<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source to the Rust file `liballoc/rc.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>rc.rs.html -- source</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc source"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../alloc/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="comment">// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="attribute">#![<span class="ident">allow</span>(<span class="ident">deprecated</span>)]</span>
<span class="doccomment">//! Single-threaded reference-counting pointers. 'Rc' stands for 'Reference</span>
<span class="doccomment">//! Counted'.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The type [`Rc<T>`][`Rc`] provides shared ownership of a value of type `T`,</span>
<span class="doccomment">//! allocated in the heap. Invoking [`clone`][clone] on [`Rc`] produces a new</span>
<span class="doccomment">//! pointer to the same value in the heap. When the last [`Rc`] pointer to a</span>
<span class="doccomment">//! given value is destroyed, the pointed-to value is also destroyed.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Shared references in Rust disallow mutation by default, and [`Rc`]</span>
<span class="doccomment">//! is no exception: you cannot generally obtain a mutable reference to</span>
<span class="doccomment">//! something inside an [`Rc`]. If you need mutability, put a [`Cell`]</span>
<span class="doccomment">//! or [`RefCell`] inside the [`Rc`]; see [an example of mutability</span>
<span class="doccomment">//! inside an Rc][mutability].</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`Rc`] uses non-atomic reference counting. This means that overhead is very</span>
<span class="doccomment">//! low, but an [`Rc`] cannot be sent between threads, and consequently [`Rc`]</span>
<span class="doccomment">//! does not implement [`Send`][send]. As a result, the Rust compiler</span>
<span class="doccomment">//! will check *at compile time* that you are not sending [`Rc`]s between</span>
<span class="doccomment">//! threads. If you need multi-threaded, atomic reference counting, use</span>
<span class="doccomment">//! [`sync::Arc`][arc].</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The [`downgrade`][downgrade] method can be used to create a non-owning</span>
<span class="doccomment">//! [`Weak`] pointer. A [`Weak`] pointer can be [`upgrade`][upgrade]d</span>
<span class="doccomment">//! to an [`Rc`], but this will return [`None`] if the value has</span>
<span class="doccomment">//! already been dropped.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! A cycle between [`Rc`] pointers will never be deallocated. For this reason,</span>
<span class="doccomment">//! [`Weak`] is used to break cycles. For example, a tree could have strong</span>
<span class="doccomment">//! [`Rc`] pointers from parent nodes to children, and [`Weak`] pointers from</span>
<span class="doccomment">//! children back to their parents.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! `Rc<T>` automatically dereferences to `T` (via the [`Deref`] trait),</span>
<span class="doccomment">//! so you can call `T`'s methods on a value of type [`Rc<T>`][`Rc`]. To avoid name</span>
<span class="doccomment">//! clashes with `T`'s methods, the methods of [`Rc<T>`][`Rc`] itself are [associated</span>
<span class="doccomment">//! functions][assoc], called using function-like syntax:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! use std::rc::Rc;</span>
<span class="doccomment">//! let my_rc = Rc::new(());</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Rc::downgrade(&my_rc);</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`Weak<T>`][`Weak`] does not auto-dereference to `T`, because the value may have</span>
<span class="doccomment">//! already been destroyed.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Cloning references</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Creating a new reference from an existing reference counted pointer is done using the</span>
<span class="doccomment">//! `Clone` trait implemented for [`Rc<T>`][`Rc`] and [`Weak<T>`][`Weak`].</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! use std::rc::Rc;</span>
<span class="doccomment">//! let foo = Rc::new(vec![1.0, 2.0, 3.0]);</span>
<span class="doccomment">//! // The two syntaxes below are equivalent.</span>
<span class="doccomment">//! let a = foo.clone();</span>
<span class="doccomment">//! let b = Rc::clone(&foo);</span>
<span class="doccomment">//! // a and b both point to the same memory location as foo.</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! The `Rc::clone(&from)` syntax is the most idiomatic because it conveys more explicitly</span>
<span class="doccomment">//! the meaning of the code. In the example above, this syntax makes it easier to see that</span>
<span class="doccomment">//! this code is creating a new reference rather than copying the whole content of foo.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Examples</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Consider a scenario where a set of `Gadget`s are owned by a given `Owner`.</span>
<span class="doccomment">//! We want to have our `Gadget`s point to their `Owner`. We can't do this with</span>
<span class="doccomment">//! unique ownership, because more than one gadget may belong to the same</span>
<span class="doccomment">//! `Owner`. [`Rc`] allows us to share an `Owner` between multiple `Gadget`s,</span>
<span class="doccomment">//! and have the `Owner` remain allocated as long as any `Gadget` points at it.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! use std::rc::Rc;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! struct Owner {</span>
<span class="doccomment">//! name: String,</span>
<span class="doccomment">//! // ...other fields</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! struct Gadget {</span>
<span class="doccomment">//! id: i32,</span>
<span class="doccomment">//! owner: Rc<Owner>,</span>
<span class="doccomment">//! // ...other fields</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! fn main() {</span>
<span class="doccomment">//! // Create a reference-counted `Owner`.</span>
<span class="doccomment">//! let gadget_owner: Rc<Owner> = Rc::new(</span>
<span class="doccomment">//! Owner {</span>
<span class="doccomment">//! name: "Gadget Man".to_string(),</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! );</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Create `Gadget`s belonging to `gadget_owner`. Cloning the `Rc<Owner>`</span>
<span class="doccomment">//! // value gives us a new pointer to the same `Owner` value, incrementing</span>
<span class="doccomment">//! // the reference count in the process.</span>
<span class="doccomment">//! let gadget1 = Gadget {</span>
<span class="doccomment">//! id: 1,</span>
<span class="doccomment">//! owner: Rc::clone(&gadget_owner),</span>
<span class="doccomment">//! };</span>
<span class="doccomment">//! let gadget2 = Gadget {</span>
<span class="doccomment">//! id: 2,</span>
<span class="doccomment">//! owner: Rc::clone(&gadget_owner),</span>
<span class="doccomment">//! };</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Dispose of our local variable `gadget_owner`.</span>
<span class="doccomment">//! drop(gadget_owner);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Despite dropping `gadget_owner`, we're still able to print out the name</span>
<span class="doccomment">//! // of the `Owner` of the `Gadget`s. This is because we've only dropped a</span>
<span class="doccomment">//! // single `Rc<Owner>`, not the `Owner` it points to. As long as there are</span>
<span class="doccomment">//! // other `Rc<Owner>` values pointing at the same `Owner`, it will remain</span>
<span class="doccomment">//! // allocated. The field projection `gadget1.owner.name` works because</span>
<span class="doccomment">//! // `Rc<Owner>` automatically dereferences to `Owner`.</span>
<span class="doccomment">//! println!("Gadget {} owned by {}", gadget1.id, gadget1.owner.name);</span>
<span class="doccomment">//! println!("Gadget {} owned by {}", gadget2.id, gadget2.owner.name);</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // At the end of the function, `gadget1` and `gadget2` are destroyed, and</span>
<span class="doccomment">//! // with them the last counted references to our `Owner`. Gadget Man now</span>
<span class="doccomment">//! // gets destroyed as well.</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! If our requirements change, and we also need to be able to traverse from</span>
<span class="doccomment">//! `Owner` to `Gadget`, we will run into problems. An [`Rc`] pointer from `Owner`</span>
<span class="doccomment">//! to `Gadget` introduces a cycle between the values. This means that their</span>
<span class="doccomment">//! reference counts can never reach 0, and the values will remain allocated</span>
<span class="doccomment">//! forever: a memory leak. In order to get around this, we can use [`Weak`]</span>
<span class="doccomment">//! pointers.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Rust actually makes it somewhat difficult to produce this loop in the first</span>
<span class="doccomment">//! place. In order to end up with two values that point at each other, one of</span>
<span class="doccomment">//! them needs to be mutable. This is difficult because [`Rc`] enforces</span>
<span class="doccomment">//! memory safety by only giving out shared references to the value it wraps,</span>
<span class="doccomment">//! and these don't allow direct mutation. We need to wrap the part of the</span>
<span class="doccomment">//! value we wish to mutate in a [`RefCell`], which provides *interior</span>
<span class="doccomment">//! mutability*: a method to achieve mutability through a shared reference.</span>
<span class="doccomment">//! [`RefCell`] enforces Rust's borrowing rules at runtime.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! use std::rc::Rc;</span>
<span class="doccomment">//! use std::rc::Weak;</span>
<span class="doccomment">//! use std::cell::RefCell;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! struct Owner {</span>
<span class="doccomment">//! name: String,</span>
<span class="doccomment">//! gadgets: RefCell<Vec<Weak<Gadget>>>,</span>
<span class="doccomment">//! // ...other fields</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! struct Gadget {</span>
<span class="doccomment">//! id: i32,</span>
<span class="doccomment">//! owner: Rc<Owner>,</span>
<span class="doccomment">//! // ...other fields</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! fn main() {</span>
<span class="doccomment">//! // Create a reference-counted `Owner`. Note that we've put the `Owner`'s</span>
<span class="doccomment">//! // vector of `Gadget`s inside a `RefCell` so that we can mutate it through</span>
<span class="doccomment">//! // a shared reference.</span>
<span class="doccomment">//! let gadget_owner: Rc<Owner> = Rc::new(</span>
<span class="doccomment">//! Owner {</span>
<span class="doccomment">//! name: "Gadget Man".to_string(),</span>
<span class="doccomment">//! gadgets: RefCell::new(vec![]),</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! );</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Create `Gadget`s belonging to `gadget_owner`, as before.</span>
<span class="doccomment">//! let gadget1 = Rc::new(</span>
<span class="doccomment">//! Gadget {</span>
<span class="doccomment">//! id: 1,</span>
<span class="doccomment">//! owner: Rc::clone(&gadget_owner),</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! );</span>
<span class="doccomment">//! let gadget2 = Rc::new(</span>
<span class="doccomment">//! Gadget {</span>
<span class="doccomment">//! id: 2,</span>
<span class="doccomment">//! owner: Rc::clone(&gadget_owner),</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! );</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Add the `Gadget`s to their `Owner`.</span>
<span class="doccomment">//! {</span>
