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

   1 /*
   2    Copyright (c) Marshall Clow 2017.
   3
   4    Distributed under the Boost Software License, Version 1.0. (See accompanying
   5    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 */
   7
   8 /// \file  reduce.hpp
   9 /// \brief Combine the elements of a sequence into a single value
  10 /// \author Marshall Clow
  11
  12 #ifndef BOOST_ALGORITHM_REDUCE_HPP
  13 #define BOOST_ALGORITHM_REDUCE_HPP
  14
  15 #include <functional>     // for std::plus
  16 #include <iterator>       // for std::iterator_traits
  17
  18 #include <boost/config.hpp>
  19 #include <boost/range/begin.hpp>
  20 #include <boost/range/end.hpp>
  21 #include <boost/range/value_type.hpp>
  22
  23 namespace boost { namespace algorithm {
  24
  25 template<class InputIterator, class T, class BinaryOperation>
  26 T reduce(InputIterator first, InputIterator last, T init, BinaryOperation bOp)
  27 {
  28     ;
  29     for (; first != last; ++first)
  30         init = bOp(init, *first);
  31     return init;
  32 }
  33
  34 template<class InputIterator, class T>
  35 T reduce(InputIterator first, InputIterator last, T init)
  36 {
  37         typedef typename std::iterator_traits<InputIterator>::value_type VT;
  38     return boost::algorithm::reduce(first, last, init, std::plus<VT>());
  39 }
  40
  41 template<class InputIterator>
  42 typename std::iterator_traits<InputIterator>::value_type
  43 reduce(InputIterator first, InputIterator last)
  44 {
  45     return boost::algorithm::reduce(first, last,
  46        typename std::iterator_traits<InputIterator>::value_type());
  47 }
  48
  49 template<class Range>
  50 typename boost::range_value<Range>::type
  51 reduce(const Range &r)
  52 {
  53     return boost::algorithm::reduce(boost::begin(r), boost::end(r));
  54 }
  55
  56 //      Not sure that this won't be ambiguous (1)
  57 template<class Range, class T>
  58 T reduce(const Range &r, T init)
  59 {
  60     return boost::algorithm::reduce(boost::begin (r), boost::end (r), init);
  61 }
  62
  63
  64 //      Not sure that this won't be ambiguous (2)
  65 template<class Range, class T, class BinaryOperation>
  66 T reduce(const Range &r, T init, BinaryOperation bOp)
  67 {
  68     return boost::algorithm::reduce(boost::begin(r), boost::end(r), init, bOp);
  69 }
  70
  71 }} // namespace boost and algorithm
  72
  73 #endif // BOOST_ALGORITHM_REDUCE_HPP