[−][src]Crate fast_map

A small library and custom derive to create a map-like struct that uses match expressions to get and insert values.

If you know your keys at compile-time, this library will likely be faster than HashMap for supported map operations.

Provides the following operations on the wrapping struct (via derive macros):

MyMap::get, returns Result<Option<&V>, Error>
MyMap::get_mut, returns Result<Option<&mut V>, Error>
MyMap::insert, returns Result<Option<V>, Error>, where V is the old value if one exists
MyMap::remove, returns Result<Option<V>, Error>
MyMap::values, returns an iterator over &Vs

If you know that your operations cannot fail (e.g. if your key type is an enum, and you list all variants as keys), you can add infallible = true to your derive attributes, which will unwrap the result of your map operations.

Usage


fn main() {
    pub enum A { A, B, C, D };

    #[derive(Default, fast_map::FastMap)]
    // We know this cannot fail, since we list all the `enum` variants, so we add `infallible = true`
    #[fast_map(infallible = true, keys(A::A, A::B, A::C, A::D))]
    struct Foo(fast_map::Map4<A, String>);

    let mut foo = Foo::default();

    foo.insert(A::B, "B".into());

    assert_eq!(foo.get(A::B), Some(&"B".to_string()));

    assert_eq!(foo.get(A::C), None);

    foo.insert(A::C, "C".into());

    assert_eq!(foo.values().collect::<Vec<_>>().len(), 2);
}

Changelog

0.2.1

Add the non-erroring operations back as depending on macro attribute (infallible = true). Default is false.

0.2.0

Removed easy and strict MapLike traits. It's better to handle unknown keys explicitly, even for gets.
Added get_mut operation to the wrapping struct

Structs

Map1	Container for a `map` with 1 field
Map2	Container for a `map` with 2 fields
Map3	Container for a `map` with 3 fields
Map4	Container for a `map` with 4 fields
Map5	Container for a `map` with 5 fields
Map6	Container for a `map` with 6 fields
Map7	Container for a `map` with 7 fields
Map8	Container for a `map` with 8 fields
Map9	Container for a `map` with 9 fields
Map10	Container for a `map` with 10 fields
Map11	Container for a `map` with 11 fields
Map12	Container for a `map` with 12 fields
Map13	Container for a `map` with 13 fields
Map14	Container for a `map` with 14 fields
Map15	Container for a `map` with 15 fields
Map16	Container for a `map` with 16 fields
Map17	Container for a `map` with 17 fields
Map18	Container for a `map` with 18 fields
Map19	Container for a `map` with 19 fields
Map20	Container for a `map` with 20 fields
Map21	Container for a `map` with 21 fields
Map22	Container for a `map` with 22 fields
Map23	Container for a `map` with 23 fields
Map24	Container for a `map` with 24 fields
Map25	Container for a `map` with 25 fields
Map26	Container for a `map` with 26 fields
Map27	Container for a `map` with 27 fields
Map28	Container for a `map` with 28 fields
Map29	Container for a `map` with 29 fields
Map30	Container for a `map` with 30 fields
Map31	Container for a `map` with 31 fields
Map32	Container for a `map` with 32 fields
Map48	Container for a `map` with 48 fields
Map64	Container for a `map` with 64 fields
Values	Iterator over existing values

Enums

Error

Currently just KeyNotFound

Derive Macros

FastMap