boost/iterator/permutation_iterator.hpp

   1 // (C) Copyright Toon Knapen    2001.
   2 // (C) Copyright David Abrahams 2003.
   3 // (C) Copyright Roland Richter 2003.
   4 // Distributed under the Boost Software License, Version 1.0. (See
   5 // accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_PERMUTATION_ITERATOR_HPP
   9 #define BOOST_PERMUTATION_ITERATOR_HPP
  10
  11 #include <iterator>
  12
  13 #include <boost/iterator/iterator_adaptor.hpp>
  14
  15
  16 namespace boost
  17 {
  18
  19 template< class ElementIterator
  20         , class IndexIterator>
  21 class permutation_iterator
  22   : public iterator_adaptor<
  23              permutation_iterator<ElementIterator, IndexIterator>
  24            , IndexIterator, typename detail::iterator_traits<ElementIterator>::value_type
  25            , use_default, typename detail::iterator_traits<ElementIterator>::reference>
  26 {
  27   typedef iterator_adaptor<
  28             permutation_iterator<ElementIterator, IndexIterator>
  29           , IndexIterator, typename detail::iterator_traits<ElementIterator>::value_type
  30           , use_default, typename detail::iterator_traits<ElementIterator>::reference> super_t;
  31
  32   friend class iterator_core_access;
  33
  34 public:
  35   permutation_iterator() : m_elt_iter() {}
  36
  37   explicit permutation_iterator(ElementIterator x, IndexIterator y)
  38       : super_t(y), m_elt_iter(x) {}
  39
  40   template<class OtherElementIterator, class OtherIndexIterator>
  41   permutation_iterator(
  42       permutation_iterator<OtherElementIterator, OtherIndexIterator> const& r
  43       , typename enable_if_convertible<OtherElementIterator, ElementIterator>::type* = 0
  44       , typename enable_if_convertible<OtherIndexIterator, IndexIterator>::type* = 0
  45       )
  46     : super_t(r.base()), m_elt_iter(r.m_elt_iter)
  47   {}
  48
  49 private:
  50     typename super_t::reference dereference() const
  51         { return *(m_elt_iter + *this->base()); }
  52
  53 #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
  54     template <class,class> friend class permutation_iterator;
  55 #else
  56  public:
  57 #endif
  58     ElementIterator m_elt_iter;
  59 };
  60
  61
  62 template <class ElementIterator, class IndexIterator>
  63 permutation_iterator<ElementIterator, IndexIterator>
  64 make_permutation_iterator( ElementIterator e, IndexIterator i )
  65 {
  66     return permutation_iterator<ElementIterator, IndexIterator>( e, i );
  67 }
  68
  69
  70 } // namespace boost
  71
  72 #endif