boost/accumulators/statistics/times2_iterator.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // times2_iterator.hpp
   3 //
   4 //  Copyright 2006 Eric Niebler. Distributed under the Boost
   5 //  Software License, Version 1.0. (See accompanying file
   6 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_ACCUMULATORS_STATISTICS_TIMES2_ITERATOR_HPP_DE_01_01_2006
   9 #define BOOST_ACCUMULATORS_STATISTICS_TIMES2_ITERATOR_HPP_DE_01_01_2006
  10
  11 #include <functional>
  12 #include <boost/range/begin.hpp>
  13 #include <boost/range/end.hpp>
  14 #include <boost/range/iterator_range.hpp>
  15 #include <boost/iterator/transform_iterator.hpp>
  16 #include <boost/iterator/counting_iterator.hpp>
  17 #include <boost/iterator/permutation_iterator.hpp>
  18
  19 namespace boost { namespace accumulators
  20 {
  21
  22 namespace detail
  23 {
  24     typedef transform_iterator<
  25         std::binder1st<std::multiplies<std::size_t> >
  26       , counting_iterator<std::size_t>
  27     > times2_iterator;
  28
  29     inline times2_iterator make_times2_iterator(std::size_t i)
  30     {
  31         return make_transform_iterator(
  32             make_counting_iterator(i)
  33           , std::bind1st(std::multiplies<std::size_t>(), 2)
  34         );
  35     }
  36
  37
  38     ///////////////////////////////////////////////////////////////////////////////
  39     // lvalue_index_iterator
  40     template<typename Base>
  41     struct lvalue_index_iterator
  42       : Base
  43     {
  44         lvalue_index_iterator(Base base)
  45           : Base(base)
  46         {
  47         }
  48
  49         typename Base::reference operator [](typename Base::difference_type n) const
  50         {
  51             return *(*this + n);
  52         }
  53     };
  54 } // namespace detail
  55
  56 }}
  57
  58 #endif