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// Iterators -*- 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) 1996-1998

 * 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.h

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

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

 *

 *  This file implements reverse_iterator, back_insert_iterator,

 *  front_insert_iterator, insert_iterator, __normal_iterator, and their

 *  supporting functions and overloaded operators.

 */

#ifndef _STL_ITERATOR_H

#define _STL_ITERATOR_H 1

#include <bits/cpp_type_traits.h>

#include <ext/type_traits.h>

#include <bits/move.h>

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  /**

   * @addtogroup iterators

   * @{

   */

  // 24.4.1 Reverse iterators

  /**

   *  Bidirectional and random access iterators have corresponding reverse

   *  %iterator adaptors that iterate through the data structure in the

   *  opposite direction.  They have the same signatures as the corresponding

   *  iterators.  The fundamental relation between a reverse %iterator and its

   *  corresponding %iterator @c i is established by the identity:

   *  @code

   *      &*(reverse_iterator(i)) == &*(i - 1)

   *  @endcode

   *

   *  <em>This mapping is dictated by the fact that while there is always a

   *  pointer past the end of an array, there might not be a valid pointer

   *  before the beginning of an array.</em> [24.4.1]/1,2

   *

   *  Reverse iterators can be tricky and surprising at first.  Their

   *  semantics make sense, however, and the trickiness is a side effect of

   *  the requirement that the iterators must be safe.

  */

  template<typename _Iterator>

    class reverse_iterator

    : public iterator<typename iterator_traits<_Iterator>::iterator_category,

                      typename iterator_traits<_Iterator>::value_type,

                      typename iterator_traits<_Iterator>::difference_type,

                      typename iterator_traits<_Iterator>::pointer,

                      typename iterator_traits<_Iterator>::reference>

    {

    protected:

      _Iterator current;

      typedef iterator_traits<_Iterator>                __traits_type;

    public:

      typedef _Iterator                                 iterator_type;

      typedef typename __traits_type::difference_type   difference_type;

      typedef typename __traits_type::pointer           pointer;

      typedef typename __traits_type::reference         reference;

      /**

       *  The default constructor value-initializes member @p current.

       *  If it is a pointer, that means it is zero-initialized.

      */

      // _GLIBCXX_RESOLVE_LIB_DEFECTS

      // 235 No specification of default ctor for reverse_iterator

      reverse_iterator() : current() { }

      /**

       *  This %iterator will move in the opposite direction that @p x does.

      */

      explicit

      reverse_iterator(iterator_type __x) : current(__x) { }

      /**

       *  The copy constructor is normal.

      */

      reverse_iterator(const reverse_iterator& __x)

      : current(__x.current) { }

      /**

       *  A %reverse_iterator across other types can be copied if the

       *  underlying %iterator can be converted to the type of @c current.

      */

      template<typename _Iter>

        reverse_iterator(const reverse_iterator<_Iter>& __x)

        : current(__x.base()) { }

      /**

       *  @return  @c current, the %iterator used for underlying work.

      */

      iterator_type

      base() const

      { return current; }

      /**

       *  @return  A reference to the value at @c --current

       *

       *  This requires that @c --current is dereferenceable.

       *

       *  @warning This implementation requires that for an iterator of the

       *           underlying iterator type, @c x, a reference obtained by

       *           @c *x remains valid after @c x has been modified or

       *           destroyed. This is a bug: http://gcc.gnu.org/PR51823

      */

      reference

      operator*() const

      {

        _Iterator __tmp = current;

        return *--__tmp;

      }

      /**

       *  @return  A pointer to the value at @c --current

       *

       *  This requires that @c --current is dereferenceable.

      */

      pointer

      operator->() const

      { return &(operator*()); }

      /**

       *  @return  @c *this

       *

       *  Decrements the underlying iterator.

      */

      reverse_iterator&

      operator++()

      {

        --current;

        return *this;

      }

      /**

       *  @return  The original value of @c *this

       *

       *  Decrements the underlying iterator.

      */

      reverse_iterator

      operator++(int)

      {

        reverse_iterator __tmp = *this;

        --current;

        return __tmp;

      }

      /**

       *  @return  @c *this

       *

       *  Increments the underlying iterator.

      */

      reverse_iterator&

      operator--()

      {

        ++current;

        return *this;

      }

      /**

       *  @return  A reverse_iterator with the previous value of @c *this

       *

       *  Increments the underlying iterator.

      */

      reverse_iterator

      operator--(int)

      {

        reverse_iterator __tmp = *this;

        ++current;

        return __tmp;

      }

      /**

       *  @return  A reverse_iterator that refers to @c current - @a __n

       *

       *  The underlying iterator must be a Random Access Iterator.

      */

      reverse_iterator

      operator+(difference_type __n) const

      { return reverse_iterator(current - __n); }

      /**

       *  @return  *this

       *

       *  Moves the underlying iterator backwards @a __n steps.