<span class="doccomment">//! let mut gadgets = gadget_owner.gadgets.borrow_mut();</span>
<span class="doccomment">//! gadgets.push(Rc::downgrade(&gadget1));</span>
<span class="doccomment">//! gadgets.push(Rc::downgrade(&gadget2));</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // `RefCell` dynamic borrow ends here.</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // Iterate over our `Gadget`s, printing their details out.</span>
<span class="doccomment">//! for gadget_weak in gadget_owner.gadgets.borrow().iter() {</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // `gadget_weak` is a `Weak<Gadget>`. Since `Weak` pointers can't</span>
<span class="doccomment">//! // guarantee the value is still allocated, we need to call</span>
<span class="doccomment">//! // `upgrade`, which returns an `Option<Rc<Gadget>>`.</span>
<span class="doccomment">//! //</span>
<span class="doccomment">//! // In this case we know the value still exists, so we simply</span>
<span class="doccomment">//! // `unwrap` the `Option`. In a more complicated program, you might</span>
<span class="doccomment">//! // need graceful error handling for a `None` result.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let gadget = gadget_weak.upgrade().unwrap();</span>
<span class="doccomment">//! println!("Gadget {} owned by {}", gadget.id, gadget.owner.name);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! // At the end of the function, `gadget_owner`, `gadget1`, and `gadget2`</span>
<span class="doccomment">//! // are destroyed. There are now no strong (`Rc`) pointers to the</span>
<span class="doccomment">//! // gadgets, so they are destroyed. This zeroes the reference count on</span>
<span class="doccomment">//! // Gadget Man, so he gets destroyed as well.</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! [`Rc`]: struct.Rc.html</span>
<span class="doccomment">//! [`Weak`]: struct.Weak.html</span>
<span class="doccomment">//! [clone]: ../../std/clone/trait.Clone.html#tymethod.clone</span>
<span class="doccomment">//! [`Cell`]: ../../std/cell/struct.Cell.html</span>
<span class="doccomment">//! [`RefCell`]: ../../std/cell/struct.RefCell.html</span>
<span class="doccomment">//! [send]: ../../std/marker/trait.Send.html</span>
<span class="doccomment">//! [arc]: ../../std/sync/struct.Arc.html</span>
<span class="doccomment">//! [`Deref`]: ../../std/ops/trait.Deref.html</span>
<span class="doccomment">//! [downgrade]: struct.Rc.html#method.downgrade</span>
<span class="doccomment">//! [upgrade]: struct.Weak.html#method.upgrade</span>
<span class="doccomment">//! [`None`]: ../../std/option/enum.Option.html#variant.None</span>
<span class="doccomment">//! [assoc]: ../../book/first-edition/method-syntax.html#associated-functions</span>
<span class="doccomment">//! [mutability]: ../../std/cell/index.html#introducing-mutability-inside-of-something-immutable</span>
<span class="attribute">#![<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">test</span>))]</span>
<span class="kw">use</span> <span class="ident">boxed</span>::<span class="ident">Box</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">boxed</span>::<span class="ident">Box</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">any</span>::<span class="ident">Any</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">borrow</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">cell</span>::<span class="ident">Cell</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">cmp</span>::<span class="ident">Ordering</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">hash</span>::{<span class="ident">Hash</span>, <span class="ident">Hasher</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">intrinsics</span>::<span class="ident">abort</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">marker</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">marker</span>::{<span class="ident">Unsize</span>, <span class="ident">PhantomData</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">mem</span>::{<span class="self">self</span>, <span class="ident">align_of_val</span>, <span class="ident">forget</span>, <span class="ident">size_of_val</span>, <span class="ident">uninitialized</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">ops</span>::<span class="ident">Deref</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">ops</span>::<span class="ident">CoerceUnsized</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">ptr</span>::{<span class="self">self</span>, <span class="ident">NonNull</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">convert</span>::<span class="ident">From</span>;
<span class="kw">use</span> <span class="ident">alloc</span>::{<span class="ident">Global</span>, <span class="ident">Alloc</span>, <span class="ident">Layout</span>, <span class="ident">Opaque</span>, <span class="ident">box_free</span>, <span class="ident">oom</span>};
<span class="kw">use</span> <span class="ident">string</span>::<span class="ident">String</span>;
<span class="kw">use</span> <span class="ident">vec</span>::<span class="ident">Vec</span>;
<span class="kw">struct</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="ident">strong</span>: <span class="ident">Cell</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="ident">weak</span>: <span class="ident">Cell</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="ident">value</span>: <span class="ident">T</span>,
}
<span class="doccomment">/// A single-threaded reference-counting pointer. 'Rc' stands for 'Reference</span>
<span class="doccomment">/// Counted'.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See the [module-level documentation](./index.html) for more details.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The inherent methods of `Rc` are all associated functions, which means</span>
<span class="doccomment">/// that you have to call them as e.g. [`Rc::get_mut(&mut value)`][get_mut] instead of</span>
<span class="doccomment">/// `value.get_mut()`. This avoids conflicts with methods of the inner</span>
<span class="doccomment">/// type `T`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [get_mut]: #method.get_mut</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="ident">ptr</span>: <span class="ident">NonNull</span><span class="op"><</span><span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
<span class="ident">phantom</span>: <span class="ident">PhantomData</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="op">!</span><span class="ident">marker</span>::<span class="ident">Send</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="op">!</span><span class="ident">marker</span>::<span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"coerce_unsized"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"27732"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Unsize</span><span class="op"><</span><span class="ident">U</span><span class="op">></span>, <span class="ident">U</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">CoerceUnsized</span><span class="op"><</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">U</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Constructs a new `Rc<T>`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">value</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Rc</span> {
<span class="comment">// there is an implicit weak pointer owned by all the strong</span>
<span class="comment">// pointers, which ensures that the weak destructor never frees</span>
<span class="comment">// the allocation while the strong destructor is running, even</span>
<span class="comment">// if the weak pointer is stored inside the strong one.</span>
<span class="ident">ptr</span>: <span class="ident">Box</span>::<span class="ident">into_raw_non_null</span>(<span class="kw">box</span> <span class="ident">RcBox</span> {
<span class="ident">strong</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>),
<span class="ident">weak</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>),
<span class="ident">value</span>,
}),
<span class="ident">phantom</span>: <span class="ident">PhantomData</span>,
}
}
<span class="doccomment">/// Returns the contained value, if the `Rc` has exactly one strong reference.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Otherwise, an [`Err`][result] is returned with the same `Rc` that was</span>
<span class="doccomment">/// passed in.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This will succeed even if there are outstanding weak references.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [result]: ../../std/result/enum.Result.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let x = Rc::new(3);</span>
<span class="doccomment">/// assert_eq!(Rc::try_unwrap(x), Ok(3));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let x = Rc::new(4);</span>
<span class="doccomment">/// let _y = Rc::clone(&x);</span>
<span class="doccomment">/// assert_eq!(*Rc::try_unwrap(x).unwrap_err(), 4);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_unique"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">try_unwrap</span>(<span class="ident">this</span>: <span class="self">Self</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, <span class="self">Self</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">this</span>) <span class="op">==</span> <span class="number">1</span> {
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">val</span> <span class="op">=</span> <span class="ident">ptr</span>::<span class="ident">read</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">this</span>); <span class="comment">// copy the contained object</span>
<span class="comment">// Indicate to Weaks that they can't be promoted by decrementing</span>
<span class="comment">// the strong count, and then remove the implicit "strong weak"</span>
<span class="comment">// pointer while also handling drop logic by just crafting a</span>
<span class="comment">// fake Weak.</span>
<span class="ident">this</span>.<span class="ident">dec_strong</span>();
<span class="kw">let</span> <span class="ident">_weak</span> <span class="op">=</span> <span class="ident">Weak</span> { <span class="ident">ptr</span>: <span class="ident">this</span>.<span class="ident">ptr</span> };
<span class="ident">forget</span>(<span class="ident">this</span>);
<span class="prelude-val">Ok</span>(<span class="ident">val</span>)
}
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="ident">this</span>)
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Consumes the `Rc`, returning the wrapped pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// To avoid a memory leak the pointer must be converted back to an `Rc` using</span>
<span class="doccomment">/// [`Rc::from_raw`][from_raw].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [from_raw]: struct.Rc.html#method.from_raw</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let x = Rc::new(10);</span>
<span class="doccomment">/// let x_ptr = Rc::into_raw(x);</span>
<span class="doccomment">/// assert_eq!(unsafe { *x_ptr }, 10);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_raw"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.17.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_raw</span>(<span class="ident">this</span>: <span class="self">Self</span>) <span class="op">-></span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span> {
<span class="kw">let</span> <span class="ident">ptr</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">this</span>;
<span class="ident">mem</span>::<span class="ident">forget</span>(<span class="ident">this</span>);
<span class="ident">ptr</span>
}
<span class="doccomment">/// Constructs an `Rc` from a raw pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The raw pointer must have been previously returned by a call to a</span>
<span class="doccomment">/// [`Rc::into_raw`][into_raw].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function is unsafe because improper use may lead to memory problems. For example, a</span>
