text: ///////////////////////////////////////////////////////////////////////////////
  // times2_iterator.hpp
  //
  //  Copyright 2006 Eric Niebler. Distributed under the Boost
  //  Software License, Version 1.0. (See accompanying file
  //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  
  #ifndef BOOST_ACCUMULATORS_STATISTICS_TIMES2_ITERATOR_HPP_DE_01_01_2006
  #define BOOST_ACCUMULATORS_STATISTICS_TIMES2_ITERATOR_HPP_DE_01_01_2006
  
  #include <functional>
  #include <boost/detail/workaround.hpp>
  #include <boost/range/begin.hpp>
  #include <boost/range/end.hpp>
  #include <boost/range/iterator_range.hpp>
  #include <boost/iterator/transform_iterator.hpp>
  #include <boost/iterator/counting_iterator.hpp>
  #include <boost/iterator/permutation_iterator.hpp>
  
  namespace boost { namespace accumulators
  {
  
  namespace detail
  {
      typedef transform_iterator<
          std::binder1st<std::multiplies<std::size_t> >
        , counting_iterator<std::size_t>
      > times2_iterator;
  
      inline times2_iterator make_times2_iterator(std::size_t i)
      {
          return make_transform_iterator(
              make_counting_iterator(i)
            , std::bind1st(std::multiplies<std::size_t>(), 2)
          );
      }
  
      ///////////////////////////////////////////////////////////////////////////////
      // lvalue_index_iterator
      template<typename Base>
      struct lvalue_index_iterator
        : Base
      {
          lvalue_index_iterator()
            : Base()
          {}
  
          lvalue_index_iterator(Base base)
            : Base(base)
          {
          }
  
          typename Base::reference operator [](typename Base::difference_type n) const
          {
              return *(*this + n);
          }
      };
  } // namespace detail
  
  }}
  
  #endif
  