       *  The underlying iterator must be a Random Access Iterator.

      */

      reverse_iterator&

      operator+=(difference_type __n)

      {

        current -= __n;

        return *this;

      }

      /**

       *  @return  A reverse_iterator that refers to @c current - @a __n

       *

       *  The underlying iterator must be a Random Access Iterator.

      */

      reverse_iterator

      operator-(difference_type __n) const

      { return reverse_iterator(current + __n); }

      /**

       *  @return  *this

       *

       *  Moves the underlying iterator forwards @a __n steps.

       *  The underlying iterator must be a Random Access Iterator.

      */

      reverse_iterator&

      operator-=(difference_type __n)

      {

        current += __n;

        return *this;

      }

      /**

       *  @return  The value at @c current - @a __n - 1

       *

       *  The underlying iterator must be a Random Access Iterator.

      */

      reference

      operator[](difference_type __n) const

      { return *(*this + __n); }

    };

  //@{

  /**

   *  @param  __x  A %reverse_iterator.

   *  @param  __y  A %reverse_iterator.

   *  @return  A simple bool.

   *

   *  Reverse iterators forward many operations to their underlying base()

   *  iterators.  Others are implemented in terms of one another.

   *

  */

  template<typename _Iterator>

    inline bool

    operator==(const reverse_iterator<_Iterator>& __x,

               const reverse_iterator<_Iterator>& __y)

    { return __x.base() == __y.base(); }

  template<typename _Iterator>

    inline bool

    operator<(const reverse_iterator<_Iterator>& __x,

              const reverse_iterator<_Iterator>& __y)

    { return __y.base() < __x.base(); }

  template<typename _Iterator>

    inline bool

    operator!=(const reverse_iterator<_Iterator>& __x,

               const reverse_iterator<_Iterator>& __y)

    { return !(__x == __y); }

  template<typename _Iterator>

    inline bool

    operator>(const reverse_iterator<_Iterator>& __x,

              const reverse_iterator<_Iterator>& __y)

    { return __y < __x; }

  template<typename _Iterator>

    inline bool

    operator<=(const reverse_iterator<_Iterator>& __x,

               const reverse_iterator<_Iterator>& __y)

    { return !(__y < __x); }

  template<typename _Iterator>

    inline bool

    operator>=(const reverse_iterator<_Iterator>& __x,

               const reverse_iterator<_Iterator>& __y)

    { return !(__x < __y); }

  template<typename _Iterator>

    inline typename reverse_iterator<_Iterator>::difference_type

    operator-(const reverse_iterator<_Iterator>& __x,

              const reverse_iterator<_Iterator>& __y)

    { return __y.base() - __x.base(); }

  template<typename _Iterator>

    inline reverse_iterator<_Iterator>

    operator+(typename reverse_iterator<_Iterator>::difference_type __n,

              const reverse_iterator<_Iterator>& __x)

    { return reverse_iterator<_Iterator>(__x.base() - __n); }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS

  // DR 280. Comparison of reverse_iterator to const reverse_iterator.

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator==(const reverse_iterator<_IteratorL>& __x,

               const reverse_iterator<_IteratorR>& __y)

    { return __x.base() == __y.base(); }

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator<(const reverse_iterator<_IteratorL>& __x,

              const reverse_iterator<_IteratorR>& __y)

    { return __y.base() < __x.base(); }

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator!=(const reverse_iterator<_IteratorL>& __x,

               const reverse_iterator<_IteratorR>& __y)

    { return !(__x == __y); }

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator>(const reverse_iterator<_IteratorL>& __x,

              const reverse_iterator<_IteratorR>& __y)

    { return __y < __x; }

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator<=(const reverse_iterator<_IteratorL>& __x,

               const reverse_iterator<_IteratorR>& __y)

    { return !(__y < __x); }

  template<typename _IteratorL, typename _IteratorR>

    inline bool

    operator>=(const reverse_iterator<_IteratorL>& __x,

               const reverse_iterator<_IteratorR>& __y)

    { return !(__x < __y); }

  template<typename _IteratorL, typename _IteratorR>

#if __cplusplus >= 201103L

    // DR 685.

    inline auto

    operator-(const reverse_iterator<_IteratorL>& __x,

              const reverse_iterator<_IteratorR>& __y)

    -> decltype(__y.base() - __x.base())

#else

    inline typename reverse_iterator<_IteratorL>::difference_type

    operator-(const reverse_iterator<_IteratorL>& __x,

              const reverse_iterator<_IteratorR>& __y)

#endif

    { return __y.base() - __x.base(); }

  //@}

  // 24.4.2.2.1 back_insert_iterator

  /**

   *  @brief  Turns assignment into insertion.

   *

   *  These are output iterators, constructed from a container-of-T.