<span class="doccomment">/// double-free may occur if the function is called twice on the same raw pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [into_raw]: struct.Rc.html#method.into_raw</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let x = Rc::new(10);</span>
<span class="doccomment">/// let x_ptr = Rc::into_raw(x);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// unsafe {</span>
<span class="doccomment">/// // Convert back to an `Rc` to prevent leak.</span>
<span class="doccomment">/// let x = Rc::from_raw(x_ptr);</span>
<span class="doccomment">/// assert_eq!(*x, 10);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Further calls to `Rc::from_raw(x_ptr)` would be memory unsafe.</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // The memory was freed when `x` went out of scope above, so `x_ptr` is now dangling!</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_raw"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.17.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">from_raw</span>(<span class="ident">ptr</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="comment">// Align the unsized value to the end of the RcBox.</span>
<span class="comment">// Because it is ?Sized, it will always be the last field in memory.</span>
<span class="kw">let</span> <span class="ident">align</span> <span class="op">=</span> <span class="ident">align_of_val</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">ptr</span>);
<span class="kw">let</span> <span class="ident">layout</span> <span class="op">=</span> <span class="ident">Layout</span>::<span class="ident">new</span>::<span class="op"><</span><span class="ident">RcBox</span><span class="op"><</span>()<span class="op">>></span>();
<span class="kw">let</span> <span class="ident">offset</span> <span class="op">=</span> (<span class="ident">layout</span>.<span class="ident">size</span>() <span class="op">+</span> <span class="ident">layout</span>.<span class="ident">padding_needed_for</span>(<span class="ident">align</span>)) <span class="kw">as</span> <span class="ident">isize</span>;
<span class="comment">// Reverse the offset to find the original RcBox.</span>
<span class="kw">let</span> <span class="ident">fake_ptr</span> <span class="op">=</span> <span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">let</span> <span class="ident">rc_ptr</span> <span class="op">=</span> <span class="ident">set_data_ptr</span>(<span class="ident">fake_ptr</span>, (<span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>).<span class="ident">offset</span>(<span class="op">-</span><span class="ident">offset</span>));
<span class="ident">Rc</span> {
<span class="ident">ptr</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">rc_ptr</span>),
<span class="ident">phantom</span>: <span class="ident">PhantomData</span>,
}
}
<span class="doccomment">/// Creates a new [`Weak`][weak] pointer to this value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let weak_five = Rc::downgrade(&five);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">downgrade</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">this</span>.<span class="ident">inc_weak</span>();
<span class="ident">Weak</span> { <span class="ident">ptr</span>: <span class="ident">this</span>.<span class="ident">ptr</span> }
}
<span class="doccomment">/// Gets the number of [`Weak`][weak] pointers to this value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">/// let _weak_five = Rc::downgrade(&five);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(1, Rc::weak_count(&five));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_counts"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.15.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">weak_count</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="ident">this</span>.<span class="ident">weak</span>() <span class="op">-</span> <span class="number">1</span>
}
<span class="doccomment">/// Gets the number of strong (`Rc`) pointers to this value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">/// let _also_five = Rc::clone(&five);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(2, Rc::strong_count(&five));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_counts"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.15.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">strong_count</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="ident">this</span>.<span class="ident">strong</span>()
}
<span class="doccomment">/// Returns true if there are no other `Rc` or [`Weak`][weak] pointers to</span>
<span class="doccomment">/// this inner value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">is_unique</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="ident">this</span>) <span class="op">==</span> <span class="number">0</span> <span class="op">&&</span> <span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="ident">this</span>) <span class="op">==</span> <span class="number">1</span>
}
<span class="doccomment">/// Returns a mutable reference to the inner value, if there are</span>
<span class="doccomment">/// no other `Rc` or [`Weak`][weak] pointers to the same value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns [`None`] otherwise, because it is not safe to</span>
<span class="doccomment">/// mutate a shared value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See also [`make_mut`][make_mut], which will [`clone`][clone]</span>
<span class="doccomment">/// the inner value when it's shared.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="doccomment">/// [`None`]: ../../std/option/enum.Option.html#variant.None</span>
<span class="doccomment">/// [make_mut]: struct.Rc.html#method.make_mut</span>
<span class="doccomment">/// [clone]: ../../std/clone/trait.Clone.html#tymethod.clone</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut x = Rc::new(3);</span>
<span class="doccomment">/// *Rc::get_mut(&mut x).unwrap() = 4;</span>
<span class="doccomment">/// assert_eq!(*x, 4);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let _y = Rc::clone(&x);</span>
<span class="doccomment">/// assert!(Rc::get_mut(&mut x).is_none());</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_unique"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_mut</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">Self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="ident">this</span>) {
<span class="kw">unsafe</span> {
<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">this</span>.<span class="ident">ptr</span>.<span class="ident">as_mut</span>().<span class="ident">value</span>)
}
} <span class="kw">else</span> {
<span class="prelude-val">None</span>
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"ptr_eq"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.17.0"</span>)]</span>
<span class="doccomment">/// Returns true if the two `Rc`s point to the same value (not</span>
<span class="doccomment">/// just values that compare as equal).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">/// let same_five = Rc::clone(&five);</span>
<span class="doccomment">/// let other_five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(Rc::ptr_eq(&five, &same_five));</span>
<span class="doccomment">/// assert!(!Rc::ptr_eq(&five, &other_five));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">ptr_eq</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="self">Self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">this</span>.<span class="ident">ptr</span>.<span class="ident">as_ptr</span>() <span class="op">==</span> <span class="ident">other</span>.<span class="ident">ptr</span>.<span class="ident">as_ptr</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Clone</span><span class="op">></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Makes a mutable reference into the given `Rc`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If there are other `Rc` or [`Weak`][weak] pointers to the same value,</span>
<span class="doccomment">/// then `make_mut` will invoke [`clone`][clone] on the inner value to</span>
<span class="doccomment">/// ensure unique ownership. This is also referred to as clone-on-write.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// See also [`get_mut`][get_mut], which will fail rather than cloning.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="doccomment">/// [clone]: ../../std/clone/trait.Clone.html#tymethod.clone</span>
<span class="doccomment">/// [get_mut]: struct.Rc.html#method.get_mut</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut data = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// *Rc::make_mut(&mut data) += 1; // Won't clone anything</span>
<span class="doccomment">/// let mut other_data = Rc::clone(&data); // Won't clone inner data</span>
<span class="doccomment">/// *Rc::make_mut(&mut data) += 1; // Clones inner data</span>
<span class="doccomment">/// *Rc::make_mut(&mut data) += 1; // Won't clone anything</span>
<span class="doccomment">/// *Rc::make_mut(&mut other_data) *= 2; // Won't clone anything</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Now `data` and `other_data` point to different values.</span>
<span class="doccomment">/// assert_eq!(*data, 8);</span>
<span class="doccomment">/// assert_eq!(*other_data, 12);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_unique"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">make_mut</span>(<span class="ident">this</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">Self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span> {
<span class="kw">if</span> <span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="ident">this</span>) <span class="op">!=</span> <span class="number">1</span> {
<span class="comment">// Gotta clone the data, there are other Rcs</span>
<span class="kw-2">*</span><span class="ident">this</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>((<span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">this</span>).<span class="ident">clone</span>())
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="ident">this</span>) <span class="op">!=</span> <span class="number">0</span> {
<span class="comment">// Can just steal the data, all that's left is Weaks</span>
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">swap</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">ptr</span>::<span class="ident">read</span>(<span class="kw-2">&</span><span class="ident">this</span>.<span class="ident">ptr</span>.<span class="ident">as_ref</span>().<span class="ident">value</span>));
<span class="ident">mem</span>::<span class="ident">swap</span>(<span class="ident">this</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">swap</span>);
<span class="ident">swap</span>.<span class="ident">dec_strong</span>();
<span class="comment">// Remove implicit strong-weak ref (no need to craft a fake</span>
<span class="comment">// Weak here -- we know other Weaks can clean up for us)</span>
<span class="ident">swap</span>.<span class="ident">dec_weak</span>();
<span class="ident">forget</span>(<span class="ident">swap</span>);
}
}
<span class="comment">// This unsafety is ok because we're guaranteed that the pointer</span>
<span class="comment">// returned is the *only* pointer that will ever be returned to T. Our</span>
<span class="comment">// reference count is guaranteed to be 1 at this point, and we required</span>
<span class="comment">// the `Rc<T>` itself to be `mut`, so we're returning the only possible</span>
<span class="comment">// reference to the inner value.</span>
<span class="kw">unsafe</span> {
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">this</span>.<span class="ident">ptr</span>.<span class="ident">as_mut</span>().<span class="ident">value</span>
}
}
}
<span class="kw">impl</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">Any</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_downcast"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"44608"</span>)]</span>
<span class="doccomment">/// Attempt to downcast the `Rc<Any>` to a concrete type.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// #![feature(rc_downcast)]</span>
