1 //! # The Rust core allocation and collections library
3 //! This library provides smart pointers and collections for managing
4 //! heap-allocated values.
6 //! This library, like libcore, normally doesn’t need to be used directly
7 //! since its contents are re-exported in the [`std` crate](../std/index.html).
8 //! Crates that use the `#![no_std]` attribute however will typically
9 //! not depend on `std`, so they’d use this crate instead.
13 //! The [`Box`] type is a smart pointer type. There can only be one owner of a
14 //! [`Box`], and the owner can decide to mutate the contents, which live on the
17 //! This type can be sent among threads efficiently as the size of a `Box` value
18 //! is the same as that of a pointer. Tree-like data structures are often built
19 //! with boxes because each node often has only one owner, the parent.
21 //! ## Reference counted pointers
23 //! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended
24 //! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and
25 //! only allows access to `&T`, a shared reference.
27 //! This type is useful when inherited mutability (such as using [`Box`]) is too
28 //! constraining for an application, and is often paired with the [`Cell`] or
29 //! [`RefCell`] types in order to allow mutation.
31 //! ## Atomically reference counted pointers
33 //! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It
34 //! provides all the same functionality of [`Rc`], except it requires that the
35 //! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself
36 //! sendable while [`Rc<T>`][`Rc`] is not.
38 //! This type allows for shared access to the contained data, and is often
39 //! paired with synchronization primitives such as mutexes to allow mutation of
44 //! Implementations of the most common general purpose data structures are
45 //! defined in this library. They are re-exported through the
46 //! [standard collections library](../std/collections/index.html).
48 //! ## Heap interfaces
50 //! The [`alloc`](alloc/index.html) module defines the low-level interface to the
51 //! default global allocator. It is not compatible with the libc allocator API.
53 //! [`Arc`]: sync/index.html
54 //! [`Box`]: boxed/index.html
55 //! [`Cell`]: ../core/cell/index.html
56 //! [`Rc`]: rc/index.html
57 //! [`RefCell`]: ../core/cell/index.html
59 #![allow(unused_attributes)]
60 #![stable(feature = "alloc", since = "1.36.0")]
61 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/",
62 issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
63 test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]
67 #![warn(deprecated_in_future)]
68 #![warn(missing_docs)]
69 #![warn(missing_debug_implementations)]
70 #![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
71 #![allow(explicit_outlives_requirements)]
72 #![allow(incomplete_features)]
74 #![cfg_attr(not(test), feature(generator_trait))]
75 #![cfg_attr(test, feature(test))]
77 #![feature(allocator_api)]
78 #![feature(allow_internal_unstable)]
79 #![feature(arbitrary_self_types)]
80 #![feature(box_into_raw_non_null)]
81 #![feature(box_patterns)]
82 #![feature(box_syntax)]
83 #![feature(cfg_target_has_atomic)]
84 #![feature(coerce_unsized)]
85 #![feature(const_generic_impls_guard)]
86 #![feature(const_generics)]
87 #![feature(const_in_array_repeat_expressions)]
88 #![feature(cow_is_borrowed)]
89 #![feature(dispatch_from_dyn)]
90 #![feature(core_intrinsics)]
91 #![feature(container_error_extra)]
92 #![feature(dropck_eyepatch)]
93 #![feature(exact_size_is_empty)]
94 #![feature(fmt_internals)]
95 #![feature(fn_traits)]
96 #![feature(fundamental)]
97 #![feature(internal_uninit_const)]
98 #![feature(lang_items)]
101 #![feature(optin_builtin_traits)]
103 #![feature(ptr_internals)]
104 #![feature(ptr_offset_from)]
105 #![feature(rustc_attrs)]
106 #![feature(receiver_trait)]
107 #![feature(slice_from_raw_parts)]
108 #![feature(specialization)]
109 #![feature(staged_api)]
110 #![feature(std_internals)]
111 #![feature(str_internals)]
112 #![feature(trusted_len)]
113 #![feature(try_reserve)]
114 #![feature(unboxed_closures)]
115 #![feature(unicode_internals)]
117 #![feature(unsized_locals)]
118 #![feature(allocator_internals)]
119 #![feature(slice_partition_dedup)]
120 #![feature(maybe_uninit_extra, maybe_uninit_slice)]
121 #![feature(alloc_layout_extra)]
122 #![feature(try_trait)]
123 #![feature(associated_type_bounds)]
125 // Allow testing this library
133 // Module with internal macros used by other modules (needs to be included before other modules).
137 // Heaps provided for low-level allocation strategies
141 // Primitive types using the heaps above
143 // Need to conditionally define the mod from `boxed.rs` to avoid
144 // duplicating the lang-items when building in test cfg; but also need
145 // to allow code to have `use boxed::Box;` declarations.
150 pub use std::boxed::Box;
155 #[cfg(target_has_atomic = "ptr")]
169 pub use core::ops; // RangeFull
173 #[unstable(feature = "liballoc_internals", issue = "0", reason = "implementation detail")]
175 pub use core::format_args;