The Rust core allocation and collections library
This library provides smart pointers and collections for managing heap-allocated values.
This library, like core, normally doesn’t need to be used directly
since its contents are re-exported in the
Crates that use the
#![no_std] attribute however will typically
not depend on
std, so they’d use this crate instead.
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
This type can be sent among threads efficiently as the size of a
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
Rc type is a non-threadsafe reference-counted pointer type intended
for sharing memory within a thread. An
Rc pointer wraps a type,
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
RefCell types in order to allow mutation.
Atomically reference counted pointers
Arc type is the threadsafe equivalent of the
Rc type. It
provides all the same functionality of
Rc, except it requires that the
T is shareable. Additionally,
Arc<T> is itself
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.
alloc module defines the low-level interface to the
default global allocator. It is not compatible with the libc allocator API.
Box<T>type for heap allocation.