| <!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/try_maybe_done.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>try_maybe_done.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="doccomment">//! Definition of the TryMaybeDone combinator |
| |
| </span><span class="kw">use </span><span class="kw">super</span>::assert_future; |
| <span class="kw">use </span>core::mem; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::future::{FusedFuture, Future, TryFuture}; |
| <span class="kw">use </span>futures_core::ready; |
| <span class="kw">use </span>futures_core::task::{Context, Poll}; |
| |
| <span class="doccomment">/// A future that may have completed with an error. |
| /// |
| /// This is created by the [`try_maybe_done()`] function. |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub enum </span>TryMaybeDone<Fut: TryFuture> { |
| <span class="doccomment">/// A not-yet-completed future |
| </span>Future(<span class="comment">/* #[pin] */ </span>Fut), |
| <span class="doccomment">/// The output of the completed future |
| </span>Done(Fut::Ok), |
| <span class="doccomment">/// The empty variant after the result of a [`TryMaybeDone`] has been |
| /// taken using the [`take_output`](TryMaybeDone::take_output) method, |
| /// or if the future returned an error. |
| </span>Gone, |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture + Unpin> Unpin <span class="kw">for </span>TryMaybeDone<Fut> {} |
| |
| <span class="doccomment">/// Wraps a future into a `TryMaybeDone` |
| </span><span class="kw">pub fn </span>try_maybe_done<Fut: TryFuture>(future: Fut) -> TryMaybeDone<Fut> { |
| assert_future::<<span class="prelude-ty">Result</span><(), Fut::Error>, <span class="kw">_</span>>(TryMaybeDone::Future(future)) |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture> TryMaybeDone<Fut> { |
| <span class="doccomment">/// Returns an [`Option`] containing a mutable reference to the output of the future. |
| /// The output of this method will be [`Some`] if and only if the inner |
| /// future has completed successfully and [`take_output`](TryMaybeDone::take_output) |
| /// has not yet been called. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>output_mut(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) -> <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>Fut::Ok> { |
| <span class="kw">unsafe </span>{ |
| <span class="kw">match </span><span class="self">self</span>.get_unchecked_mut() { |
| TryMaybeDone::Done(res) => <span class="prelude-val">Some</span>(res), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Attempt to take the output of a `TryMaybeDone` without driving it |
| /// towards completion. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>take_output(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) -> <span class="prelude-ty">Option</span><Fut::Ok> { |
| <span class="kw">match </span><span class="kw-2">&*</span><span class="self">self </span>{ |
| <span class="self">Self</span>::Done(<span class="kw">_</span>) => {} |
| <span class="self">Self</span>::Future(<span class="kw">_</span>) | <span class="self">Self</span>::Gone => <span class="kw">return </span><span class="prelude-val">None</span>, |
| } |
| <span class="kw">unsafe </span>{ |
| <span class="kw">match </span>mem::replace(<span class="self">self</span>.get_unchecked_mut(), <span class="self">Self</span>::Gone) { |
| TryMaybeDone::Done(output) => <span class="prelude-val">Some</span>(output), |
| <span class="kw">_ </span>=> <span class="macro">unreachable!</span>(), |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture> FusedFuture <span class="kw">for </span>TryMaybeDone<Fut> { |
| <span class="kw">fn </span>is_terminated(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="kw">match </span><span class="self">self </span>{ |
| <span class="self">Self</span>::Future(<span class="kw">_</span>) => <span class="bool-val">false</span>, |
| <span class="self">Self</span>::Done(<span class="kw">_</span>) | <span class="self">Self</span>::Gone => <span class="bool-val">true</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture> Future <span class="kw">for </span>TryMaybeDone<Fut> { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Result</span><(), Fut::Error>; |
| |
| <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<<span class="self">Self</span>::Output> { |
| <span class="kw">unsafe </span>{ |
| <span class="kw">match </span><span class="self">self</span>.as_mut().get_unchecked_mut() { |
| TryMaybeDone::Future(f) => <span class="kw">match </span><span class="macro">ready!</span>(Pin::new_unchecked(f).try_poll(cx)) { |
| <span class="prelude-val">Ok</span>(res) => <span class="self">self</span>.set(<span class="self">Self</span>::Done(res)), |
| <span class="prelude-val">Err</span>(e) => { |
| <span class="self">self</span>.set(<span class="self">Self</span>::Gone); |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(e)); |
| } |
| }, |
| TryMaybeDone::Done(<span class="kw">_</span>) => {} |
| TryMaybeDone::Gone => <span class="macro">panic!</span>(<span class="string">"TryMaybeDone polled after value taken"</span>), |
| } |
| } |
| Poll::Ready(<span class="prelude-val">Ok</span>(())) |
| } |
| } |
| </code></pre></div> |
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