| <!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/select_ok.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>select_ok.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><span class="kw">super</span>::assert_future; |
| <span class="kw">use </span><span class="kw">crate</span>::future::TryFutureExt; |
| <span class="kw">use </span>alloc::vec::Vec; |
| <span class="kw">use </span>core::iter::FromIterator; |
| <span class="kw">use </span>core::mem; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::future::{Future, TryFuture}; |
| <span class="kw">use </span>futures_core::task::{Context, Poll}; |
| |
| <span class="doccomment">/// Future for the [`select_ok`] function. |
| </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>SelectOk<Fut> { |
| inner: Vec<Fut>, |
| } |
| |
| <span class="kw">impl</span><Fut: Unpin> Unpin <span class="kw">for </span>SelectOk<Fut> {} |
| |
| <span class="doccomment">/// Creates a new future which will select the first successful future over a list of futures. |
| /// |
| /// The returned future will wait for any future within `iter` to be ready and Ok. Unlike |
| /// `select_all`, this will only return the first successful completion, or the last |
| /// failure. This is useful in contexts where any success is desired and failures |
| /// are ignored, unless all the futures fail. |
| /// |
| /// This function is only available when the `std` or `alloc` feature of this |
| /// library is activated, and it is activated by default. |
| /// |
| /// # Panics |
| /// |
| /// This function will panic if the iterator specified contains no items. |
| </span><span class="kw">pub fn </span>select_ok<I>(iter: I) -> SelectOk<I::Item> |
| <span class="kw">where |
| </span>I: IntoIterator, |
| I::Item: TryFuture + Unpin, |
| { |
| <span class="kw">let </span>ret = SelectOk { inner: iter.into_iter().collect() }; |
| <span class="macro">assert!</span>(!ret.inner.is_empty(), <span class="string">"iterator provided to select_ok was empty"</span>); |
| assert_future::< |
| <span class="prelude-ty">Result</span><(<I::Item <span class="kw">as </span>TryFuture>::Ok, Vec<I::Item>), <I::Item <span class="kw">as </span>TryFuture>::Error>, |
| <span class="kw">_</span>, |
| >(ret) |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture + Unpin> Future <span class="kw">for </span>SelectOk<Fut> { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Result</span><(Fut::Ok, Vec<Fut>), 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="comment">// loop until we've either exhausted all errors, a success was hit, or nothing is ready |
| </span><span class="kw">loop </span>{ |
| <span class="kw">let </span>item = |
| <span class="self">self</span>.inner.iter_mut().enumerate().find_map(|(i, f)| <span class="kw">match </span>f.try_poll_unpin(cx) { |
| Poll::Pending => <span class="prelude-val">None</span>, |
| Poll::Ready(e) => <span class="prelude-val">Some</span>((i, e)), |
| }); |
| <span class="kw">match </span>item { |
| <span class="prelude-val">Some</span>((idx, res)) => { |
| <span class="comment">// always remove Ok or Err, if it's not the last Err continue looping |
| </span>drop(<span class="self">self</span>.inner.remove(idx)); |
| <span class="kw">match </span>res { |
| <span class="prelude-val">Ok</span>(e) => { |
| <span class="kw">let </span>rest = mem::take(<span class="kw-2">&mut </span><span class="self">self</span>.inner); |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Ok</span>((e, rest))); |
| } |
| <span class="prelude-val">Err</span>(e) => { |
| <span class="kw">if </span><span class="self">self</span>.inner.is_empty() { |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Err</span>(e)); |
| } |
| } |
| } |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="comment">// based on the filter above, nothing is ready, return |
| </span><span class="kw">return </span>Poll::Pending; |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><Fut: TryFuture + Unpin> FromIterator<Fut> <span class="kw">for </span>SelectOk<Fut> { |
| <span class="kw">fn </span>from_iter<T: IntoIterator<Item = Fut>>(iter: T) -> <span class="self">Self </span>{ |
| select_ok(iter) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="futures_util" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
