1 // Copyright (c) 2015-2018 Daniel Frey
2 // Please see LICENSE for license or visit https://github.com/taocpp/sequences/
3 
4 #ifndef TAO_SEQ_PARTIAL_SUM_HPP
5 #define TAO_SEQ_PARTIAL_SUM_HPP
6 
7 #include <cstddef>
8 #include <utility>
9 
10 #include "make_integer_sequence.hpp"
11 #include "sum.hpp"
12 
13 namespace tao
14 {
15    namespace seq
16    {
17       namespace impl
18       {
19          template< std::size_t, typename S, typename = make_index_sequence< S::size() > >
20          struct partial_sum;
21 
22          template< std::size_t I, typename T, T... Ns, std::size_t... Is >
23          struct partial_sum< I, integer_sequence< T, Ns... >, index_sequence< Is... > >
24             : seq::sum< T, ( ( Is < I ) ? Ns : 0 )... >
25          {
26             static_assert( I <= sizeof...( Is ), "tao::seq::partial_sum<I, S>: I is out of range" );
27          };
28 
29       }  // namespace impl
30 
31       template< std::size_t I, typename T, T... Ns >
32       struct partial_sum
33          : impl::partial_sum< I, integer_sequence< T, Ns... > >
34       {
35       };
36 
37       template< std::size_t I, typename T, T... Ns >
38       struct partial_sum< I, integer_sequence< T, Ns... > >
39          : impl::partial_sum< I, integer_sequence< T, Ns... > >
40       {
41       };
42 
43    }  // namespace seq
44 
45 }  // namespace tao
46 
47 #endif
48