<span class="doccomment">/// use std::any::Any;</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn print_if_string(value: Rc<Any>) {</span>
<span class="doccomment">/// if let Ok(string) = value.downcast::<String>() {</span>
<span class="doccomment">/// println!("String ({}): {}", string.len(), string);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn main() {</span>
<span class="doccomment">/// let my_string = "Hello World".to_string();</span>
<span class="doccomment">/// print_if_string(Rc::new(my_string));</span>
<span class="doccomment">/// print_if_string(Rc::new(0i8));</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">downcast</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Any</span><span class="op">></span>(<span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Rc</span><span class="op"><</span><span class="ident">Any</span><span class="op">>></span> {
<span class="kw">if</span> (<span class="kw-2">*</span><span class="self">self</span>).<span class="ident">is</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span>() {
<span class="comment">// avoid the pointer arithmetic in from_raw</span>
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">raw</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">Any</span><span class="op">></span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_ptr</span>();
<span class="ident">forget</span>(<span class="self">self</span>);
<span class="prelude-val">Ok</span>(<span class="ident">Rc</span> {
<span class="ident">ptr</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">raw</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw">_</span>),
<span class="ident">phantom</span>: <span class="ident">PhantomData</span>,
})
}
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="self">self</span>)
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// Allocates an `RcBox<T>` with sufficient space for an unsized value</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">allocate_for_ptr</span>(<span class="ident">ptr</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span>) <span class="op">-></span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="comment">// Create a fake RcBox to find allocation size and alignment</span>
<span class="kw">let</span> <span class="ident">fake_ptr</span> <span class="op">=</span> <span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">let</span> <span class="ident">layout</span> <span class="op">=</span> <span class="ident">Layout</span>::<span class="ident">for_value</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">fake_ptr</span>);
<span class="kw">let</span> <span class="ident">mem</span> <span class="op">=</span> <span class="ident">Global</span>.<span class="ident">alloc</span>(<span class="ident">layout</span>)
.<span class="ident">unwrap_or_else</span>(<span class="op">|</span><span class="kw">_</span><span class="op">|</span> <span class="ident">oom</span>());
<span class="comment">// Initialize the real RcBox</span>
<span class="kw">let</span> <span class="ident">inner</span> <span class="op">=</span> <span class="ident">set_data_ptr</span>(<span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span>, <span class="ident">mem</span>.<span class="ident">as_ptr</span>() <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>) <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="ident">ptr</span>::<span class="ident">write</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> (<span class="kw-2">*</span><span class="ident">inner</span>).<span class="ident">strong</span>, <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>));
<span class="ident">ptr</span>::<span class="ident">write</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> (<span class="kw-2">*</span><span class="ident">inner</span>).<span class="ident">weak</span>, <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>));
<span class="ident">inner</span>
}
<span class="kw">fn</span> <span class="ident">from_box</span>(<span class="ident">v</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">box_unique</span> <span class="op">=</span> <span class="ident">Box</span>::<span class="ident">into_unique</span>(<span class="ident">v</span>);
<span class="kw">let</span> <span class="ident">bptr</span> <span class="op">=</span> <span class="ident">box_unique</span>.<span class="ident">as_ptr</span>();
<span class="kw">let</span> <span class="ident">value_size</span> <span class="op">=</span> <span class="ident">size_of_val</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">bptr</span>);
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="self">Self</span>::<span class="ident">allocate_for_ptr</span>(<span class="ident">bptr</span>);
<span class="comment">// Copy value as bytes</span>
<span class="ident">ptr</span>::<span class="ident">copy_nonoverlapping</span>(
<span class="ident">bptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">u8</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> (<span class="kw-2">*</span><span class="ident">ptr</span>).<span class="ident">value</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw">_</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>,
<span class="ident">value_size</span>);
<span class="comment">// Free the allocation without dropping its contents</span>
<span class="ident">box_free</span>(<span class="ident">box_unique</span>);
<span class="ident">Rc</span> { <span class="ident">ptr</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">ptr</span>), <span class="ident">phantom</span>: <span class="ident">PhantomData</span> }
}
}
}
<span class="comment">// Sets the data pointer of a `?Sized` raw pointer.</span>
<span class="comment">//</span>
<span class="comment">// For a slice/trait object, this sets the `data` field and leaves the rest</span>
<span class="comment">// unchanged. For a sized raw pointer, this simply sets the pointer.</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">set_data_ptr</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span>, <span class="ident">U</span><span class="op">></span>(<span class="kw-2">mut</span> <span class="ident">ptr</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span>, <span class="ident">data</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">U</span>) <span class="op">-></span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span> {
<span class="ident">ptr</span>::<span class="ident">write</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw">_</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>, <span class="ident">data</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">u8</span>);
<span class="ident">ptr</span>
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="comment">// Copy elements from slice into newly allocated Rc<[T]></span>
<span class="comment">//</span>
<span class="comment">// Unsafe because the caller must either take ownership or bind `T: Copy`</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">copy_from_slice</span>(<span class="ident">v</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="kw">let</span> <span class="ident">v_ptr</span> <span class="op">=</span> <span class="ident">v</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> [<span class="ident">T</span>];
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="self">Self</span>::<span class="ident">allocate_for_ptr</span>(<span class="ident">v_ptr</span>);
<span class="ident">ptr</span>::<span class="ident">copy_nonoverlapping</span>(
<span class="ident">v</span>.<span class="ident">as_ptr</span>(),
<span class="kw-2">&</span><span class="kw-2">mut</span> (<span class="kw-2">*</span><span class="ident">ptr</span>).<span class="ident">value</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> [<span class="ident">T</span>] <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span>,
<span class="ident">v</span>.<span class="ident">len</span>());
<span class="ident">Rc</span> { <span class="ident">ptr</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">ptr</span>), <span class="ident">phantom</span>: <span class="ident">PhantomData</span> }
}
}
<span class="kw">trait</span> <span class="ident">RcFromSlice</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">from_slice</span>(<span class="ident">slice</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) <span class="op">-></span> <span class="self">Self</span>;
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Clone</span><span class="op">></span> <span class="ident">RcFromSlice</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="ident">default</span> <span class="kw">fn</span> <span class="ident">from_slice</span>(<span class="ident">v</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) <span class="op">-></span> <span class="self">Self</span> {
<span class="comment">// Panic guard while cloning T elements.</span>
<span class="comment">// In the event of a panic, elements that have been written</span>
<span class="comment">// into the new RcBox will be dropped, then the memory freed.</span>
<span class="kw">struct</span> <span class="ident">Guard</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">mem</span>: <span class="ident">NonNull</span><span class="op"><</span><span class="ident">Opaque</span><span class="op">></span>,
<span class="ident">elems</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span>,
<span class="ident">layout</span>: <span class="ident">Layout</span>,
<span class="ident">n_elems</span>: <span class="ident">usize</span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Guard</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">slice</span>::<span class="ident">from_raw_parts_mut</span>;
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">from_raw_parts_mut</span>(<span class="self">self</span>.<span class="ident">elems</span>, <span class="self">self</span>.<span class="ident">n_elems</span>);
<span class="ident">ptr</span>::<span class="ident">drop_in_place</span>(<span class="ident">slice</span>);
<span class="ident">Global</span>.<span class="ident">dealloc</span>(<span class="self">self</span>.<span class="ident">mem</span>, <span class="self">self</span>.<span class="ident">layout</span>.<span class="ident">clone</span>());
}
}
}
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">v_ptr</span> <span class="op">=</span> <span class="ident">v</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> [<span class="ident">T</span>];
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="self">Self</span>::<span class="ident">allocate_for_ptr</span>(<span class="ident">v_ptr</span>);
<span class="kw">let</span> <span class="ident">mem</span> <span class="op">=</span> <span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw">_</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Opaque</span>;
<span class="kw">let</span> <span class="ident">layout</span> <span class="op">=</span> <span class="ident">Layout</span>::<span class="ident">for_value</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">ptr</span>);
<span class="comment">// Pointer to first element</span>
<span class="kw">let</span> <span class="ident">elems</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> (<span class="kw-2">*</span><span class="ident">ptr</span>).<span class="ident">value</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> [<span class="ident">T</span>] <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">T</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">guard</span> <span class="op">=</span> <span class="ident">Guard</span>{
<span class="ident">mem</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">mem</span>),
<span class="ident">elems</span>: <span class="ident">elems</span>,
<span class="ident">layout</span>: <span class="ident">layout</span>,
<span class="ident">n_elems</span>: <span class="number">0</span>,
};
