Crate rt_map

Runtime managed mutable borrowing from a map.

This library provides a map that allows mutable borrows to different entries at the same time. For a map implementation of this, see rt_vec.

The implementation is extracted and slightly modified from shred.

Usage

Add the following to Cargo.toml

rt_map = "0.6.0" # or
rt_map = { version = "0.6.0", features = ["unsafe_debug"] }

In code:

use rt_map::RtMap;

struct A(u32);

let mut rt_map = RtMap::new();

rt_map.insert('a', A(1));
rt_map.insert('b', A(2));

// We can validly have two mutable borrows from the `RtMap` map!
let mut a = rt_map.borrow_mut(&'a');
let mut b = rt_map.borrow_mut(&'b');
a.0 = 2;
b.0 = 3;

// We need to explicitly drop the A and B borrows, because they are runtime
// managed borrows, and rustc doesn't know to drop them before the immutable
// borrows after this.
drop(a);
drop(b);

// Multiple immutable borrows to the same value are valid.
let a_0 = rt_map.borrow(&'a');
let _a_1 = rt_map.borrow(&'a');
let b = rt_map.borrow(&'b');

println!("A: {}", a_0.0);
println!("B: {}", b.0);

// Trying to mutably borrow a value that is already borrowed (immutably
// or mutably) returns `Err`.
let a_try_borrow_mut = rt_map.try_borrow_mut(&'a');
let exists = if a_try_borrow_mut.is_ok() {
    "Ok(..)"
} else {
    "Err"
};
println!("a_try_borrow_mut: {}", exists); // prints "Err"

Features

"unsafe_debug"

Enables the "unsafe_debug" feature of rt_ref.

See Also

• anymap: Map of any type, without multiple mutable borrows.
• resman: Map of any type, with runtime managed borrowing.
• shred: Contains RtMap type, plus a task dispatcher.

Structs

Cell

A custom cell container that is a RefCell with thread-safety.

CellRef

An immutable reference to data in a Cell.

CellRefMut

A mutable reference to data in a Cell.

Entry

Ref

Reference to a value.

RefMut

Mutable reference to a value.

RtMap

Map from TypeId to type.

Enums

BorrowFail

Failures to borrow a value.