litemap

litemap

litemap is a crate providing [LiteMap], a highly simplistic "flat" key-value map based off of a single sorted vector.

The main goal of this crate is to provide a map that is good enough for small sizes, and does not carry the binary size impact of HashMap or BTreeMap.

If binary size is not a concern, [std::collections::BTreeMap] may be a better choice for your use case. It behaves very similarly to [LiteMap] for less than 12 elements, and upgrades itself gracefully for larger inputs.

Performance characteristics

[LiteMap] is a data structure with similar characteristics as [std::collections::BTreeMap] but with slightly different trade-offs as it's implemented on top of a flat storage (e.g. Vec).

• [LiteMap] iteration is generally faster than BTreeMap because of the flat storage.
• [LiteMap] can be pre-allocated whereas BTreeMap can't.
• [LiteMap] has a smaller memory footprint than BTreeMap for small collections (< 20 items).
• Lookup is O(log(n)) like BTreeMap.
• Insertion is generally O(n), but optimized to O(1) if the new item sorts greater than the current items. In BTreeMap it's O(log(n)).
• Deletion is O(n) whereas BTreeMap is O(log(n)).
• Bulk operations like from_iter, extend and deserialization have an optimized O(n) path for inputs that are ordered and O(n*log(n)) complexity otherwise.

Pluggable Backends

By default, [LiteMap] is backed by a Vec; however, it can be backed by any appropriate random-access data store, giving that data store a map-like interface. See the [store] module for more details.

Const construction

[LiteMap] supports const construction from any store that is const-constructible, such as a static slice, via [LiteMap::from_sorted_store_unchecked()]. This also makes [LiteMap] suitable for use with [databake]. See impl Bake for LiteMap for more details.

More Information

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