# vecmap-rs
[](https://github.com/martinohmann/vecmap-rs/actions?query=workflow%3Aci)
[](https://crates.io/crates/vecmap-rs)
[](https://docs.rs/vecmap-rs)
[](https://opensource.org/licenses/Apache-2.0)
[](https://opensource.org/licenses/MIT)
A vector-based ordered map and set implementation with zero dependencies and
support for `#![no_std]`.
Map keys are not required to be hashable and do not need to form a total order.
Therefore, [`VecMap<K, V>`](https://docs.rs/vecmap-rs/latest/vecmap/map/struct.VecMap.html)
and [`VecSet<T>`](https://docs.rs/vecmap-rs/latest/vecmap/set/struct.VecSet.html)
can be used with key types which neither implement
[`Hash`](https://doc.rust-lang.org/core/hash/trait.Hash.html) nor
[`Ord`](https://doc.rust-lang.org/core/cmp/trait.Ord.html).
Since vecmap-rs is a [`Vec<(K, V)>`](https://doc.rust-lang.org/alloc/vec/struct.Vec.html)
under the hood, worst case lookup and insertion performance is `O(n)` and
scales with the number of map entries. Thus, its main use case are small
collections with unhashable keys.
For key types that implement `Hash` and `Ord` consider using a map or set
implementation with better performance such as
[`HashMap`](https://doc.rust-lang.org/std/collections/struct.HashMap.html)/[`HashSet`](https://doc.rust-lang.org/std/collections/struct.HashSet.html)
and
[`BTreeMap`](https://doc.rust-lang.org/std/collections/struct.BTreeMap.html)/[`BTreeSet`](https://doc.rust-lang.org/std/collections/struct.BTreeSet.html)
from the standard library or popular alternatives like
[`IndexMap`](https://docs.rs/indexmap/latest/indexmap/map/struct.IndexMap.html)/[`IndexSet`](https://docs.rs/indexmap/latest/indexmap/set/struct.IndexSet.html).
## Cargo features
The following features are available:
* `serde`: Provides [`Serialize`](https://docs.rs/serde/latest/serde/ser/trait.Serialize.html)
and [`Deserialize`](https://docs.rs/serde/latest/serde/de/trait.Deserialize.html)
implementations for `VecMap` and `VecSet`. This feature is disabled by
default. Enabling it will pull in `serde` as a dependency.
## License
The source code of vecmap-rs is licensed under either of [Apache License,
Version 2.0](LICENSE-APACHE.md) or [MIT license](LICENSE-MIT) at your option.