C++26 Ranges: Parallel Algorithms and Safer Filters

This article discusses the new features in C++26 related to ranges, focusing on parallel algorithms and the implementation of safer filters. It provides insights into how these features enhance performance and safety in C++ programming.

From the article

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 finally closes this gap - and while it was at it, the committee also fixed a long-standing foot-gun in filter_view that could silently produce undefined behaviour.

P3179R9 brings execution policies to over 50 range algorithms. The syntax is straightforward - the execution policy goes first:

1 2 3 4 5 6 7 std :: vector < int > v = /* ... */ ; std :: ranges :: sort ( std :: execution :: par , v )…

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