9 releases
0.2.1 | Jan 16, 2020 |
---|---|
0.2.0 | Jan 16, 2020 |
0.1.6 | Oct 8, 2019 |
#2255 in Rust patterns
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11KB
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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
, returnsResult<Option<&V>, Error>
MyMap::get_mut
, returnsResult<Option<&mut V>, Error>
MyMap::insert
, returnsResult<Option<V>, Error>
, whereV
is the old value if one existsMyMap::remove
, returnsResult<Option<V>, Error>
MyMap::values
, returns an iterator over&V
s
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 isfalse
.
0.2.0
- Removed
easy
andstrict
MapLike
traits. It's better to handle unknown keys explicitly, even forget
s. - Added
get_mut
operation to the wrapping struct
Current version: 0.2.1
License: MIT
Dependencies
~1.5MB
~36K SLoC