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">item</span>) <span class="kw">in</span> <span class="ident">v</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="ident">ptr</span>::<span class="ident">write</span>(<span class="ident">elems</span>.<span class="ident">offset</span>(<span class="ident">i</span> <span class="kw">as</span> <span class="ident">isize</span>), <span class="ident">item</span>.<span class="ident">clone</span>());
<span class="ident">guard</span>.<span class="ident">n_elems</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="comment">// All clear. Forget the guard so it doesn't free the new RcBox.</span>
<span class="ident">forget</span>(<span class="ident">guard</span>);
<span class="ident">Rc</span> { <span class="ident">ptr</span>: <span class="ident">NonNull</span>::<span class="ident">new_unchecked</span>(<span class="ident">ptr</span>), <span class="ident">phantom</span>: <span class="ident">PhantomData</span> }
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Copy</span><span class="op">></span> <span class="ident">RcFromSlice</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from_slice</span>(<span class="ident">v</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) <span class="op">-></span> <span class="self">Self</span> {
<span class="kw">unsafe</span> { <span class="ident">Rc</span>::<span class="ident">copy_from_slice</span>(<span class="ident">v</span>) }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Deref</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Target</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">deref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">value</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="attribute">#[<span class="ident">may_dangle</span>]</span> <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Drops the `Rc`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This will decrement the strong reference count. If the strong reference</span>
<span class="doccomment">/// count reaches zero then the only other references (if any) are</span>
<span class="doccomment">/// [`Weak`][weak], so we `drop` the inner value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [weak]: struct.Weak.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// struct Foo;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// impl Drop for Foo {</span>
<span class="doccomment">/// fn drop(&mut self) {</span>
<span class="doccomment">/// println!("dropped!");</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let foo = Rc::new(Foo);</span>
<span class="doccomment">/// let foo2 = Rc::clone(&foo);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// drop(foo); // Doesn't print anything</span>
<span class="doccomment">/// drop(foo2); // Prints "dropped!"</span>
<span class="doccomment">/// ```</span>
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">dec_strong</span>();
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">strong</span>() <span class="op">==</span> <span class="number">0</span> {
<span class="comment">// destroy the contained object</span>
<span class="ident">ptr</span>::<span class="ident">drop_in_place</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_mut</span>());
<span class="comment">// remove the implicit "strong weak" pointer now that we've</span>
<span class="comment">// destroyed the contents.</span>
<span class="self">self</span>.<span class="ident">dec_weak</span>();
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">weak</span>() <span class="op">==</span> <span class="number">0</span> {
<span class="ident">Global</span>.<span class="ident">dealloc</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_opaque</span>(), <span class="ident">Layout</span>::<span class="ident">for_value</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_ref</span>()));
}
}
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Makes a clone of the `Rc` pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This creates another pointer to the same inner value, increasing the</span>
<span class="doccomment">/// strong reference count.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Rc::clone(&five);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inc_strong</span>();
<span class="ident">Rc</span> { <span class="ident">ptr</span>: <span class="self">self</span>.<span class="ident">ptr</span>, <span class="ident">phantom</span>: <span class="ident">PhantomData</span> }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Default</span><span class="op">></span> <span class="ident">Default</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates a new `Rc<T>`, with the `Default` value for `T`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let x: Rc<i32> = Default::default();</span>
<span class="doccomment">/// assert_eq!(*x, 0);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">default</span>() <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">Default</span>::<span class="ident">default</span>())
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">PartialEq</span><span class="op">></span> <span class="ident">PartialEq</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Equality for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Two `Rc`s are equal if their inner values are equal.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five == Rc::new(5));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">eq</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op">==</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
<span class="doccomment">/// Inequality for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Two `Rc`s are unequal if their inner values are unequal.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five != Rc::new(6));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">ne</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Eq</span><span class="op">></span> <span class="ident">Eq</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">PartialOrd</span><span class="op">></span> <span class="ident">PartialOrd</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Partial comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `partial_cmp()` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">/// use std::cmp::Ordering;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(Some(Ordering::Less), five.partial_cmp(&Rc::new(6)));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">partial_cmp</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Ordering</span><span class="op">></span> {
(<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>).<span class="ident">partial_cmp</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>)
}
<span class="doccomment">/// Less-than comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `<` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five < Rc::new(6));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">lt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op"><</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
<span class="doccomment">/// 'Less than or equal to' comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `<=` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five <= Rc::new(5));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">le</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op"><=</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
<span class="doccomment">/// Greater-than comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `>` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five > Rc::new(4));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">gt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op">></span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
<span class="doccomment">/// 'Greater than or equal to' comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `>=` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(five >= Rc::new(5));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">ge</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="op">>=</span> <span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Ord</span><span class="op">></span> <span class="ident">Ord</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Comparison for two `Rc`s.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The two are compared by calling `cmp()` on their inner values.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">/// use std::cmp::Ordering;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(Ordering::Less, five.cmp(&Rc::new(6)));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">cmp</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">Ordering</span> {
(<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>).<span class="ident">cmp</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Hash</span><span class="op">></span> <span class="ident">Hash</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">hash</span><span class="op"><</span><span class="ident">H</span>: <span class="ident">Hasher</span><span class="op">></span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">H</span>) {
(<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>).<span class="ident">hash</span>(<span class="ident">state</span>);
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Display</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>::<span class="ident">Display</span>::<span class="ident">fmt</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="ident">f</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>::<span class="ident">Debug</span>::<span class="ident">fmt</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="ident">f</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Pointer</span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>::<span class="ident">Pointer</span>::<span class="ident">fmt</span>(<span class="kw-2">&</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span>), <span class="ident">f</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"from_for_ptrs"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.6.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">t</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">t</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"shared_from_slice"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.21.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="ident">Clone</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> [<span class="ident">T</span>]<span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">v</span>: <span class="kw-2">&</span>[<span class="ident">T</span>]) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="op"><</span><span class="self">Self</span> <span class="kw">as</span> <span class="ident">RcFromSlice</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>::<span class="ident">from_slice</span>(<span class="ident">v</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"shared_from_slice"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.21.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">v</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">rc</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="op"><</span>[<span class="ident">u8</span>]<span class="op">></span>::<span class="ident">from</span>(<span class="ident">v</span>.<span class="ident">as_bytes</span>());
<span class="kw">unsafe</span> { <span class="ident">Rc</span>::<span class="ident">from_raw</span>(<span class="ident">Rc</span>::<span class="ident">into_raw</span>(<span class="ident">rc</span>) <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">str</span>) }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"shared_from_slice"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.21.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">From</span><span class="op"><</span><span class="ident">String</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">v</span>: <span class="ident">String</span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> {
<span class="ident">Rc</span>::<span class="ident">from</span>(<span class="kw-2">&</span><span class="ident">v</span>[..])
