# Enum Collections for Rust
[](https://github.com/Pscheidl/enum-map/actions/workflows/rust.yml)
Enum Map is a special case of a Hash Map, with better **computational complexity** guarantees and overall **performance**.
## Usage
### EnumMap
Enum Map is a special case of a Hash Map, with better **computational complexity** guarantees and overall **performance**. Can differentiante between a missing (`Option::None`)
and set (`Option::Some`) value.
```rust
use enum_collections::{enummap, EnumMap, Enumerated};
#[enum_collections]
enum Letter {
A,
B,
}
let mut map: EnumMap<Letter, u8> = EnumMap::new();
map.insert(Letter::A, 42);
assert_eq!(Some(&42u8), map.get(Letter::A))
```
### EnumTable
Enum Map is a special case of a Hash Map, with better **computational complexity** guarantees and overall **performance**. Initialized with default values, can NOT differentiate between missing values
and values actually set.
```rust
use enum_collections::{enum_collections, EnumTable, Enumerated};
#[enum_collections]
enum Letter {
A,
B,
}
let mut map: EnumTable<Letter, u8> = EnumTable::new();
map.insert(Letter::A, 42);
assert_eq!(&42u8, map.get(Letter::A));
assert_eq!(&u8::default(), map.get(Letter::B));
```
## Benchmarks
There are single-threaded benchmarks for the `get`, `insert` and `remove` operations in [enum-collections/benches](enum-collections/benches/). Invoke `cargo bench` to run them.
### EnumMap
```
std::collections::HashMap get time: [13.971 ns 13.986 ns 14.002 ns]
EnumMap insert time: [947.20 ps 947.83 ps 948.52 ps] est ~14,7x faster
std::collections::HashMap insert time: [13.938 ns 13.964 ns 13.994 ns]
EnumMap remove time: [481.07 ps 481.79 ps 482.53 ps] est ~28,55x faster
std::collections::HashMap remove time: [13.704 ns 13.737 ns 13.771 ns]
```
### EnumTable
```
Crate Enum-Map get time: [465.44 ps 465.93 ps 466.43 ps]
EnumTable insert time: [676.44 ps 677.17 ps 677.92 ps] est ~0.956x faster
Crate Enum-Map insert time: [645.98 ps 647.60 ps 649.35 ps]
```