devel/frozen 1.2.0

Frozen is a header-only library that provides 0 cost initialization for immutable containers, fixed-size containers, and various algorithms.

Frozen provides:

• immutable (a.k.a. frozen), constexpr-compatible versions of std::set, std::unordered_set, std::map and std::unordered_map.
• fixed-capacity, constinit-compatible versions of std::map and std::unordered_map with immutable, compile-time selected keys mapped to mutable values.
• 0-cost initialization version of std::search for frozen needles using Boyer-Moore or Knuth-Morris-Pratt algorithms.

The unordered_* containers are guaranteed perfect (a.k.a. no hash collision) and the extra storage is linear with respect to the number of keys.

Once initialized, the container keys cannot be updated, and in exchange, lookups are faster. And initialization is free when constexpr or constinit is used :-).