What one element of a cache key must support: equality, hashing, and being copyable — the key is copied into a tuple and again into the map. Element-wise on purpose: TupleHash's operator() takes any tuple and fails inside its body, so constraining it would constrain nothing. More...

#include <cache.hpp>

Concept definition

template<typename T>
concept util::cache::CacheKeyElement =  std::equality_comparable<T>
                      and std::default_initializable<std::hash<T>>
                      and std::invocable<std::hash<T>&, const T&>
                      and std::copy_constructible<T>

Detailed Description

What one element of a cache key must support: equality, hashing, and being copyable — the key is copied into a tuple and again into the map. Element-wise on purpose: TupleHash's operator() takes any tuple and fails inside its body, so constraining it would constrain nothing.