| <!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/tokio-stream-0.1.14/src/once.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>once.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="../../tokio_stream/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="../../tokio_stream/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 crate</span>::{Iter, Stream}; |
| |
| <span class="kw">use </span>core::option; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>core::task::{Context, Poll}; |
| |
| <span class="doccomment">/// Stream for the [`once`](fn@once) 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>Once<T> { |
| iter: Iter<option::IntoIter<T>>, |
| } |
| |
| <span class="kw">impl</span><I> Unpin <span class="kw">for </span>Once<I> {} |
| |
| <span class="doccomment">/// Creates a stream that emits an element exactly once. |
| /// |
| /// The returned stream is immediately ready and emits the provided value once. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_stream::{self as stream, StreamExt}; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// // one is the loneliest number |
| /// let mut one = stream::once(1); |
| /// |
| /// assert_eq!(Some(1), one.next().await); |
| /// |
| /// // just one, that's all we get |
| /// assert_eq!(None, one.next().await); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>once<T>(value: T) -> Once<T> { |
| Once { |
| iter: <span class="kw">crate</span>::iter(<span class="prelude-val">Some</span>(value).into_iter()), |
| } |
| } |
| |
| <span class="kw">impl</span><T> Stream <span class="kw">for </span>Once<T> { |
| <span class="kw">type </span>Item = T; |
| |
| <span class="kw">fn </span>poll_next(<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="prelude-ty">Option</span><T>> { |
| Pin::new(<span class="kw-2">&mut </span><span class="self">self</span>.iter).poll_next(cx) |
| } |
| |
| <span class="kw">fn </span>size_hint(<span class="kw-2">&</span><span class="self">self</span>) -> (usize, <span class="prelude-ty">Option</span><usize>) { |
| <span class="self">self</span>.iter.size_hint() |
| } |
| } |
| </code></pre></div> |
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