A collection of unique identifiable elements which retains insertion order, inspired by Pointfree's Swift Identified Collections.
Similar to the standard Vec, the IdentifiedVec maintain their elements in a particular user-specified order. However, unlike Vec, the IdentifiedVec introduce the ability to uniquely identify elements, using a hash table to ensure that no two elements have the same identity, and to efficiently look up elements corresponding to specific identifiers.
IdentifiedVec is a useful alternative to Vec when you need to be able to efficiently access unique elements by a stable identifier. It is also a useful alternative to BTreeSet, where the Ord trait requirement may be too strict, an a useful alternative to HashSet where Hash trait requirement may be too strict.
You can create an identified vec with any element type that implements the Identifiable trait.
extern crate identified_vec;
use identified_vec::{IsIdentifiedVec, IdentifiedVec, Identifiable, IdentifiedVecOf};
use std::cell::RefCell;
#[derive(Eq, PartialEq, Clone, Debug)]
struct User {
id: &'static str,
name: RefCell<&'static str>,
}
impl User {
fn new(id: &'static str, name: &'static str) -> Self {
Self {
id,
name: RefCell::new(name),
}
}
fn name(&self) -> &'static str {
*self.name.borrow()
}
}impl Identifiable for User {
type ID = &'static str;
fn id(&self) -> Self::ID {
self.id
}
}let mut users = IdentifiedVecOf::<User>::from_iter([
User::new("u_42", "Satoshi Nakamoto"),
User::new("u_1337", "Leia Skywalker"),
]);
assert_eq!(
users.get(&"u_42").map(|u| u.name()),
Some("Satoshi Nakamoto")
);
assert_eq!(
users.get_at_index(1).map(|u| u.name()),
Some("Leia Skywalker")
);users.append(User::new("u_237", "Alan Turing"));
assert_eq!(
users.elements(),
[
User::new("u_42", "Satoshi Nakamoto"),
User::new("u_1337", "Leia Skywalker"),
User::new("u_237", "Alan Turing"),
]
.iter()
.collect::<Vec<&User>>()
);
// Element with same ID is not appended:
users.append(User::new("u_42", "Tom Mervolo Dolder"));
assert_eq!(
users.elements(),
[
User::new("u_42", "Satoshi Nakamoto"),
User::new("u_1337", "Leia Skywalker"),
User::new("u_237", "Alan Turing"),
]
.iter()
.collect::<Vec<&User>>()
);// Element with same ID replaces existing if an `update_*` method is used:
// e.g. `update_or_insert`:
users.update_or_insert(User::new("u_42", "Tom Mervolo Dolder"), 0);
assert_eq!(
users.elements(),
[
User::new("u_42", "Tom Mervolo Dolder"),
User::new("u_1337", "Leia Skywalker"),
User::new("u_237", "Alan Turing"),
]
.iter()
.collect::<Vec<&User>>()
);// or `update_or_append`
users.update_or_append(User::new("u_237", "Marie Curie"));
assert_eq!(
users.elements(),
[
User::new("u_42", "Tom Mervolo Dolder"),
User::new("u_1337", "Leia Skywalker"),
User::new("u_237", "Marie Curie"),
]
.iter()
.collect::<Vec<&User>>()
);Or you can provide a closure that describes an element's identity:
let numbers = IdentifiedVec::<u32, u32>::new_identifying_element(|e| *e);None of the std collections BTreeSet and HashSet retain insertion order, Vec retains insertion order, however, it allows for duplicates. So if you want a collection of unique elements (Set-like) that does retain insertion order, IdentifiedVec suits your needs. Even better, the elements does not need to be to impl Hash nor Ord.
This crate has the following Cargo features:
serde: Enables serde serialization support onIdentifiedVecOftype (whichElementimplIdentifiabletrait).id_prim: Get impl of traitIdentifiablefor primitives:i8,..,i128,u8, ...,u128andbool(not so useful, allows for only two elements inIdentifiedVecOf, but who am I to discriminate.)
An identified vec consists of a Vec of IDs keeping insertion order and a HashMap of id-element pairs, for constant time lookup of element given an ID.
Licensed under MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent