| <!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/stream/select.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>select.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_stream; |
| <span class="kw">use </span><span class="kw">crate</span>::stream::{select_with_strategy, PollNext, SelectWithStrategy}; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>futures_core::stream::{FusedStream, Stream}; |
| <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">/// Stream for the [`select()`] function. |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"streams do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>Select<St1, St2> { |
| <span class="attribute">#[pin] |
| </span>inner: SelectWithStrategy<St1, St2, <span class="kw">fn</span>(<span class="kw-2">&mut </span>PollNext)-> PollNext, PollNext>, |
| } |
| } |
| |
| <span class="doccomment">/// This function will attempt to pull items from both streams. Each |
| /// stream will be polled in a round-robin fashion, and whenever a stream is |
| /// ready to yield an item that item is yielded. |
| /// |
| /// After one of the two input streams completes, the remaining one will be |
| /// polled exclusively. The returned stream completes when both input |
| /// streams have completed. |
| /// |
| /// Note that this function consumes both streams and returns a wrapped |
| /// version of them. |
| /// |
| /// ## Examples |
| /// |
| /// ```rust |
| /// # futures::executor::block_on(async { |
| /// use futures::stream::{ repeat, select, StreamExt }; |
| /// |
| /// let left = repeat(1); |
| /// let right = repeat(2); |
| /// |
| /// let mut out = select(left, right); |
| /// |
| /// for _ in 0..100 { |
| /// // We should be alternating. |
| /// assert_eq!(1, out.select_next_some().await); |
| /// assert_eq!(2, out.select_next_some().await); |
| /// } |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>select<St1, St2>(stream1: St1, stream2: St2) -> Select<St1, St2> |
| <span class="kw">where |
| </span>St1: Stream, |
| St2: Stream<Item = St1::Item>, |
| { |
| <span class="kw">fn </span>round_robin(last: <span class="kw-2">&mut </span>PollNext) -> PollNext { |
| last.toggle() |
| } |
| |
| assert_stream::<St1::Item, <span class="kw">_</span>>(Select { |
| inner: select_with_strategy(stream1, stream2, round_robin), |
| }) |
| } |
| |
| <span class="kw">impl</span><St1, St2> Select<St1, St2> { |
| <span class="doccomment">/// Acquires a reference to the underlying streams that this combinator is |
| /// pulling from. |
| </span><span class="kw">pub fn </span>get_ref(<span class="kw-2">&</span><span class="self">self</span>) -> (<span class="kw-2">&</span>St1, <span class="kw-2">&</span>St2) { |
| <span class="self">self</span>.inner.get_ref() |
| } |
| |
| <span class="doccomment">/// Acquires a mutable reference to the underlying streams that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| </span><span class="kw">pub fn </span>get_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> (<span class="kw-2">&mut </span>St1, <span class="kw-2">&mut </span>St2) { |
| <span class="self">self</span>.inner.get_mut() |
| } |
| |
| <span class="doccomment">/// Acquires a pinned mutable reference to the underlying streams that this |
| /// combinator is pulling from. |
| /// |
| /// Note that care must be taken to avoid tampering with the state of the |
| /// stream which may otherwise confuse this combinator. |
| </span><span class="kw">pub fn </span>get_pin_mut(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) -> (Pin<<span class="kw-2">&mut </span>St1>, Pin<<span class="kw-2">&mut </span>St2>) { |
| <span class="kw">let </span>this = <span class="self">self</span>.project(); |
| this.inner.get_pin_mut() |
| } |
| |
| <span class="doccomment">/// Consumes this combinator, returning the underlying streams. |
| /// |
| /// Note that this may discard intermediate state of this combinator, so |
| /// care should be taken to avoid losing resources when this is called. |
| </span><span class="kw">pub fn </span>into_inner(<span class="self">self</span>) -> (St1, St2) { |
| <span class="self">self</span>.inner.into_inner() |
| } |
| } |
| |
| <span class="kw">impl</span><St1, St2> FusedStream <span class="kw">for </span>Select<St1, St2> |
| <span class="kw">where |
| </span>St1: Stream, |
| St2: Stream<Item = St1::Item>, |
| { |
| <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_terminated() |
| } |
| } |
| |
| <span class="kw">impl</span><St1, St2> Stream <span class="kw">for </span>Select<St1, St2> |
| <span class="kw">where |
| </span>St1: Stream, |
| St2: Stream<Item = St1::Item>, |
| { |
| <span class="kw">type </span>Item = St1::Item; |
| |
| <span class="kw">fn </span>poll_next(<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="prelude-ty">Option</span><St1::Item>> { |
| <span class="kw">let </span>this = <span class="self">self</span>.project(); |
| this.inner.poll_next(cx) |
| } |
| } |
| </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> |