Enum Collections for Rust

Enum Map is a special case of a Hash Map, with better computational complexity guarantees and overall performance.

Usage

EnumMap

EnumMap 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.

Using get and insert functions.

 use enum_collections::{enum_collections, 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));
 map.remove(Letter::A);
 assert_eq!(None, map.get(Letter::A));

Using Index and IndexMut syntactic sugar.

use enum_collections::{enum_collections, EnumMap, Enumerated};
#[enum_collections]
enum Letter {
    A,
    B,
}

let mut map: EnumMap<Letter, u8> = EnumMap::new();
map[Letter::A] = Some(42);
assert_eq!(Some(42u8), map[Letter::A]);
assert_eq!(Some(&42u8), map[Letter::A].as_ref());

EnumTable

EnumTable 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.

Using Index and IndexMut syntactic sugar.

 use enum_collections::{enum_collections, EnumTable, Enumerated};
 #[enum_collections]
 enum Letter {
     A,
     B,
 }

 let mut map: EnumTable<Letter, u8> = EnumTable::new();
 map[Letter::A] = 42;
 assert_eq!(42u8, map[Letter::A]);
 assert_eq!(u8::default(), map[Letter::B]);

Using get and insert functions.

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. Invoke cargo bench to run them.

EnumMap

NAME                                     lower bound | est | upper bound
EnumMap get                      time:   [635.02 ps 635.52 ps 636.06 ps] est ~22x faster
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

NAME                                             lower bound | est | upper bound
EnumTable Index get                      time:   [460.22 ps 460.81 ps 461.41 ps] est ~1.113x faster
Crate Enum-Map Index get                 time:   [512.16 ps 512.62 ps 513.13 ps]

EnumTable IndexMut insert                time:   [746.66 ps 747.67 ps 748.79 ps] est ~0.943x speed
Crate Enum-Map insert                    time:   [704.81 ps 705.35 ps 705.92 ps] est ~1.057x faster