Expand description
Different reference kinds in Rust.
This crate provides 2 kinds of reference: immutable and mutable.
All of them represented in one enum RefKind
, which allows to store immutable and mutable references together.
But the most importantly, this crate allows to retrieve many mutable references out of the collection by creating a new collection which holds these references.
For that very case, crate defines some useful traits:
MoveRef
andMoveMut
for containers to retrieve corresponding kind of reference,Move
as a combination of the traits above,Many
for collections which is implemented for peekable iterators, slices and so on.
But nothing stops you to implement these traits for other types as well!
Example
use core::array;
use ref_kind::{Many, RefKind, MoveError};
// Create an array of square of integers from 0 to 9
let mut array: [_; 10] = array::from_fn(|i| i * i);
// Create collection of mutable references on all of the array elements
let mut many: [_; 10] = array
.iter_mut()
.map(|sq| Some(RefKind::from(sq)))
.collect::<Vec<_>>()
.try_into()
.unwrap();
// Move out mutable reference by index 1
// It is no longer in the `many`
let one = many.move_mut(1).unwrap();
assert_eq!(*one, 1);
// Move out immutable reference by index 4
// `many` now contains immutable reference, not mutable one
let four = many.move_ref(4).unwrap();
assert_eq!(*four, 16);
// Move it again: no panic here because immutable reference was copied
let four_again = many.move_ref(4).unwrap();
assert_eq!(four, four_again);
// This call will return an error because `many` contains no reference by index 1
let one_again = many.try_move_ref(1);
assert_eq!(one_again, Err(MoveError::BorrowedMutably));
#![no_std]
support
This crate is a no_std
crate. It depends only on the core
crate.
std
feature of the crate is enabled by default, so to use it in no_std
environment,
you should disable default features of this crate in Cargo.toml:
[dependencies]
ref_kind = { version = "0.5.0", default-features = false }
#![forbid(unsafe_code)]
This crate contains no unsafe
code.
Flags
This crate has the following Cargo features:
Feature name | Description |
---|---|
alloc | Implements Many trait for VecDeque and BTreeMap in alloc crate |
std | Implements Many trait for HashMap in standard library, depends on alloc feature |
hashbrown | Implements Many trait for HashMap in hashbrown crate |
Feature std
is enabled by default.
You can disable it by using default-features = false
in Cargo.toml.
These features were added to this crate to make it usable
with common Rust collections, such as Vec
and HashMap
.
Re-exports
Modules
Enums
- Enum that defines errors which can occur when moving reference out of the value.
Traits
- Trait for collections which hold different kinds of reference.
- Trait for containers which hold different kinds of reference.
- Trait for containers which hold mutable kind of reference.
- Trait for containers which hold immutable kind of reference.
Type Definitions
- The result of moving reference out of the value.