Lookups

Improve the data retrieval operations for collections.

Overview

lookups is a crate for extending already existing collections (std::vec::Vec, std::collections::HashMap, ...) with additional lookup functionalities, so you have a faster access to your data as with an iterator or a search algorithm. This wrapper is just as easy to use as the given (original) collection.

The fast access can be achieved by using different methods, like;

• hash tables
• indexing
• ...

Disadvantage

• it is more memory required. In addition to the user data, data for the hash, index are also stored.
• the write operation are slower, because for every wirte operation is an another one (for storing the lookup data) necessary

How can I use it?

#[derive(PartialEq, Debug)]
struct Car {
    id: usize,
    name: String,
}

let cars = [
    (String::from("BMW"),  Car{id: 0, name: "BMW".into()}),
    (String::from("Audi"), Car{id: 5, name: "Audi".into()}),
    (String::from("VW"),   Car{id: 2, name: "VW".into()}),
];

use lookups::{collections::ro::LHashMap, lookup::UniqueIndexLookup};

// create a new Lookup HashMap: LHashMap with a UniqueIndex
let map = LHashMap::<UniqueIndexLookup<_, _>, _, _>::new(|c| c.id, cars);

assert!(map.contains_key("VW"));       // conventionally HashMap access with Key (String)
assert!(map.lkup().contains_key(2));   // lookup with Key (id: usize)

assert_eq!(
    &Car{id: 5, name: "Audi".into()},
    // get a Car by an given Key
    map.lkup().get_by_key(5).next().unwrap()
);

assert_eq!(
    vec![&Car{id: 0, name: "BMW".into()}, &Car{id: 2, name: "VW".into()}],
    // get many Cars by given many Keys
    map.lkup().get_by_many_keys([0, 2]).collect::<Vec<_>>(),
);