value_type;

      typedef typename _Iterator::difference_type   difference_type;

      typedef typename _Iterator::pointer           pointer;

      typedef typename _Iterator::reference         reference;

    };

#endif

  /// Partial specialization for pointer types.

  template<typename _Tp>

    struct iterator_traits<_Tp*>

    {

      typedef random_access_iterator_tag iterator_category;

      typedef _Tp                         value_type;

      typedef ptrdiff_t                   difference_type;

      typedef _Tp*                        pointer;

      typedef _Tp&                        reference;

    };

  /// Partial specialization for const pointer types.

  template<typename _Tp>

    struct iterator_traits<const _Tp*>

    {

      typedef random_access_iterator_tag iterator_category;

      typedef _Tp                         value_type;

      typedef ptrdiff_t                   difference_type;

      typedef const _Tp*                  pointer;

      typedef const _Tp&                  reference;

    };

  /**

   *  This function is not a part of the C++ standard but is syntactic

   *  sugar for internal library use only.

  */

  template<typename _Iter>

    inline typename iterator_traits<_Iter>::iterator_category

    __iterator_category(const _Iter&)

    { return typename iterator_traits<_Iter>::iterator_category(); }

  //@}

  // If _Iterator has a base returns it otherwise _Iterator is returned

  // untouched

  template<typename _Iterator, bool _HasBase>

    struct _Iter_base

    {

      typedef _Iterator iterator_type;

      static iterator_type _S_base(_Iterator __it)

      { return __it; }

    };

  template<typename _Iterator>

    struct _Iter_base<_Iterator, true>

    {

      typedef typename _Iterator::iterator_type iterator_type;

      static iterator_type _S_base(_Iterator __it)

      { return __it.base(); }

    };

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace

#endif /* _STL_ITERATOR_BASE_TYPES_H */