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fitzgen / bumpalo

A fast bump allocation arena for Rust
https://docs.rs/bumpalo
Apache License 2.0
1.39k stars 110 forks source link

HashMap using RawTable from hashbrown #54

Closed hansihe closed 4 years ago

hansihe commented 4 years ago

This is a copy/paste of the HashMap implementation from hashbrown.

This depends on https://github.com/rust-lang/hashbrown/pull/133, which adds allocator support to hashbrown's RawTable. Do not merge before this lands.

This is split into two parts:

  1. Add a unstable_core_alloc feature that uses the Alloc trait in std instead of the copied internal version.
  2. Add a collections_hash feature that depends on both the unstable_core_alloc feature and the hashbrown crate. I thought it was best to add a new feature for this since it adds a whole new dependency.

Bikeshedding of the feature names is encouraged. If this is a welcome addition, I would be open to adding HashSet as well, which should require significantly less code.

TethysSvensson commented 4 years ago

I am also doubtful of whether this would actually be useful in practice, since bumpalo is not well-suited for applications in need of frequent re-allocations.

fitzgen commented 4 years ago

Closing this as explained in https://github.com/fitzgen/bumpalo/pull/54#pullrequestreview-332768122

Amanieu commented 4 years ago

I'm happy to accept a PR adding allocator_api support to hashbrown. You can extend your existing PR (https://github.com/rust-lang/hashbrown/pull/133) to add allocator support to the full HashMap API instead of just the internal RawTable API.