Crate alloc [] [src]

🔬 This is a nightly-only experimental API. (alloc #27783)

this library is unlikely to be stabilized in its current form or name

The Rust core allocation and collections library

This library provides smart pointers and collections for managing heap-allocated values.

This library, like libcore, is not intended for general usage, but rather as a building block of other libraries. The types and interfaces in this library are re-exported through the standard library, and should not be used through this library.

Boxed values

The Box type is a smart pointer type. There can only be one owner of a Box, and the owner can decide to mutate the contents, which live on the heap.

This type can be sent among threads efficiently as the size of a Box value is the same as that of a pointer. Tree-like data structures are often built with boxes because each node often has only one owner, the parent.

Reference counted pointers

The Rc type is a non-threadsafe reference-counted pointer type intended for sharing memory within a thread. An Rc pointer wraps a type, T, and only allows access to &T, a shared reference.

This type is useful when inherited mutability (such as using Box) is too constraining for an application, and is often paired with the Cell or RefCell types in order to allow mutation.

Atomically reference counted pointers

The Arc type is the threadsafe equivalent of the Rc type. It provides all the same functionality of Rc, except it requires that the contained type T is shareable. Additionally, Arc<T> is itself sendable while Rc<T> is not.

This type allows for shared access to the contained data, and is often paired with synchronization primitives such as mutexes to allow mutation of shared resources.


Implementations of the most common general purpose data structures are defined in this library. They are re-exported through the standard collections library.

Heap interfaces

The heap module defines the low-level interface to the default global allocator. It is not compatible with the libc allocator API.


pub use binary_heap::BinaryHeap;
pub use btree_map::BTreeMap;
pub use btree_set::BTreeSet;
pub use linked_list::LinkedList;
pub use vec_deque::VecDeque;
pub use string::String;
pub use vec::Vec;



Thread-safe reference-counting pointers.


A priority queue implemented with a binary heap.


A module for working with borrowed data.


A pointer type for heap allocation.


A map based on a B-Tree.


A set based on a B-Tree.


Utilities for formatting and printing Strings.


A doubly-linked list with owned nodes.


Single-threaded reference-counting pointers. 'Rc' stands for 'Reference Counted'.


A dynamically-sized view into a contiguous sequence, [T].


Unicode string slices.


A UTF-8 encoded, growable string.


A contiguous growable array type with heap-allocated contents, written Vec<T>.


A double-ended queue implemented with a growable ring buffer.

allocator [
heap [
raw_vec [



Creates a String using interpolation of runtime expressions.


Creates a Vec containing the arguments.