C++ High Performance

Combining std::for_each with linear range

What we can do instead is to combine std::for_each() with the LinearRange class described in Chapter 5, A Deeper Look at Iterators. To remind you, the LinearRange class is constructed via the function make_linear_range() which returns a range of numbers that can be iterated just like a regular container.

An index-based for-loop based on an STL algorithm can be created like this:

auto first_idx = size_t{0}; 
auto last_idx = mice.size(); 
auto indices = make_linear_range(first_idx, last_idx, last_idx); 
std::for_each(indices.begin(), indices.end(), [&mice](size_t i){ 
  std::cout << i << " " << mice[i] << '\n'; 
}); 

This can then be further parallelized with an execution policy of choice:

auto p = std::execution::par; ...