A very easy to use library for interning strings or other data in rust. Interned data is very efficient to either hash or compare for equality (just a pointer comparison). Data is also automatically de-duplicated.
You have two options with the internment crate:
Intern, which will never free your data. This means that an
Intern is Copy, so you can make as many copies of the pointer
as you may care to at no cost.
ArcIntern, which reference-counts your data and frees it when
there are no more references. ArcIntern will keep memory use
down, but requires locking whenever a clone of your pointer is
made, as well as when dropping the pointer.
In both cases, accessing your data is a single pointer
dereference, and the size of either Intern or ArcIntern is a
single pointer. In both cases, you have a guarantee that a single
data value (as defined by Eq and Hash) will correspond to a
single pointer value. This means that we can use pointer
comparison (and a pointer hash) in place of value comparisons,
which is very fast.
rust
use internment::Intern;
let x = Intern::new("hello");
let y = Intern::new("world");
assert_ne!(x, y);