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"shared_from_slice"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.21.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">Box</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">v</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Rc</span>::<span class="ident">from_box</span>(<span class="ident">v</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"shared_from_slice"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.21.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="kw-2">mut</span> <span class="ident">v</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">T</span>]<span class="op">></span> {
<span class="kw">unsafe</span> {
<span class="kw">let</span> <span class="ident">rc</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">v</span>);
<span class="comment">// Allow the Vec to free its memory, but not destroy its contents</span>
<span class="ident">v</span>.<span class="ident">set_len</span>(<span class="number">0</span>);
<span class="ident">rc</span>
}
}
}
<span class="doccomment">/// `Weak` is a version of [`Rc`] that holds a non-owning reference to the</span>
<span class="doccomment">/// managed value. The value is accessed by calling [`upgrade`] on the `Weak`</span>
<span class="doccomment">/// pointer, which returns an [`Option`]`<`[`Rc`]`<T>>`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Since a `Weak` reference does not count towards ownership, it will not</span>
<span class="doccomment">/// prevent the inner value from being dropped, and `Weak` itself makes no</span>
<span class="doccomment">/// guarantees about the value still being present and may return [`None`]</span>
<span class="doccomment">/// when [`upgrade`]d.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// A `Weak` pointer is useful for keeping a temporary reference to the value</span>
<span class="doccomment">/// within [`Rc`] without extending its lifetime. It is also used to prevent</span>
<span class="doccomment">/// circular references between [`Rc`] pointers, since mutual owning references</span>
<span class="doccomment">/// would never allow either [`Rc`] to be dropped. For example, a tree could</span>
<span class="doccomment">/// have strong [`Rc`] pointers from parent nodes to children, and `Weak`</span>
<span class="doccomment">/// pointers from children back to their parents.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The typical way to obtain a `Weak` pointer is to call [`Rc::downgrade`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Rc`]: struct.Rc.html</span>
<span class="doccomment">/// [`Rc::downgrade`]: struct.Rc.html#method.downgrade</span>
<span class="doccomment">/// [`upgrade`]: struct.Weak.html#method.upgrade</span>
<span class="doccomment">/// [`Option`]: ../../std/option/enum.Option.html</span>
<span class="doccomment">/// [`None`]: ../../std/option/enum.Option.html#variant.None</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="ident">ptr</span>: <span class="ident">NonNull</span><span class="op"><</span><span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="op">!</span><span class="ident">marker</span>::<span class="ident">Send</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="op">!</span><span class="ident">marker</span>::<span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"coerce_unsized"</span>, <span class="ident">issue</span> <span class="op">=</span> <span class="string">"27732"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Unsize</span><span class="op"><</span><span class="ident">U</span><span class="op">></span>, <span class="ident">U</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">CoerceUnsized</span><span class="op"><</span><span class="ident">Weak</span><span class="op"><</span><span class="ident">U</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Constructs a new `Weak<T>`, allocating memory for `T` without initializing</span>
<span class="doccomment">/// it. Calling [`upgrade`] on the return value always gives [`None`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`upgrade`]: struct.Weak.html#method.upgrade</span>
<span class="doccomment">/// [`None`]: ../../std/option/enum.Option.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Weak;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let empty: Weak<i64> = Weak::new();</span>
<span class="doccomment">/// assert!(empty.upgrade().is_none());</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"downgraded_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.10.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">unsafe</span> {
<span class="ident">Weak</span> {
<span class="ident">ptr</span>: <span class="ident">Box</span>::<span class="ident">into_raw_non_null</span>(<span class="kw">box</span> <span class="ident">RcBox</span> {
<span class="ident">strong</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">0</span>),
<span class="ident">weak</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>),
<span class="ident">value</span>: <span class="ident">uninitialized</span>(),
}),
}
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Attempts to upgrade the `Weak` pointer to an [`Rc`], extending</span>
<span class="doccomment">/// the lifetime of the value if successful.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns [`None`] if the value has since been dropped.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Rc`]: struct.Rc.html</span>
<span class="doccomment">/// [`None`]: ../../std/option/enum.Option.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Rc;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let five = Rc::new(5);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let weak_five = Rc::downgrade(&five);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let strong_five: Option<Rc<_>> = weak_five.upgrade();</span>
<span class="doccomment">/// assert!(strong_five.is_some());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Destroy all strong pointers.</span>
<span class="doccomment">/// drop(strong_five);</span>
<span class="doccomment">/// drop(five);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(weak_five.upgrade().is_none());</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">upgrade</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">strong</span>() <span class="op">==</span> <span class="number">0</span> {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="self">self</span>.<span class="ident">inc_strong</span>();
<span class="prelude-val">Some</span>(<span class="ident">Rc</span> { <span class="ident">ptr</span>: <span class="self">self</span>.<span class="ident">ptr</span>, <span class="ident">phantom</span>: <span class="ident">PhantomData</span> })
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Drops the `Weak` pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::{Rc, Weak};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// struct Foo;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// impl Drop for Foo {</span>
<span class="doccomment">/// fn drop(&mut self) {</span>
<span class="doccomment">/// println!("dropped!");</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let foo = Rc::new(Foo);</span>
<span class="doccomment">/// let weak_foo = Rc::downgrade(&foo);</span>
<span class="doccomment">/// let other_weak_foo = Weak::clone(&weak_foo);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// drop(weak_foo); // Doesn't print anything</span>
<span class="doccomment">/// drop(foo); // Prints "dropped!"</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert!(other_weak_foo.upgrade().is_none());</span>
<span class="doccomment">/// ```</span>
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">dec_weak</span>();
<span class="comment">// the weak count starts at 1, and will only go to zero if all</span>
<span class="comment">// the strong pointers have disappeared.</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">weak</span>() <span class="op">==</span> <span class="number">0</span> {
<span class="ident">Global</span>.<span class="ident">dealloc</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_opaque</span>(), <span class="ident">Layout</span>::<span class="ident">for_value</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_ref</span>()));
}
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Makes a clone of the `Weak` pointer that points to the same value.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::{Rc, Weak};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let weak_five = Rc::downgrade(&Rc::new(5));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Weak::clone(&weak_five);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inc_weak</span>();
<span class="ident">Weak</span> { <span class="ident">ptr</span>: <span class="self">self</span>.<span class="ident">ptr</span> }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rc_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.4.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"(Weak)"</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"downgraded_weak"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.10.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Default</span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Constructs a new `Weak<T>`, allocating memory for `T` without initializing</span>
<span class="doccomment">/// it. Calling [`upgrade`] on the return value always gives [`None`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`upgrade`]: struct.Weak.html#method.upgrade</span>
<span class="doccomment">/// [`None`]: ../../std/option/enum.Option.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::rc::Weak;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let empty: Weak<i64> = Default::default();</span>
<span class="doccomment">/// assert!(empty.upgrade().is_none());</span>
<span class="doccomment">/// ```</span>
<span class="kw">fn</span> <span class="ident">default</span>() <span class="op">-></span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Weak</span>::<span class="ident">new</span>()
}
}
<span class="comment">// NOTE: We checked_add here to deal with mem::forget safety. In particular</span>
<span class="comment">// if you mem::forget Rcs (or Weaks), the ref-count can overflow, and then</span>
<span class="comment">// you can free the allocation while outstanding Rcs (or Weaks) exist.</span>
<span class="comment">// We abort because this is such a degenerate scenario that we don't care about</span>
<span class="comment">// what happens -- no real program should ever experience this.</span>
<span class="comment">//</span>
<span class="comment">// This should have negligible overhead since you don't actually need to</span>
<span class="comment">// clone these much in Rust thanks to ownership and move-semantics.</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">trait</span> <span class="ident">RcBoxPtr</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">inner</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">strong</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">strong</span>.<span class="ident">get</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">inc_strong</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">strong</span>.<span class="ident">set</span>(<span class="self">self</span>.<span class="ident">strong</span>().<span class="ident">checked_add</span>(<span class="number">1</span>).<span class="ident">unwrap_or_else</span>(<span class="op">||</span> <span class="kw">unsafe</span> { <span class="ident">abort</span>() }));
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">dec_strong</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">strong</span>.<span class="ident">set</span>(<span class="self">self</span>.<span class="ident">strong</span>() <span class="op">-</span> <span class="number">1</span>);
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">weak</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">weak</span>.<span class="ident">get</span>()
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">inc_weak</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">weak</span>.<span class="ident">set</span>(<span class="self">self</span>.<span class="ident">weak</span>().<span class="ident">checked_add</span>(<span class="number">1</span>).<span class="ident">unwrap_or_else</span>(<span class="op">||</span> <span class="kw">unsafe</span> { <span class="ident">abort</span>() }));
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">dec_weak</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="self">self</span>.<span class="ident">inner</span>().<span class="ident">weak</span>.<span class="ident">set</span>(<span class="self">self</span>.<span class="ident">weak</span>() <span class="op">-</span> <span class="number">1</span>);
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">RcBoxPtr</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">inner</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_ref</span>()
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">RcBoxPtr</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Weak</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">always</span>)]</span>