   *  Assigning a T to the iterator appends it to the container using

   *  push_back.

   *

   *  Tip:  Using the back_inserter function to create these iterators can

   *  save typing.

  */

  template<typename _Container>

    class back_insert_iterator

    : public iterator<output_iterator_tag, void, void, void, void>

    {

    protected:

      _Container* container;

    public:

      /// A nested typedef for the type of whatever container you used.

      typedef _Container          container_type;

      /// The only way to create this %iterator is with a container.

      explicit

      back_insert_iterator(_Container& __x) : container(&__x) { }

      /**

       *  @param  __value  An instance of whatever type

       *                 container_type::const_reference is; presumably a

       *                 reference-to-const T for container<T>.

       *  @return  This %iterator, for chained operations.

       *

       *  This kind of %iterator doesn't really have a @a position in the

       *  container (you can think of the position as being permanently at

       *  the end, if you like).  Assigning a value to the %iterator will

       *  always append the value to the end of the container.

      */

#if __cplusplus < 201103L

      back_insert_iterator&

      operator=(typename _Container::const_reference __value)

      {

        container->push_back(__value);

        return *this;

      }

#else

      back_insert_iterator&

      operator=(const typename _Container::value_type& __value)

      {

        container->push_back(__value);

        return *this;

      }

      back_insert_iterator&

      operator=(typename _Container::value_type&& __value)

      {

        container->push_back(std::move(__value));

        return *this;

      }

#endif

      /// Simply returns *this.

      back_insert_iterator&

      operator*()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      back_insert_iterator&

      operator++()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      back_insert_iterator

      operator++(int)

      { return *this; }

    };

  /**

   *  @param  __x  A container of arbitrary type.

   *  @return  An instance of back_insert_iterator working on @p __x.

   *

   *  This wrapper function helps in creating back_insert_iterator instances.

   *  Typing the name of the %iterator requires knowing the precise full

   *  type of the container, which can be tedious and impedes generic

   *  programming.  Using this function lets you take advantage of automatic

   *  template parameter deduction, making the compiler match the correct

   *  types for you.

  */

  template<typename _Container>

    inline back_insert_iterator<_Container>

    back_inserter(_Container& __x)

    { return back_insert_iterator<_Container>(__x); }

  /**

   *  @brief  Turns assignment into insertion.

   *

   *  These are output iterators, constructed from a container-of-T.

   *  Assigning a T to the iterator prepends it to the container using

   *  push_front.

   *

   *  Tip:  Using the front_inserter function to create these iterators can

   *  save typing.

  */

  template<typename _Container>

    class front_insert_iterator

    : public iterator<output_iterator_tag, void, void, void, void>

    {

    protected:

      _Container* container;

    public:

      /// A nested typedef for the type of whatever container you used.

      typedef _Container          container_type;

      /// The only way to create this %iterator is with a container.

      explicit front_insert_iterator(_Container& __x) : container(&__x) { }

      /**

       *  @param  __value  An instance of whatever type

       *                 container_type::const_reference is; presumably a

       *                 reference-to-const T for container<T>.

       *  @return  This %iterator, for chained operations.

       *

       *  This kind of %iterator doesn't really have a @a position in the

       *  container (you can think of the position as being permanently at

       *  the front, if you like).  Assigning a value to the %iterator will

       *  always prepend the value to the front of the container.

      */

#if __cplusplus < 201103L

      front_insert_iterator&

      operator=(typename _Container::const_reference __value)

      {

        container->push_front(__value);

        return *this;

      }

#else

      front_insert_iterator&

      operator=(const typename _Container::value_type& __value)

      {

        container->push_front(__value);

        return *this;

      }

      front_insert_iterator&

      operator=(typename _Container::value_type&& __value)

      {

        container->push_front(std::move(__value));

        return *this;

      }

#endif

      /// Simply returns *this.

      front_insert_iterator&

      operator*()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      front_insert_iterator&

      operator++()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      front_insert_iterator

      operator++(int)

      { return *this; }

    };

  /**

   *  @param  __x  A container of arbitrary type.

   *  @return  An instance of front_insert_iterator working on @p x.

   *

   *  This wrapper function helps in creating front_insert_iterator instances.

   *  Typing the name of the %iterator requires knowing the precise full

   *  type of the container, which can be tedious and impedes generic

   *  programming.  Using this function lets you take advantage of automatic

   *  template parameter deduction, making the compiler match the correct

   *  types for you.

  */

  template<typename _Container>

    inline front_insert_iterator<_Container>

    front_inserter(_Container& __x)

    { return front_insert_iterator<_Container>(__x); }

  /**

   *  @brief  Turns assignment into insertion.

   *

   *  These are output iterators, constructed from a container-of-T.

   *  Assigning a T to the iterator inserts it in the container at the

   *  %iterator's position, rather than overwriting the value at that

   *  position.

