| <!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 of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.28/src/future/future/fuse.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>fuse.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../futures_util/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../futures_util/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::future::{FusedFuture, Future}; |
| <span class="kw">use </span>futures_core::task::{Context, Poll}; |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`fuse`](super::FutureExt::fuse) method. |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="kw">pub struct </span>Fuse<Fut> { |
| <span class="attribute">#[pin] |
| </span>inner: <span class="prelude-ty">Option</span><Fut>, |
| } |
| } |
| |
| <span class="kw">impl</span><Fut> Fuse<Fut> { |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>new(f: Fut) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ inner: <span class="prelude-val">Some</span>(f) } |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: Future> Fuse<Fut> { |
| <span class="doccomment">/// Creates a new `Fuse`-wrapped future which is already terminated. |
| /// |
| /// This can be useful in combination with looping and the `select!` |
| /// macro, which bypasses terminated futures. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::channel::mpsc; |
| /// use futures::future::{Fuse, FusedFuture, FutureExt}; |
| /// use futures::select; |
| /// use futures::stream::StreamExt; |
| /// use futures::pin_mut; |
| /// |
| /// let (sender, mut stream) = mpsc::unbounded(); |
| /// |
| /// // Send a few messages into the stream |
| /// sender.unbounded_send(()).unwrap(); |
| /// sender.unbounded_send(()).unwrap(); |
| /// drop(sender); |
| /// |
| /// // Use `Fuse::terminated()` to create an already-terminated future |
| /// // which may be instantiated later. |
| /// let foo_printer = Fuse::terminated(); |
| /// pin_mut!(foo_printer); |
| /// |
| /// loop { |
| /// select! { |
| /// _ = foo_printer => {}, |
| /// () = stream.select_next_some() => { |
| /// if !foo_printer.is_terminated() { |
| /// println!("Foo is already being printed!"); |
| /// } else { |
| /// foo_printer.set(async { |
| /// // do some other async operations |
| /// println!("Printing foo from `foo_printer` future"); |
| /// }.fuse()); |
| /// } |
| /// }, |
| /// complete => break, // `foo_printer` is terminated and the stream is done |
| /// } |
| /// } |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>terminated() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ inner: <span class="prelude-val">None </span>} |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: Future> FusedFuture <span class="kw">for </span>Fuse<Fut> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.inner.is_none() |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: Future> Future <span class="kw">for </span>Fuse<Fut> { |
| <span class="kw">type </span>Output = Fut::Output; |
| |
| <span class="kw">fn </span>poll(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<Fut::Output> { |
| <span class="kw">match </span><span class="self">self</span>.as_mut().project().inner.as_pin_mut() { |
| <span class="prelude-val">Some</span>(fut) => fut.poll(cx).map(|output| { |
| <span class="self">self</span>.project().inner.set(<span class="prelude-val">None</span>); |
| output |
| }), |
| <span class="prelude-val">None </span>=> Poll::Pending, |
| } |
| } |
| } |
| </code></pre></div> |
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