<span class="kw">fn</span> <span class="ident">inner</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">RcBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">as_ref</span>()
}
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">tests</span> {
<span class="kw">use</span> <span class="kw">super</span>::{<span class="ident">Rc</span>, <span class="ident">Weak</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">boxed</span>::<span class="ident">Box</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">cell</span>::<span class="ident">RefCell</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">option</span>::<span class="prelude-ty">Option</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">option</span>::<span class="prelude-ty">Option</span>::{<span class="prelude-val">None</span>, <span class="prelude-val">Some</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">result</span>::<span class="prelude-ty">Result</span>::{<span class="prelude-val">Err</span>, <span class="prelude-val">Ok</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">mem</span>::<span class="ident">drop</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">clone</span>::<span class="ident">Clone</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">convert</span>::<span class="ident">From</span>;
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_clone</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">RefCell</span>::<span class="ident">new</span>(<span class="number">5</span>));
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="kw-2">*</span><span class="ident">x</span>.<span class="ident">borrow_mut</span>() <span class="op">=</span> <span class="number">20</span>;
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">y</span>.<span class="ident">borrow</span>(), <span class="number">20</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_simple</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">x</span>, <span class="number">5</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_simple_clone</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">x</span>, <span class="number">5</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">y</span>, <span class="number">5</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_destructor</span>() {
<span class="kw">let</span> <span class="ident">x</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Box</span><span class="op"><</span><span class="kw">_</span><span class="op">>></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="kw">box</span> <span class="number">5</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span>, <span class="number">5</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_live</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">x</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">y</span>.<span class="ident">upgrade</span>().<span class="ident">is_some</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_dead</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">x</span>);
<span class="ident">drop</span>(<span class="ident">x</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">y</span>.<span class="ident">upgrade</span>().<span class="ident">is_none</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">weak_self_cyclic</span>() {
<span class="kw">struct</span> <span class="ident">Cycle</span> {
<span class="ident">x</span>: <span class="ident">RefCell</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Weak</span><span class="op"><</span><span class="ident">Cycle</span><span class="op">>></span><span class="op">></span>,
}
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">Cycle</span> { <span class="ident">x</span>: <span class="ident">RefCell</span>::<span class="ident">new</span>(<span class="prelude-val">None</span>) });
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">a</span>.<span class="ident">clone</span>());
<span class="kw-2">*</span><span class="ident">a</span>.<span class="ident">x</span>.<span class="ident">borrow_mut</span>() <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">b</span>);
<span class="comment">// hopefully we don't double-free (or leak)...</span>
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">is_unique</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">3</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="kw-2">&</span><span class="ident">x</span>));
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="kw-2">&</span><span class="ident">x</span>));
<span class="ident">drop</span>(<span class="ident">y</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="kw-2">&</span><span class="ident">x</span>));
<span class="kw">let</span> <span class="ident">w</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">x</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="kw-2">&</span><span class="ident">x</span>));
<span class="ident">drop</span>(<span class="ident">w</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">is_unique</span>(<span class="kw-2">&</span><span class="ident">x</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_strong_count</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="kw">let</span> <span class="ident">w</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">a</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">w</span>.<span class="ident">upgrade</span>().<span class="ident">expect</span>(<span class="string">"upgrade of live rc failed"</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">b</span>) <span class="op">==</span> <span class="number">2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">2</span>);
<span class="ident">drop</span>(<span class="ident">w</span>);
<span class="ident">drop</span>(<span class="ident">a</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">b</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">b</span>) <span class="op">==</span> <span class="number">2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">c</span>) <span class="op">==</span> <span class="number">2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_weak_count</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">0</span>);
<span class="kw">let</span> <span class="ident">w</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">a</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="ident">drop</span>(<span class="ident">w</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">0</span>);
<span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">a</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">strong_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">weak_count</span>(<span class="kw-2">&</span><span class="ident">a</span>) <span class="op">==</span> <span class="number">0</span>);
<span class="ident">drop</span>(<span class="ident">c</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">try_unwrap</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">3</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">try_unwrap</span>(<span class="ident">x</span>), <span class="prelude-val">Ok</span>(<span class="number">3</span>));
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">4</span>);
<span class="kw">let</span> <span class="ident">_y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">try_unwrap</span>(<span class="ident">x</span>), <span class="prelude-val">Err</span>(<span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">4</span>)));
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">_w</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">x</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">try_unwrap</span>(<span class="ident">x</span>), <span class="prelude-val">Ok</span>(<span class="number">5</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">into_from_raw</span>() {
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="kw">box</span> <span class="string">"hello"</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">x_ptr</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">into_raw</span>(<span class="ident">x</span>);
<span class="ident">drop</span>(<span class="ident">y</span>);
<span class="kw">unsafe</span> {
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x_ptr</span>, <span class="string">"hello"</span>);
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from_raw</span>(<span class="ident">x_ptr</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">x</span>, <span class="string">"hello"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">try_unwrap</span>(<span class="ident">x</span>).<span class="ident">map</span>(<span class="op">|</span><span class="ident">x</span><span class="op">|</span> <span class="kw-2">*</span><span class="ident">x</span>), <span class="prelude-val">Ok</span>(<span class="string">"hello"</span>));
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_into_from_raw_unsized</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::<span class="ident">Display</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">string</span>::<span class="ident">ToString</span>;
<span class="kw">let</span> <span class="ident">rc</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="string">"foo"</span>);
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">into_raw</span>(<span class="ident">rc</span>.<span class="ident">clone</span>());
<span class="kw">let</span> <span class="ident">rc2</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">Rc</span>::<span class="ident">from_raw</span>(<span class="ident">ptr</span>) };
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">ptr</span> }, <span class="string">"foo"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">rc</span>, <span class="ident">rc2</span>);
<span class="kw">let</span> <span class="ident">rc</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Display</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">123</span>);
<span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">into_raw</span>(<span class="ident">rc</span>.<span class="ident">clone</span>());
<span class="kw">let</span> <span class="ident">rc2</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">Rc</span>::<span class="ident">from_raw</span>(<span class="ident">ptr</span>) };
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">ptr</span> }.<span class="ident">to_string</span>(), <span class="string">"123"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">rc2</span>.<span class="ident">to_string</span>(), <span class="string">"123"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">get_mut</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">3</span>);
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">get_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>).<span class="ident">unwrap</span>() <span class="op">=</span> <span class="number">4</span>;
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">x</span>, <span class="number">4</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">x</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">get_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>).<span class="ident">is_none</span>());
<span class="ident">drop</span>(<span class="ident">y</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">get_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>).<span class="ident">is_some</span>());
<span class="kw">let</span> <span class="ident">_w</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">x</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">get_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">x</span>).<span class="ident">is_none</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_cowrc_clone_make_unique</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cow0</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">75</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cow1</span> <span class="op">=</span> <span class="ident">cow0</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cow2</span> <span class="op">=</span> <span class="ident">cow1</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow0</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow1</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow2</span>));
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow0</span>) <span class="op">+=</span> <span class="number">1</span>;
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow1</span>) <span class="op">+=</span> <span class="number">2</span>;
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow2</span>) <span class="op">+=</span> <span class="number">3</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">76</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">77</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">78</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
<span class="comment">// none should point to the same backing memory</span>
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow0</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="ident">cow1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow0</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow1</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_cowrc_clone_unique2</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cow0</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">75</span>);