   *

   *  (Sequences will actually insert a @e copy of the value before the

   *  %iterator's position.)

   *

   *  Tip:  Using the inserter function to create these iterators can

   *  save typing.

  */

  template<typename _Container>

    class insert_iterator

    : public iterator<output_iterator_tag, void, void, void, void>

    {

    protected:

      _Container* container;

      typename _Container::iterator iter;

    public:

      /// A nested typedef for the type of whatever container you used.

      typedef _Container          container_type;

      /**

       *  The only way to create this %iterator is with a container and an

       *  initial position (a normal %iterator into the container).

      */

      insert_iterator(_Container& __x, typename _Container::iterator __i)

      : container(&__x), iter(__i) {}

      /**

       *  @param  __value  An instance of whatever type

       *                 container_type::const_reference is; presumably a

       *                 reference-to-const T for container<T>.

       *  @return  This %iterator, for chained operations.

       *

       *  This kind of %iterator maintains its own position in the

       *  container.  Assigning a value to the %iterator will insert the

       *  value into the container at the place before the %iterator.

       *

       *  The position is maintained such that subsequent assignments will

       *  insert values immediately after one another.  For example,

       *  @code

       *     // vector v contains A and Z

       *

       *     insert_iterator i (v, ++v.begin());

       *     i = 1;

       *     i = 2;

       *     i = 3;

       *

       *     // vector v contains A, 1, 2, 3, and Z

       *  @endcode

      */

#if __cplusplus < 201103L

      insert_iterator&

      operator=(typename _Container::const_reference __value)

      {

        iter = container->insert(iter, __value);

        ++iter;

        return *this;

      }

#else

      insert_iterator&

      operator=(const typename _Container::value_type& __value)

      {

        iter = container->insert(iter, __value);

        ++iter;

        return *this;

      }

      insert_iterator&

      operator=(typename _Container::value_type&& __value)

      {

        iter = container->insert(iter, std::move(__value));

        ++iter;

        return *this;

      }

#endif

      /// Simply returns *this.

      insert_iterator&

      operator*()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      insert_iterator&

      operator++()

      { return *this; }

      /// Simply returns *this.  (This %iterator does not @a move.)

      insert_iterator&

      operator++(int)

      { return *this; }

    };

  /**

   *  @param __x  A container of arbitrary type.

   *  @return  An instance of insert_iterator working on @p __x.

   *

   *  This wrapper function helps in creating insert_iterator instances.

   *  Typing the name of the %iterator requires knowing the precise full

   *  type of the container, which can be tedious and impedes generic

   *  programming.  Using this function lets you take advantage of automatic

   *  template parameter deduction, making the compiler match the correct

   *  types for you.

  */

  template<typename _Container, typename _Iterator>

    inline insert_iterator<_Container>

    inserter(_Container& __x, _Iterator __i)

    {

      return insert_iterator<_Container>(__x,

                                         typename _Container::iterator(__i));

    }

  // @} group iterators

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // This iterator adapter is @a normal in the sense that it does not

  // change the semantics of any of the operators of its iterator

  // parameter.  Its primary purpose is to convert an iterator that is

  // not a class, e.g. a pointer, into an iterator that is a class.

  // The _Container parameter exists solely so that different containers

  // using this template can instantiate different types, even if the

  // _Iterator parameter is the same.

  using std::iterator_traits;

  using std::iterator;

  template<typename _Iterator, typename _Container>

    class __normal_iterator

    {

    protected:

      _Iterator _M_current;

      typedef iterator_traits<_Iterator>                __traits_type;

    public:

      typedef _Iterator                                 iterator_type;

      typedef typename __traits_type::iterator_category iterator_category;

      typedef typename __traits_type::value_type        value_type;

      typedef typename __traits_type::difference_type   difference_type;

      typedef typename __traits_type::reference         reference;

      typedef typename __traits_type::pointer           pointer;

      _GLIBCXX_CONSTEXPR __normal_iterator() : _M_current(_Iterator()) { }

      explicit

      __normal_iterator(const _Iterator& __i) : _M_current(__i) { }

      // Allow iterator to const_iterator conversion

      template<typename _Iter>

        __normal_iterator(const __normal_iterator<_Iter,

                          typename __enable_if<

               (std::__are_same<_Iter, typename _Container::pointer>::__value),

                      _Container>::__type>& __i)

        : _M_current(__i.base()) { }

      // Forward iterator requirements

      reference

      operator*() const

      { return *_M_current; }

      pointer

      operator->() const

      { return _M_current; }

      __normal_iterator&

      operator++()

      {

        ++_M_current;

        return *this;

      }

      __normal_iterator

      operator++(int)

      { return __normal_iterator(_M_current++); }

      // Bidirectional iterator requirements

      __normal_iterator&

      operator--()

      {

        --_M_current;