exclusive_scan_left() [1/2]

template<typename Function , product_type T, typename Value >

constexpr auto kumi::exclusive_scan_left ( Function &&  f, T &&  t, Value  init  )

inlineconstexpr

Computes the exclusive prefix scan of all elements of a product type using a tail recursive call.

Note

The first stored value is the provided initial value.

Parameters

f	Binary callable function to apply
t	Product type to operate on
init	Optional initial value of the scan

Returns

A tuple of prefix partial accumulations where each element 'I' equals f( f( f(init, get<0>(t)), ...), get<I-1>(t))

Helper type

namespace kumi::result
{
  template<typename Function, product_type Tuple, typename Value> struct exclusive_scan_left;
 
  template<typename Function, product_type Tuple, typename Value>
  using exclusive_scan_left_t = typename exclusive_scan_left<Function,Tuple,Value>::type;
}

Computes the return type of a call to kumi::exclusive_scan_left

Example

 
#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  auto t = kumi::tuple{2.,1,short{55},'z'};
 
  auto output = kumi::exclusive_scan_left( [](auto acc, auto elt) 
                  { 
                    return acc + sizeof(elt); 
                  }
                  , t
                  , std::size_t{42}                
                );
 
  std::cout << output << "\n"; 
 
  auto u = kumi::tuple{1,3,2,4,0,5,9,6,7};
 
  std::cout << kumi::exclusive_scan_left(kumi::function::plus, u) << "\n";
}