<span class="kw">let</span> <span class="ident">cow1</span> <span class="op">=</span> <span class="ident">cow0</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">cow2</span> <span class="op">=</span> <span class="ident">cow1</span>.<span class="ident">clone</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow0</span>) <span class="op">+=</span> <span class="number">1</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">76</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
<span class="comment">// cow1 and cow2 should share the same contents</span>
<span class="comment">// cow0 should have a unique reference</span>
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow0</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="ident">cow1</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow0</span> <span class="op">!=</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">cow1</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_cowrc_clone_weak</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cow0</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">75</span>);
<span class="kw">let</span> <span class="ident">cow1_weak</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">75</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow1_weak</span>.<span class="ident">upgrade</span>().<span class="ident">unwrap</span>());
<span class="kw-2">*</span><span class="ident">Rc</span>::<span class="ident">make_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cow0</span>) <span class="op">+=</span> <span class="number">1</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">76</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">cow0</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">cow1_weak</span>.<span class="ident">upgrade</span>().<span class="ident">is_none</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_show</span>() {
<span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">75</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">format</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">foo</span>), <span class="string">"75"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_unsized</span>() {
<span class="kw">let</span> <span class="ident">foo</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">i32</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">foo</span>, <span class="ident">foo</span>.<span class="ident">clone</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_owned</span>() {
<span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="number">123</span>;
<span class="kw">let</span> <span class="ident">foo_rc</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">foo</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="number">123</span> <span class="op">==</span> <span class="kw-2">*</span><span class="ident">foo_rc</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_new_weak</span>() {
<span class="kw">let</span> <span class="ident">foo</span>: <span class="ident">Weak</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span> <span class="op">=</span> <span class="ident">Weak</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">foo</span>.<span class="ident">upgrade</span>().<span class="ident">is_none</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_ptr_eq</span>() {
<span class="kw">let</span> <span class="ident">five</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="kw">let</span> <span class="ident">same_five</span> <span class="op">=</span> <span class="ident">five</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">other_five</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="number">5</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">Rc</span>::<span class="ident">ptr_eq</span>(<span class="kw-2">&</span><span class="ident">five</span>, <span class="kw-2">&</span><span class="ident">same_five</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">Rc</span>::<span class="ident">ptr_eq</span>(<span class="kw-2">&</span><span class="ident">five</span>, <span class="kw-2">&</span><span class="ident">other_five</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_str</span>() {
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="string">"foo"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], <span class="string">"foo"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_copy_from_slice</span>() {
<span class="kw">let</span> <span class="ident">s</span>: <span class="kw-2">&</span>[<span class="ident">u32</span>] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">s</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_clone_from_slice</span>() {
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>, <span class="ident">Eq</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">struct</span> <span class="ident">X</span>(<span class="ident">u32</span>);
<span class="kw">let</span> <span class="ident">s</span>: <span class="kw-2">&</span>[<span class="ident">X</span>] <span class="op">=</span> <span class="kw-2">&</span>[<span class="ident">X</span>(<span class="number">1</span>), <span class="ident">X</span>(<span class="number">2</span>), <span class="ident">X</span>(<span class="number">3</span>)];
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">X</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">s</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], <span class="ident">s</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="attribute">#[<span class="ident">should_panic</span>]</span>
<span class="kw">fn</span> <span class="ident">test_clone_from_slice_panic</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">string</span>::{<span class="ident">String</span>, <span class="ident">ToString</span>};
<span class="kw">struct</span> <span class="ident">Fail</span>(<span class="ident">u32</span>, <span class="ident">String</span>);
<span class="kw">impl</span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Fail</span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Fail</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="number">0</span> <span class="op">==</span> <span class="number">2</span> {
<span class="macro">panic</span><span class="macro">!</span>();
}
<span class="ident">Fail</span>(<span class="self">self</span>.<span class="number">0</span>, <span class="self">self</span>.<span class="number">1</span>.<span class="ident">clone</span>())
}
}
<span class="kw">let</span> <span class="ident">s</span>: <span class="kw-2">&</span>[<span class="ident">Fail</span>] <span class="op">=</span> <span class="kw-2">&</span>[
<span class="ident">Fail</span>(<span class="number">0</span>, <span class="string">"foo"</span>.<span class="ident">to_string</span>()),
<span class="ident">Fail</span>(<span class="number">1</span>, <span class="string">"bar"</span>.<span class="ident">to_string</span>()),
<span class="ident">Fail</span>(<span class="number">2</span>, <span class="string">"baz"</span>.<span class="ident">to_string</span>()),
];
<span class="comment">// Should panic, but not cause memory corruption</span>
<span class="kw">let</span> <span class="ident">_r</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">Fail</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">s</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_box</span>() {
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="kw">box</span> <span class="number">123</span>;
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">b</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">r</span>, <span class="number">123</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_box_str</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">string</span>::<span class="ident">String</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">from</span>(<span class="string">"foo"</span>).<span class="ident">into_boxed_str</span>();
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">str</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">s</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], <span class="string">"foo"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_box_slice</span>() {
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>].<span class="ident">into_boxed_slice</span>();
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">s</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_box_trait</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::<span class="ident">Display</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">string</span>::<span class="ident">ToString</span>;
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">Display</span><span class="op">></span> <span class="op">=</span> <span class="kw">box</span> <span class="number">123</span>;
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Display</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">b</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">r</span>.<span class="ident">to_string</span>(), <span class="string">"123"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_box_trait_zero_sized</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::<span class="ident">Debug</span>;
<span class="kw">let</span> <span class="ident">b</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">Debug</span><span class="op">></span> <span class="op">=</span> <span class="kw">box</span> ();
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Debug</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">b</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="macro">format</span><span class="macro">!</span>(<span class="string">"{:?}"</span>, <span class="ident">r</span>), <span class="string">"()"</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_from_vec</span>() {
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="ident">r</span>: <span class="ident">Rc</span><span class="op"><</span>[<span class="ident">u32</span>]<span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">from</span>(<span class="ident">v</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">r</span>[..], [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_downcast</span>() {
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">any</span>::<span class="ident">Any</span>;
<span class="kw">let</span> <span class="ident">r1</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Any</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">i32</span>::<span class="ident">max_value</span>());
<span class="kw">let</span> <span class="ident">r2</span>: <span class="ident">Rc</span><span class="op"><</span><span class="ident">Any</span><span class="op">></span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="string">"abc"</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">r1</span>.<span class="ident">clone</span>().<span class="ident">downcast</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>().<span class="ident">is_err</span>());
<span class="kw">let</span> <span class="ident">r1i32</span> <span class="op">=</span> <span class="ident">r1</span>.<span class="ident">downcast</span>::<span class="op"><</span><span class="ident">i32</span><span class="op">></span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">r1i32</span>.<span class="ident">is_ok</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">r1i32</span>.<span class="ident">unwrap</span>(), <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">i32</span>::<span class="ident">max_value</span>()));
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">r2</span>.<span class="ident">clone</span>().<span class="ident">downcast</span>::<span class="op"><</span><span class="ident">i32</span><span class="op">></span>().<span class="ident">is_err</span>());
<span class="kw">let</span> <span class="ident">r2str</span> <span class="op">=</span> <span class="ident">r2</span>.<span class="ident">downcast</span>::<span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'static</span> <span class="ident">str</span><span class="op">></span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">r2str</span>.<span class="ident">is_ok</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">r2str</span>.<span class="ident">unwrap</span>(), <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="string">"abc"</span>));
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">borrow</span>::<span class="ident">Borrow</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">borrow</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">since</span> <span class="op">=</span> <span class="string">"1.5.0"</span>, <span class="ident">feature</span> <span class="op">=</span> <span class="string">"smart_ptr_as_ref"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">AsRef</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Rc</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">as_ref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>
}
}
</pre>
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