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.
55 //! [`Cell`]: core::cell
57 //! [`RefCell`]: core::cell
59 #![allow(unused_attributes)]
60 #![stable(feature = "alloc", since = "1.36.0")]
62 html_root_url = "https://doc.rust-lang.org/nightly/",
63 html_playground_url = "https://play.rust-lang.org/",
64 issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
65 test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
69 #![warn(deprecated_in_future)]
70 #![warn(missing_docs)]
71 #![warn(missing_debug_implementations)]
72 #![allow(explicit_outlives_requirements)]
73 #![allow(incomplete_features)]
74 #![deny(unsafe_op_in_unsafe_fn)]
75 #![cfg_attr(not(test), feature(generator_trait))]
76 #![cfg_attr(test, feature(test))]
77 #![feature(allocator_api)]
78 #![feature(array_chunks)]
79 #![feature(array_windows)]
80 #![feature(allow_internal_unstable)]
81 #![feature(arbitrary_self_types)]
82 #![feature(box_patterns)]
83 #![feature(box_syntax)]
84 #![feature(btree_drain_filter)]
85 #![feature(cfg_sanitize)]
86 #![feature(cfg_target_has_atomic)]
87 #![feature(coerce_unsized)]
88 #![feature(const_btree_new)]
89 #![feature(const_generics)]
90 #![feature(const_in_array_repeat_expressions)]
91 #![feature(cow_is_borrowed)]
92 #![feature(deque_range)]
93 #![feature(dispatch_from_dyn)]
94 #![feature(core_intrinsics)]
95 #![feature(container_error_extra)]
96 #![feature(dropck_eyepatch)]
97 #![feature(exact_size_is_empty)]
98 #![feature(exclusive_range_pattern)]
99 #![feature(extend_one)]
100 #![feature(fmt_internals)]
101 #![feature(fn_traits)]
102 #![feature(fundamental)]
103 #![feature(inplace_iteration)]
104 #![feature(lang_items)]
105 #![feature(layout_for_ptr)]
107 #![feature(map_first_last)]
108 #![feature(map_into_keys_values)]
109 #![feature(maybe_uninit_ref)]
110 #![feature(negative_impls)]
111 #![feature(never_type)]
112 #![feature(new_uninit)]
114 #![feature(nonnull_slice_from_raw_parts)]
115 #![feature(optin_builtin_traits)]
116 #![feature(or_patterns)]
118 #![feature(ptr_internals)]
119 #![feature(raw_ref_op)]
120 #![feature(rustc_attrs)]
121 #![feature(receiver_trait)]
122 #![feature(min_specialization)]
123 #![feature(slice_check_range)]
124 #![feature(slice_ptr_get)]
125 #![feature(slice_ptr_len)]
126 #![feature(staged_api)]
127 #![feature(std_internals)]
128 #![feature(str_internals)]
129 #![feature(trusted_len)]
130 #![feature(try_reserve)]
131 #![feature(unboxed_closures)]
132 #![feature(unicode_internals)]
133 #![feature(unsafe_block_in_unsafe_fn)]
135 #![feature(unsized_locals)]
136 #![feature(allocator_internals)]
137 #![feature(slice_partition_dedup)]
138 #![feature(maybe_uninit_extra, maybe_uninit_slice, maybe_uninit_uninit_array)]
139 #![feature(alloc_layout_extra)]
140 #![feature(trusted_random_access)]
141 #![feature(try_trait)]
142 #![feature(type_alias_impl_trait)]
143 #![feature(associated_type_bounds)]
144 // Allow testing this library
152 // Module with internal macros used by other modules (needs to be included before other modules).
156 // Heaps provided for low-level allocation strategies
160 // Primitive types using the heaps above
162 // Need to conditionally define the mod from `boxed.rs` to avoid
163 // duplicating the lang-items when building in test cfg; but also need
164 // to allow code to have `use boxed::Box;` declarations.
169 pub use std::boxed::Box;
180 #[cfg(target_has_atomic = "ptr")]
182 #[cfg(target_has_atomic = "ptr")]
190 pub use core::ops; // RangeFull
194 #[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
196 pub use core::format_args;