C++26 Ranges: Parallel Algorithms and Safer Filters

In part 1 we looked at the new views C++26 adds, and in part 2 we covered the infrastructure improvements. This final part is about the biggest gap in C++20 ranges: you couldn’t run them in parallel. C++17 added execution policies to the classic std:: algorithms, but C++20 ranges never got them. If you wanted parallelism, you had to decompose your ranges pipeline back into iterator pairs. C++26...