[amelius]

How are you going to garbage collect inside your array? Sounds like you are just evading the problem and reinventing the heap.

[burntsushi]

Not easily. But not all use cases require it. The regex crate makes heavy use of this pattern for finite machine states, for example. But this fits nicely with an arena allocation pattern, so everything can just be dropped at once.

Despite this, it's one of the fastest regex engines around: https://github.com/BurntSushi/rebar#summary-of-search-time-b...

Here's a related but more isolated analysis: https://github.com/burntsushi/rsc-regexp

[amelius]

You could probably make an even faster regex by JIT-compiling the resulting automaton.

[burntsushi]

The benchmarks I linked include multiple regex engines with JITs.

[oconnor663]

I'm not sure whether this is exactly what you mean, but when you need to support deletions you can switch to a "generational" collection like Slab or SlotMap. Your indexes are still integers, but under the covers some of the bits get repurposed to disambiguate new elements that reuse old slots.