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?

use lookups::{collections::LkupHashMap, lookup::index::UniquePosIndex};

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

// create a new Lookup HashMap: LkupMap with a UniquePosIndex
let mut map = LkupHashMap::<UniquePosIndex<usize, String>, _, _, _>::new(|c: &Car| c.id);
map.insert(String::from("BMW"),  Car{id: 0, name: "BMW".into()});
map.insert(String::from("Audi"), Car{id: 5, name: "Audi".into()});
map.insert(String::from("VW"),   Car{id: 2, name: "VW".into()});

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

// get a Car by an given Key
assert_eq!(map.lkup().get_by_key(5).next(), Some(&Car{id: 5, name: "Audi".into()}));
assert_eq!((map.lkup().min_key(), map.lkup().max_key()), (Some(0), Some(5)));

// create a View: a subset from the Lookups (defined by the given Keys)
let view = map.create_lkup_view([0, 2]);

assert_eq!(view.get_by_key(0).next(), Some(&Car{id: 0, name: "BMW".into()}));
assert_eq!((view.min_key(), view.max_key()), (Some(0), Some(2)));