src/liballoc/lib.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! # The Rust core allocation library
  12 //!
  13 //! This is the lowest level library through which allocation in Rust can be
  14 //! performed.
  15 //!
  16 //! This library, like libcore, is not intended for general usage, but rather as
  17 //! a building block of other libraries. The types and interfaces in this
  18 //! library are reexported through the [standard library](../std/index.html),
  19 //! and should not be used through this library.
  20 //!
  21 //! Currently, there are four major definitions in this library.
  22 //!
  23 //! ## Boxed values
  24 //!
  25 //! The [`Box`](boxed/index.html) type is the core owned pointer type in Rust.
  26 //! There can only be one owner of a `Box`, and the owner can decide to mutate
  27 //! the contents, which live on the heap.
  28 //!
  29 //! This type can be sent among tasks efficiently as the size of a `Box` value
  30 //! is the same as that of a pointer. Tree-like data structures are often built
  31 //! with boxes because each node often has only one owner, the parent.
  32 //!
  33 //! ## Reference counted pointers
  34 //!
  35 //! The [`Rc`](rc/index.html) type is a non-threadsafe reference-counted pointer
  36 //! type intended for sharing memory within a task. An `Rc` pointer wraps a
  37 //! type, `T`, and only allows access to `&T`, a shared reference.
  38 //!
  39 //! This type is useful when inherited mutability (such as using `Box`) is too
  40 //! constraining for an application, and is often paired with the `Cell` or
  41 //! `RefCell` types in order to allow mutation.
  42 //!
  43 //! ## Atomically reference counted pointers
  44 //!
  45 //! The [`Arc`](arc/index.html) type is the threadsafe equivalent of the `Rc`
  46 //! type. It provides all the same functionality of `Rc`, except it requires
  47 //! that the contained type `T` is shareable. Additionally, `Arc<T>` is itself
  48 //! sendable while `Rc<T>` is not.
  49 //!
  50 //! This types allows for shared access to the contained data, and is often
  51 //! paired with synchronization primitives such as mutexes to allow mutation of
  52 //! shared resources.
  53 //!
  54 //! ## Heap interfaces
  55 //!
  56 //! The [`heap`](heap/index.html) module defines the low-level interface to the
  57 //! default global allocator. It is not compatible with the libc allocator API.
  58
  59 #![crate_name = "alloc"]
  60 #![unstable(feature = "alloc")]
  61 #![feature(staged_api)]
  62 #![staged_api]
  63 #![crate_type = "rlib"]
  64 #![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  65        html_favicon_url = "http://www.rust-lang.org/favicon.ico",
  66        html_root_url = "http://doc.rust-lang.org/nightly/")]
  67
  68 #![feature(no_std)]
  69 #![no_std]
  70 #![feature(lang_items, unsafe_destructor)]
  71 #![feature(box_syntax)]
  72 #![feature(optin_builtin_traits)]
  73 #![feature(unboxed_closures)]
  74 #![feature(unsafe_no_drop_flag)]
  75 #![feature(core)]
  76 #![cfg_attr(all(not(feature = "external_funcs"), not(feature = "external_crate")),
  77             feature(libc))]
  78
  79
  80 #[macro_use]
  81 extern crate core;
  82
  83 #[cfg(all(not(feature = "external_funcs"), not(feature = "external_crate")))]
  84 extern crate libc;
  85
  86 // Allow testing this library
  87
  88 #[cfg(test)] #[macro_use] extern crate std;
  89 #[cfg(test)] #[macro_use] extern crate log;
  90
  91 // Heaps provided for low-level allocation strategies
  92
  93 pub mod heap;
  94
  95 // Primitive types using the heaps above
  96
  97 #[cfg(not(test))]
  98 pub mod boxed;
  99 #[cfg(test)]
 100 mod boxed_test;
 101 pub mod arc;
 102 pub mod rc;
 103
 104 /// Common out-of-memory routine
 105 #[cold]
 106 #[inline(never)]
 107 pub fn oom() -> ! {
 108     // FIXME(#14674): This really needs to do something other than just abort
 109     //                here, but any printing done must be *guaranteed* to not
 110     //                allocate.
 111     unsafe { core::intrinsics::abort() }
 112 }
 113
 114 // FIXME(#14344): When linking liballoc with libstd, this library will be linked
 115 //                as an rlib (it only exists as an rlib). It turns out that an
 116 //                optimized standard library doesn't actually use *any* symbols
 117 //                from this library. Everything is inlined and optimized away.
 118 //                This means that linkers will actually omit the object for this
 119 //                file, even though it may be needed in the future.
 120 //
 121 //                To get around this for now, we define a dummy symbol which
 122 //                will never get inlined so the stdlib can call it. The stdlib's
 123 //                reference to this symbol will cause this library's object file
 124 //                to get linked in to libstd successfully (the linker won't
 125 //                optimize it out).
 126 #[doc(hidden)]
 127 pub fn fixme_14344_be_sure_to_link_to_collections() {}