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>
reduce(InputIterator first,InputIterator last,T init)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
reduce(InputIterator first,InputIterator last)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
reduce(const Range & r)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>
reduce(const Range & r,T init)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
74