ceph/src/boost/boost/algorithm/cxx17/transform_reduce.hpp

   1 /*
   2    Copyright (c) Marshall Clow 2017.
   3
   4    Distributed under the Boost Software License, Version 1.0. (See accompanying
   5    file LICENSE10.txt or copy at http://www.boost.org/LICENSE10.txt)
   6 */
   7
   8 /// \file  transform_reduce.hpp
   9 /// \brief Combine the (transformed) elements of a sequence (or two) into a single value.
  10 /// \author Marshall Clow
  11
  12 #ifndef BOOST_ALGORITHM_TRANSFORM_REDUCE_HPP
  13 #define BOOST_ALGORITHM_TRANSFORM_REDUCE_HPP
  14
  15 #include <functional>     // for std::plus
  16 #include <iterator>       // for std::iterator_traits
  17
  18 #include <boost/range/begin.hpp>
  19 #include <boost/range/end.hpp>
  20 #include <boost/range/value_type.hpp>
  21
  22 namespace boost { namespace algorithm {
  23
  24 template<class InputIterator1, class InputIterator2, class T,
  25          class BinaryOperation1, class BinaryOperation2>
  26 T transform_reduce(InputIterator1 first1, InputIterator1 last1,
  27                    InputIterator2 first2, T init,
  28                  BinaryOperation1 bOp1, BinaryOperation2 bOp2)
  29 {
  30     for (; first1 != last1; ++first1, (void) ++first2)
  31         init = bOp1(init, bOp2(*first1, *first2));
  32     return init;
  33 }
  34
  35 template<class InputIterator, class T,
  36          class BinaryOperation, class UnaryOperation>
  37 T transform_reduce(InputIterator first, InputIterator last,
  38                    T init, BinaryOperation bOp, UnaryOperation uOp)
  39 {
  40     for (; first != last; ++first)
  41         init = bOp(init, uOp(*first));
  42     return init;
  43 }
  44
  45 template<class InputIterator1, class InputIterator2, class T>
  46 T transform_reduce(InputIterator1 first1, InputIterator1 last1,
  47                    InputIterator2 first2, T init)
  48 {
  49     return transform_reduce(first1, last1, first2, init,
  50                             std::plus<T>(), std::multiplies<T>());
  51 }
  52
  53 }} // namespace boost and algorithm
  54
  55 #endif // BOOST_ALGORITHM_TRANSFORM_REDUCE_HPP