stl_iterator_base_funcs.h File Reference

#include <bits/concept_check.h>
#include <debug/debug.h>

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Functions
namespace std	_GLIBCXX_VISIBILITY (default)

Detailed Description

This is an internal header file, included by other library headers. Do not attempt to use it directly. {iterator}

This file contains all of the general iterator-related utility functions, such as distance() and advance().

Function Documentation

namespace std _GLIBCXX_VISIBILITY

(

default

)

A generalization of pointer arithmetic.

Parameters

__first	An input iterator.
__last	An input iterator.

Returns

The distance between them.

Returns n such that __first + n == __last. This requires that __last must be reachable from __first. Note that n may be negative.

For random access iterators, this uses their + and - operations and are constant time. For other iterator classes they are linear time.

A generalization of pointer arithmetic.

Parameters

__i	An input iterator.
__n	The delta by which to change __i.

Returns

Nothing.

This increments i by n. For bidirectional and random access iterators, __n may be negative, in which case __i is decremented.

For random access iterators, this uses their + and - operations and are constant time. For other iterator classes they are linear time.

{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  template<typename _InputIterator>
    inline typename iterator_traits<_InputIterator>::difference_type
    __distance(_InputIterator __first, _InputIterator __last,
               input_iterator_tag)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      typename iterator_traits<_InputIterator>::difference_type __n = 0;
      while (__first != __last)
    {
      ++__first;
      ++__n;
    }
      return __n;
    }

  template<typename _RandomAccessIterator>
    inline typename iterator_traits<_RandomAccessIterator>::difference_type
    __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
               random_access_iterator_tag)
    {
      // concept requirements
      __glibcxx_function_requires(_RandomAccessIteratorConcept<
                  _RandomAccessIterator>)
      return __last - __first;
    }

  template<typename _InputIterator>
    inline typename iterator_traits<_InputIterator>::difference_type
    distance(_InputIterator __first, _InputIterator __last)
    {
      // concept requirements -- taken care of in __distance
      return std::__distance(__first, __last,
                 std::__iterator_category(__first));
    }

  template<typename _InputIterator, typename _Distance>
    inline void
    __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
    {
      // concept requirements
      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
      _GLIBCXX_DEBUG_ASSERT(__n >= 0);
      while (__n--)
    ++__i;
    }

  template<typename _BidirectionalIterator, typename _Distance>
    inline void
    __advance(_BidirectionalIterator& __i, _Distance __n,
          bidirectional_iterator_tag)
    {
      // concept requirements
      __glibcxx_function_requires(_BidirectionalIteratorConcept<
                  _BidirectionalIterator>)
      if (__n > 0)
        while (__n--)
      ++__i;
      else
        while (__n++)
      --__i;
    }

  template<typename _RandomAccessIterator, typename _Distance>
    inline void
    __advance(_RandomAccessIterator& __i, _Distance __n,
              random_access_iterator_tag)
    {
      // concept requirements
      __glibcxx_function_requires(_RandomAccessIteratorConcept<
                  _RandomAccessIterator>)
      __i += __n;
    }

  template<typename _InputIterator, typename _Distance>
    inline void
    advance(_InputIterator& __i, _Distance __n)
    {
      // concept requirements -- taken care of in __advance
      typename iterator_traits<_InputIterator>::difference_type __d = __n;
      std::__advance(__i, __d, std::__iterator_category(__i));
    }

#if __cplusplus >= 201103L

  template<typename _ForwardIterator>
    inline _ForwardIterator
    next(_ForwardIterator __x, typename
     iterator_traits<_ForwardIterator>::difference_type __n = 1)
    {
      std::advance(__x, __n);
      return __x;
    }

  template<typename _BidirectionalIterator>
    inline _BidirectionalIterator
    prev(_BidirectionalIterator __x, typename
     iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 
    {
      std::advance(__x, -__n);
      return __x;
    }

#endif // C++11

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace