regex-cache

This crate provides a library for caching or lazily creating regular expressions.

Lazy regular expressions are backed by Thread Local Storage, while the regular expression cache is backed by a Least Recently Used cache.

Why not lazy_static!?

lazy_static! is great but it's only usable when you know what your regular expression is.

In some cases you're loading an insane number of regular expressions (looking at you libphonenumber) that you might eventually use but don't actually want to store as String since that makes you lose type information and ease of use.

When to use LazyRegex

When you have a lot of regular expressions you don't want to use instantly and you don't care about having them still allocated after being used.

Since they're backed by Thread Local Storage you also have to keep in mind that they will be compiled again every time the LazyRegex is accessed in a different thread.

If you're passing around the regular expression to newly created threads you might want to use a locked RegexCache instead.

When to use RegexCache

When you want to limit the number of active regular expressions, the RegexCache only keeps around a specified number of actively used regular expressions.

Since it's an LRU cache having a small limit and using a different regular expression every time ends up wasting memory and time for nothing.